News from Rohde & Schwarz

Multimedia Rohde & Schwarz right there from the start

Radio test and measurement Innovation in mobile phone testing

ATC radiocommunications Now with RCMS and 8.33-kHz channel spacing

152 Number 152 1996/III Volume 36

Digital broadcasting and multimedia communication are the topics of our final article (page 57) which breaches the gap between the world of analog sound and TV broadcasting and that of digital audio and video broadcasting with its interactive communication facilities. The photo on the cover is to give an impression of this multimedia world. For more information about digital TV see our articles on pages 17 and 20.

Articles

Michael Vohrer Digital Radio Tester CTS55 All-in-one service tester for GSM, PCN and PCS mobile telephones...... 4 Josef Wolf Spectrum Analyzer FSEM/FSEK Fast spectrum analysis now through to 40 GHz ...... 7 Jon Pedersen Calibration System TS9099 Automatic test equipment calibration to ISO 9000 ...... 10 Thomas Kneidel System Processor MERLIN GR2000 Powerful processor stands toughest conditions ...... 12 Hans-Günther Klarl; Series 200 and 400U radio equipment Martin Kessler Innovations in ATC radiocommunications: RCMS and 8.33-kHz channel spacing...14 Christoph Balz; Ernst Polz; TV Test Receiver Family EFA Walter Fischer Top fit for digital television...... 17 Michael Fischbacher; MPEG2 Generator DVG and MPEG2 Measurement Decoder DVMD Harald Weigold Test equipment for digital TV in line with MPEG2 ...... 20 Rainer Steen; 100/200-W Solid-State DAB Transmitter NL5010/5020 Johannes Steffens Terrestrial broadcasting of digital audio in L band ...... 24 Walter Deschler; TV Transmitter Test System TS6140 Gerhard Strauss Guarantee of high signal quality in TV transmitter networks ...... 27 Franz Demmel; VHF-UHF Direction Finder DDF190 Raimund Wille Digital direction finding from 20 to 3000 MHz to ITU guidelines ...... 30

Application notes

Wilhelm Kraemer EMC measurements up to 40 GHz with Microwave Signal Generator SMP ...... 33 Tilman Betz Measurements on hearing aids with Audio Analyzers UPD and UPL...... 36 Thomas Maucksch Quality testing of mobile phones using multitone audio analysis of Digital Radiocommunication Tester CMD...... 38 Joachim Stegmaier Tailor-made applications in industrial automation with factory user port for Controller PSM ...... 40 Günter Wicker; Fast adaptive data transmission on shortwave Gerhard Greubel at up to 5400 bit/s via HF Modem GM2100 ...... 42

Refresher topic

Peter Hatzold Digital modulation and mobile radio (III)...... 44

2 News from Rohde & Schwarz Number 152 (1996/III) Software

Dr. Hans Waibel; PropWiz – Windows program for shortwave radio link Peter Maurer prediction ...... 46

Panorama

Werner Mittermaier Digital Radiocommunication Tester CMD55 with new measurement functions ...... 48 Andreas Schneider ACCESSNET® – a solution for communications in Russia...... 49 Klaus Wunderlich; Rohde & Schwarz test equipment in EMC test center of Peter Busch safety standards authority of Hesse ...... 51 Jacques Stellamans SNCB uses R&S test system for planning and quality assurance in Belgian railway communications ...... 52

Regular features

Reference: EMC system solutions ...... 29 Marcus Gloger; Test hint: Peter Riedel Optimizing wireless local loop systems ...... 35 Klaus Danzeisen Patent: Frequency-selective measurement and display of frequency-dependent test parameters...... 47 Information in print ...... 53

Newsgrams ...... 54

In memoriam Dr. Rohde ...... 55

Press comments ...... 56 Paul Dambacher Final article: Digital broadcasting and multimedia communication...... 57

The future of sound broadcasting is digital – and Rohde & Schwarz is the perfect partner. The most recent member in our family of DAB transmitters is 100/200-W Solid-State Transmitter NL5010/5020 for the L band (page 24).

Imprint

Published by ROHDE & SCHWARZ GmbH & Co. KG Mühldorfstraße 15 D - 81671 Munich Telephone (0 89) 41 29-0 · international *(4989) 41 29-0 · Telex 523703 (rs d) · Editors: H. Wegener and G. Sönnichsen (German); G. Koranyi, I. Davidson, C. B. Newberry (English) · Photos: S. Huber · Circulation 100 000 three times a year · ISSN 0028-9108 · Supply free of charge · State company or position · Printed in the Federal Republic of Germany by peschke druck, Munich · Reproduction of extracts permitted if source is stated and copy sent to R & S Munich

News from Rohde & Schwarz Number 152 (1996/III) 3 Articles

Digital Radio Tester CTS55 an optimum combination of the GSM/ DCS features of Go/NoGo Testers CTD [1] and the in-depth testing of Digital All-in-one service tester for GSM, Radiocommunication Tester CMD [2; 3] for joint coverage of all aspects of PCN and PCS mobile telephones servicing from simple function tests through to repairs. Its brilliant, high- Digital Radio Tester CTS55 from Rohde & Schwarz is a cost-effective, compact resolution colour display makes using tester for all servicing, maintenance and repair work on GSM, PCN and PCS CTS55 a joy and allows it to show off mobile radiotelephones in a single unit. It therefore bridges the gap between pure its strong points, in particular the result go/nogo tests and sophisticated GSM measurement technology. graphics.

FIG 1 Digital Radio Tester CTS55 provides fast FIG 2 CTS55 autotest automatically checks CTS55’s quick function test can be function testing combined with in-depth mobile all mobile phone characteristics on various RF called at the press of a button and phone tests to GSM, PCN and PCS. channels and displays result as go/nogo or nu- Photo 42 434 merically with out-of-tolerance warnings. produces all the important features of a mobile telephone on different RF channels. As well as a go or nogo

Digital Radio Tester CTS55 (FIG 1) is a synthesis of fast function testing and classic measurement technology for GSM 900, DCS 1800 (PCN) and DCS 1900 (PCS) mobile radio systems. It is

4 News from Rohde & Schwarz Number 152 (1996/III) Articles

display for the particular parameter uation. If required, a test report can be and an overall evaluation, test results output on a printer to show whether can also be shown in very simple nu- repairs are necessary or only as merical form with out-of-range displays backup documentation. When the too (FIG 2). A digital signal processor classic manual mode is used, all allows you to determine power ramp- measurements can be called up with a ing, phase and frequency error and continuous result display. This makes bit error rate in a form like that used alignments and troubleshooting easy if by Digital Radiocommunication Tester repairs have to be made. In particular, CMD. Not only can these functions be the graphic displays showing phase er- called during automatic test sequences, FIG 3 In manual mode CTS55 simultaneously ror, frequency error (FIG 4) and power in conjunction with other test facilities indicates all relevant test values and parameters on ramp (FIG 5) give an exhaustive de- they are also available in the classic its display. scription of the transmitter and make it manual mode. This second mode of easy to determine the causes of faults. operation enables CTS55 to fulfil all the The simultaneous display of the various requirements of a high-flexibility repair bit error rates and frame error rates tester. In addition to the wide range of with a user-selectable measurement digital result displays in a highly prac- interval gives you a relatively deep tical format (FIG 3), graphics for test understanding of receiver character- parameters such as power ramping or istics (FIG 6). phase error can be selected with a single keystroke. For in-depth analysis Operation of Digital Radio Tester there are zoom functions which simplify CTS55 is especially simple, with just six the interpretation of anomalies and so softkeys and easy-to-understand screen make servicing easier. prompts. A sophisticated menu structure navigates almost automatically CTS55 has the following test and through the measurement, and the measurement facilities for fast testing multilingual user interface (English, Ger- and in-depth analysis of mobile FIG 4 Phase/frequency curve and numerical man, French, Italian, Dutch, Spanish) phones: display of current, average and maximum value prevents misinterpretations and incor- provide information about modulation charac- rect operation. Direct access softkeys • synchronization of mobile phones teristics of mobile phone. are used to control the tester. This also with base stations (simulated by includes calling tests and selecting CTS55), parameters; an ASCII keyboard can • registration (location update), also be connected. If an automatic test • incoming and outgoing call setup, sequence is being run, it is possible to • incoming and outgoing call clear- change over to graphic mode to carry down, out additional detailed analysis if an • control and measurement of trans- out-of-tolerance condition is encoun- mitting power, tered for example. • handover (channel change), • measurement of peak power, Digital Radio Tester CTS55 is designed • sensitivity measurement (RxQual, as a mini base station with indepen- RxLev), dent transmit and receive channels and • function test on dialling pad by realtime signalling for the broadcast displaying the called number, control channel (BCCH) and traffic • display of IMSI (international mobile channel (TCH). Several processors subscriber identity) and IMEI (inter- generate and analyze test signals or national mobile equipment identity), are used to return the words spoken • echo test, During the fast function test or go/nogo into the microphone to the mobile tele- • bit error rate and frame error rate test CTS55 measures all the parameters phone receiver with a defined delay. measurements, of the mobile phone on any selectable • phase error measurement, RF channel and clearly displays the Digital Radio Tester CTS55 measures • frequency error measurement, function in the form of individual all parameters that could influence cor- • power ramping measurement. evaluations and of an overall eval- rect phone operation. Besides power

News from Rohde & Schwarz Number 152 (1996/III) 5 Articles

FIG 5 Power ramp with inserted tolerance • test SIM (subscriber identity module) REFERENCES window makes it easy to detect deviations from to put a mobile telephone into ser- [1] Vohrer, M.: GSM Go/NoGo Tester CTD52 – nominal curve. vice – even without a customer card The smallest base station in the world for testing GSM mobile phones. News from (CRT-Z2). Rohde & Schwarz (1995) No. 147, pp 4 – 6 [2] Mittermaier, W.: Module test with Digital Due to its great variety of functions, low Radiocommunication Tester CMD52/55. level it determines phase and frequency weight of less than 8 kg as well as small News from Rohde & Schwarz (1995) No. error and power ramping as well as the dimensions and ease of operation, the 149, pp 36 – 37 various bit error rates and frame error applications of CTS55 range from use [3] Vohrer, M.: Low-cost Service Radiocommuni- cation Testers CMD50/53 for GSM/PCN/ rate. Options and accessories are as sales support for mobile phones to a PCS mobiles. News from Rohde & Schwarz available to increase the ease of oper- repair tester in service departments or (1996) No. 150, pp 54 – 55 ation and test accuracy of CTS55: in production. Last but not least, the ex- ceptional price/performance ratio of Digital Radio Tester CTS55 now makes it the most interesting solution for servicing tasks in the GSM/PCN/PCS mobile phone sector. Michael Vohrer

FIG 6 During receiver test, CTS55 simultaneously indicates relevant bit error rates (RBER II and RBER IIb) and frame error rate (FER) as well as RxQual and RxLev values sent back by mobile phone for monitoring.

Condensed data of Digital Radio Tester CTS55 DUTs GSM, PCN (DCS 1800), PCS (DCS 1900) mobile phones • OCXO reference oscillator for Operating modes manual and fully automatic test sequence with enhanced accuracy of all frequency- printer report related test parameters (CTS-B1), Functions synchronization, registration, call setup, call clear- down, channel change, power change, echo test • small RF-shielded case (CTD-Z10) for Test facilities sensitivity (RxLev, RxQual), power, power DUTs to prevent spurious test results ramping, frequency error, phase error, caused by local GSM, PCN or PCS BER (RBER II, RBER IIb), FER, IMSI, IMEI networks, especially in the case of Reader service card 152/01 bit error rate measurements,

6 News from Rohde & Schwarz Number 152 (1996/III) Articles

Spectrum Analyzer FSEM/FSEK (FIG 1). The FSE family consists of eight models that differ in performance and frequency range (FIG 2). The Fast spectrum analysis upper frequency limit of the FSEM models is 26.5 GHz (overrange up to now through to 40 GHz 27 GHz), that of the FSEK models 40 GHz. The performance of models 20 is that of the high-end of the medium There are new additions to the FSE spectrum analyzer family: in Spectrum Ana- class, whereas models 30 are absolute lyzer FSEM Rohde & Schwarz has now moved into the microwave range through top-class models. to 26.5 GHz and, with FSEK, for the first time through to 40 GHz. New on the world market is a vector signal analyzer option which allows modulation analy- Dense spectrum occupancy places sis of digitally modulated signals at these frequencies. Standards of measurement high demands on the transmitters and speed, precision, dynamic range and spectral purity, set by FSE in the RF range, receivers of a communication system. are of course maintained by the latest members of the family in the microwave Interference of adjacent channels and range. other radio services has to be avoided. Adjacent channels may be impaired in particular by the modulation spectrum and by intermodulation at the transmitter, other radio services by spurious emissions or especially harmonics of the transmitter. For all communication systems these spectral characteristics are subject to very stringent specifications. A suitable spectrum analyzer is therefore required to verify the characteristics in development, production or service. Inadequate characteristics of a measuring instrument, for example too low a dynamic range, can be compensated by external units such as pre- amplifiers and switchable filters but will always involve extra costs (additional hardware and longer test times) and at the same time the risk of erroneous measurements. FIG 1 Spectrum Analyzer FSEM up to 26.5 GHz and Dynamic range FSEK up to 40 GHz Photo 42 573 Dynamic range is one of the key parameters of a spectrum analyzer. Increasing communication traffic and a new members of the FSE spectrum Dynamic range covers different charac- densely occupied frequency spectrum analyzer family [1; 2]: FSEM and FSEK teristics such as sensitivity, overdrive in the lower frequency range are the reasons for resorting to higher and FSEA30 higher frequencies. The transition from FSEA20 voice or data transmission to digital FSEB30 picture transmission requires wider FSEB20 bandwidth per channel and denser FSEM30 spectrum occupancy. For T&M these trends call for higher frequency limits FSEM20 for characteristics that up to now were FSEK30 only necessary for the lower frequency FIG 2 FSEK20 range. Rohde & Schwarz takes these Frequency range 20 Hz 9 kHz 3.5 GHz 26.5 GHz trends fully into account by offering two of eight FSE models 7 GHz 40 GHz

News from Rohde & Schwarz Number 152 (1996/III) 7 Articles

(1-dB compression), intermodulation, sweep speeds – a considerable gain phase noise and display range. Micro- in time and thus a cost reduction in wave analyzers FSEM and FSEK of the production for example. FSE family offer excellent figures for all the above-mentioned parameters. In addition to sensitivity, large-signal behaviour is important for dynamic A precondition for high dynamic range range, ie 1-dB compression, intermod- is high sensitivity to analyze weak sig- ulation-free range or harmonics sup- nals. To achieve high sensitivity, FSEM pression. For all three parameters mi- and FSEK operate with fundamental crowave analyzers FSEM and FSEK FIG 4 Single-sideband phase noise of FSEM mixing up to an input frequency of yield the same excellent characteristics and FSEK at 500-MHz and 26.5-GHz input fre- 26.5 GHz, ie the input mixer uses the as low-frequency analyzers FSEA and quencies fundamental of the first LO to convert FSEB. The 1-dB compression of the RF the input signal to the first IF. Thus the input of +10 dB allows measurement of mixer yields low conversion loss, which very weak signals in the presence of in turn is reflected in the noise figure high signal levels without impairing the (FIG 3). Above 26.5 GHz, FSEK mixes weak signal. The signal path to the IF usual test setups for phase-noise meas- with the fourth harmonic of the LO. filters can be overdriven by 15 dB urement. Most spectrum analyzers use harmonic above reference level. Overdrive indi- mixing at frequencies well below cations warn the user if the input signal Precision 10 GHz (6 to 8 GHz). So harmonics of is too high – also in the case of auto- signals might no longer be detected matic operation from a controller. This As far as precision is concerned, micro- due to the reduced sensitivity of the saves the use of notch filters at the wave analyzers FSEM and FSEK show, analyzer. In this case an external pre- transmit frequency in the measurement like the other members of the family in amplifier and a highpass filter for atten- of nonharmonics, for example, and the RF range, characteristics that have uating the fundamental are required. makes for a simplified test setup. not been matched so far, ie frequency The low noise floor also brings an Together with resolution bandwidth of accuracy, level measurement accuracy advantage in speed: a wider resolution 10 Hz, the third-order intercept point of and reproducibility of results. +15 dBm yields an intermodulation-free range of more than 100 dB. The result Even at large frequency spans, fre- of this is as follows: if several large RF quency accuracy is attained by a signals are present at the antenna con- sweep with the first conversion oscil- nector of a mobile radio base station, lator locked to the internal or external for example, signals with a difference reference at each frequency. At rela- in level of up to 100 dB can still be tively small spans from about 5 MHz measured without requiring notch filters most spectrum analyzers use a free-run- to suppress the high levels. ning YIG oscillator tuned by an analog sawtooth voltage. The nonlinearity of Especially if nonharmonics in adjacent the YIG tuning characteristic has a channels have to be measured, the direct effect on frequency accuracy. phase noise of the internal oscillators Things are quite different with the FSE is a decisive factor for dynamic range. family. Even for the maximum span Too much phase noise suppresses weak of 27 or 40 GHz the tuning oscillator is

FIG 3 Noise display of FSEM over whole signals or spectral components in the crystal-accurate at any frequency – and frequency range measured with bandwidth of adjacent channel, but the spectrum an- at that even for the minimum sweep 1 MHz (top) and in range important for radio alyzers of the FSE family are exemplary time of 5 ms. Frequency lines indicated transmission to 2.5 GHz in this respect too (FIG 4). It is note- with a marker can be displayed direct worthy that the low phase noise in with high resolution and without the vicinity of the carrier drops to intermediate steps – in the split-screen 140 dBc per 1-Hz test bandwidth display simultaneously in a second filter can be used to attain the same dis- at 10 MHz. Even the phase noise of measurement window. played noise floor as with less sensitive oscillators for transmitters or receivers spectrum analyzers. The double band- can be measured with sufficient dy- Like with FSEA and FSEB level meas- width results in a displayed noise floor namic range – a major advantage in urement accuracy is also very high on that is 3 dB higher but allows fourfold speed and handling compared to the the agenda for microwave analyzers

8 News from Rohde & Schwarz Number 152 (1996/III) Articles

(FIG 5). For these analyzers too, Rohde Speed Microwave analyzers FSEM and FSEK & Schwarz gives the guarantee that a can of course be extended to applica- maximum total level error will not be Time is one of the most important cost tion-specific solutions with the same op- exceeded – a claim unique amongst factors, in development where products tions as the RF analyzers. Vector Signal spectrum analyzers. The total error is as have to be launched fast, or in produc- Analyzer Option FSE-B7 [2] deserves low as 1 dB (up to 1 GHz) and 3.5 dB tion where products have to be manu- special mention since for the first time (at 40 GHz) in the whole temperature factured at high throughput and thus modulation analysis of digitally or ana- range. This is made possible for the first cost-effectively. Here too FSEM and log-modulated signals is now possible time by very stringent production toler- FSEK set standards in many ways and also in the microwave range in a single ances and internal calibration routines help the user reduce costs by saving unit. for absolute gain, the resolution filters time and thus become more competi- Josef Wolf (bandwidth and gain) and for the log tive: the fast synthesizer allows a mini- amplifier characteristic together with mum sweep time of 5 ms up to 7 GHz correction data stored on each module and 150 ms over the whole frequency for the frequency response of for exam- range at full level measurement accu- ple the attenuator, the YIG preselector racy. With 25 pictures per second, pro- and the front-end. The guaranteed level cedures can be analyzed practically in measurement accuracy often spares the realtime. Manual alignments can be user an elaborate correction, eg with performed with an “analog feeling”. an additional power meter, provides The 20-MHz A/D converter also measurement reliability and tolerances allows display of short signals with high resolution (100 ns/div) thanks to the maximum bandwidth of 10 MHz. The

high computing power (586 PC with REFERENCES 133-MHz clock frequency, transputer [1] Wolf, J.: Spectrum Analyzer FSEA/FSEB – network and DSPs) yields very fast New dimensions in spectral analysis. News response times and data outputs on from Rohde & Schwarz (1995) No. 148, the IEC/IEEE bus even in the case of pp 4–8 complex functions such as phase noise [2] Wolf, J.: Spectrum Analyzer FSE with Option FSE-B7 – Vector signal analysis – indis- measurement, power or adjacent- pensable in digital mobile radio. News from power measurement and optionally for Rohde & Schwarz (1996) No. 150, several channels at the same time. pp 19–21

FIG 5 Frequency response of FSEM up to 26.5 GHz (without correction by peaking function)

can be fully utilized for the DUT instead of reserving them for the measuring instrument.

The largely digital signal processing Condensed data of Spectrum Analyzers FSEM/FSEK encompassing the resolution filters from Frequency range 20 Hz/9 kHz to 26.5/40 GHz 1 Hz to 1 kHz, detectors and the fully Amplitude measurement range –152/–142 to 30 dBm synchronous sweep ensures good Amplitude display range 10 to 200 dB in 10-dB steps, linear measurement reproducibility. Temper- Amplitude measurement error <1 dB (up to 1 GHz), <1.5 dB (1 to 7 GHz), ature and aging no longer have an <2 dB (7 to 18 GHz), <2.5 dB (18 to 26.5 GHz), <3.5 dB (26.5 to 40 GHz) effect. It is also noteworthy that meas- Resolution bandwidths 1 Hz/10 Hz to 10 MHz, in steps of 1/2/3/5 urement errors are not eliminated by Calibration amplitude, bandwidths, demodulator characteristic background calibration during opera- Display 24 cm (9.5“) colour or B/W TFT LCD, tion but only at the request of the user. VGA resolution So there will be no unpleasant surprises Remote control IEEE 488 (SCPI 1994.0) or RS-232-C caused by an automatically triggered Reader service card 152/02 calibration routine.

News from Rohde & Schwarz Number 152 (1996/III) 9 Articles

Calibration System TS9099 standard-frequency receiver. Of course, TS9099 can be connected to any frequency standard already used by Automatic test equipment the customer. All measuring units of the calibration system were selected so that calibration to ISO 9000 the DUT parameters to be calibrated can be determined at the prescribed Rohde & Schwarz has developed the powerful Universal Calibration System accuracy in the required ranges. TS9099 to enable fast calibration of a whole variety of RF measuring instruments in line with ISO 9000. This system was specially designed for signal generators, The system panel belongs to the basic test receivers and radiotelephone test assemblies for frequencies up to 2 GHz. The equipment of the automatic system; it frequency range can be extended at any time. serves on the one hand for mechanical

FIG 1 Calibration System TS9099 for signal generators, test receivers, radiotelephone test assemblies and similar equipment Photo 42 188

System architecture • signal generator, interfacing of a DUT and on the other • spectrum analyzer, for switching electrical signals from a Calibration System TS9099 (FIG 1) is • modulation analyzer, DUT to the measuring instruments and modular and upward-compatible, so • power meter, vice versa. Automatic and coordinated systems can easily be adapted to • precision attenuator, interconnection of the DUT with the different user test requirements. • system panel, various instruments within a calibration Compared to manual measurement, • controller with printer, routine is also established via the automatic calibration produces con- • software. system panel. siderable savings in time and additionally read and write errors are An uninterruptible power supply, peri- The test assembly is equipped with a avoided. The user can easily add pherals and small units as well as racks, selftest routine for checking and docu- new standard units to the basic equip- table and antistatic facilities complete menting the status of the system on ment and connect new DUTs to the the system. power-up. The reference standards system. used can be varied or exchanged. The System accuracy can be increased characteristic impedance used for RF The basic units of the calibration considerably by means of a rubidium measurements is 50 Ω. All RF connec- system (FIG 2) are: frequency standard regulated by a tions are BNC or N.

10 News from Rohde & Schwarz Number 152 (1996/III) Articles

Application Frequency Spectrum standard RF analyzer attenuator The TS9099 test system serves for Video Signal distrib. calibration of the following measuring generator amplifier instruments: Mod. RF Har- monics Modu- • signal generators, Multi- RF filter lation Generator meter voltmeter • test receivers, analyzer RF RF AF • RF millivoltmeters, • power meters, Scanner AF • radiotelephone test assemblies, Har- monics • spectrum analyzers, Switching matrix filter • frequency counters,

CISPR • attenuators, System panel generator • cables,

AF IF IF Track Ref. HF • probes. gen. Power VSWR VSWR Power splitter bridge bridge sensor Measurements are made of all required DUT parameters such as carrier fre- to DUT quency, S/N ratio, RF level and power, attenuation, reflection coefficient, FIG 2 Block diagram of Calibration System test data. The customer can also order amplitude, frequency and phase modu- TS9099 (options in yellow) yearly recalibration of the whole system lation, modulation frequency, AF level by an authorized center (eg Rohde & and AF total harmonic distortion as part

System software

The state-of-the-art system software is interactive (FIG 3), messages indicate incorrect operation. Menu guidance can be selected in German or English. FIG 3 The software is divided into two parts: Software basic software and user-definable interface library containing test routines. After system training, the user himself can write such routines. This library can be Schwarz Cologne Plant). In addition, it of the guaranteed specifications. After extended for any equipment with a is possible to conclude a maintenance calibration, the results are displayed on remote-control interface by the user or contract for regular inspection of the the screen of the system controller or Rohde & Schwarz. The DUT permitting, system at defined intervals. output on a printer. test sequences can be automated using Jon Pedersen the software and the system panel.

Condensed data of Calibration System TS9099 Process control is effected by a user- programmable controller with IEC/ Frequency range 10 kHz to 2160 MHz (can be extended) IEEE-bus interface. This networkable Level range –140 to 13 dBm (can be extended) Types of modulation AM, FM, ϕM controller can be equipped with Modulation frequency 1 Hz to 100 kHz storage media such as a streamer or Power measurement exchangeable harddisk. The measuring Power range 1 µW to 100 mW instruments, the DUT (if remotely con- Frequency 0 to 18 GHz trollable) and the computer are linked Test modes automatic, interactive via the IEC/IEEE bus or serial inter- Interfaces IEC/IEEE bus, RS-232-C, TTL faces. The controller steers the complete Reader service card 152/03 test sequence and stores and processes

News from Rohde & Schwarz Number 152 (1996/III) 11 Articles

System Processor MERLIN GR2000 harddisk and a PCI Ethernet card. Thanks to the modular design and versatile expansion capabilities, the Powerful processor stands system processor can be tailored to customer’s specific application needs. toughest conditions A wide variety of special, intelligent interface cards – eg fax, video frame System Processor MERLIN GR2000 is now replacing MERLIN GR856, which has grabber cards and encryption cards – been used for many special applications all over the world. MERLIN GR2000 are available. The passive backplane meets the same stringent environmental conditions but with more performance, a can accommodate up to eight plug-in more advanced bus system and better expandability than GR856. The enhanced cards. This design allows, among other price/performance ratio will make GR2000 an attractive proposition for new things, various CPU upgrades, and so applications, whether stationary or mobile. guarantees that the equipment is future- proof. The basic configuration provides five additional slots with PCI or ISA bus High computing power is a feature of for use under extreme environmental for further expansion. many PCs, but applications outside the conditions. It is of sturdy construction, comfortable office enviornment soon has low RF emission and low suscep- MERLIN version GR2000X is equipped separate the men from the boys. System tibility to EMI, is rackmountable and with EMC filters at its inputs and outputs Processor MERLIN GR2000 (FIG 1), operates reliably at temperatures from (FIG 2) and has special shielding. This which is of course compatible with the 0 to 50 °C. means low emission and low EMI industry standard, not only offers high susceptibility. RF shielding is effective computing power but is also suitable The basic model of GR2000 offers the both for radiated and conducted inter- usual performance characteristics of a ference and ensures interference-free standard PC: plug-in Pentium CPU card operation in two respects. On the one (currently 133 MHz), 16-Mbyte RAM hand, the system processor is not affect- FIG 1 Rugged System Processor MERLIN (expandable to 256 Mbytes), PCI VGA ed by strong EMI, and on the other, GR2000 can work effortlessly even in toughest 1 - conditions of vibration, impact and shock. graphics card, CD-ROM drive, 3 /2 the unit itself does not affect equipment Photo 42 561 inch disk drive, 1-Gbyte exchangeable sensitive to EMI (eg receivers). The

12 News from Rohde & Schwarz Number 152 (1996/III) Articles

filters at the serial and parallel inter- MERLIN has proven itself as a system faces make MERLIN ideal for use in processor and data terminal in a large applications that encounter extraordi- variety of applications implemented narily high levels of spurious emissions. by a great number of customers. Func- tioning as a data terminal, MERLIN The enclosure is of an extremely sturdy is operated with an ICOM-8 card. This construction. MERLIN can even be used provides eight serial channels, eases in environments exposed to water the workload of the CPU as it has its spray and – thanks to a pressure own processor, and also supports 5-bit cooling system with the air sucked in teletype mode (Baudot code). It allows via filters – in dust-laden atmospheres more instruments to be simultaneously too. The frame is reinforced and controlled than is the case with a con- designed to withstand extremely high ventional PC. MERLIN can thus utilize FIG 2 EMC filters in serial and parallel interfaces mechanical stress. This ensures of System Processor MERLIN GR2000X several media at a time and avoid de- problem-free operation under extreme Photo 42 568/1 lays in data transmission. An encryp- vibration, impact and shock loads, tion card can be fitted to make the which occur in vehicles and onboard transmission of sensitive data more ships. MERLIN will also operate secure. smoothly in rough terrain or on the access to the world of multimedia and Thomas Kneidel open sea. The 19-inch rack model, an simplifies the installation of modern alternative to the bench model, is parti- operating systems [1]. cularly suited for use in vehicles. MERLIN is compatible with all conven- Its EMC compatibility means that Sys- tional keyboards and monitors. Rohde tem Processor MERLIN can be used in & Schwarz also supplies special key- the immediate vicinity of radio trans- board and monitor versions for more mitters and their antennas. In conjunc- sophisticated requirements. tion with message-handling programs and special, intelligent interface A choice of power supplies is available modules, data transmission can be REFERENCES for System Processor MERLIN. As an implemented and combined [2] using a [1] Maurer, P.; Völker, K.: Multimedia communication with System Processor MERLIN. News alternative to the standard version, a wide variety of media such as HF, VHF from Rohde & Schwarz (1993) No. 142, power supply that satisfies the stringent and UHF radio links, telephone lines pp 27– 28 requirements for use onboard ships in and satellite links. The message- [2] Maurer, P., Völker, K.: Integration of modern line with STANAG 1008 is available. handling programs support the trans- data terminals in radioteletype networks. This version is immune to large voltage mission of fax files and vido stills [3] News from Rohde & Schwarz (1994) No. 146, pp 48 – 49 fluctuations and AC-line spikes of up to and optimize the use of e-mail net- [3] Hackl, J.; Kühn, G.: Colour video stills 2.5 kV. Moreover, the user can choose works. The familiar office environment speedily and reliably by shortwave. News between AC and DC power supplies. can thus be connected to various from Rohde & Schwarz (1992) No. 139, communication networks. pp 42–43 The exchangeable harddisk affords maximum flexibility and data security. As a boot medium, it enables fast and convenient loading of another operating system or of programs for Condensed data of System Processor MERLIN GR2000 various applications and requirements. Processor Sensitive information can be conven- CPU plug-in Intel Pentium processor board, iently stored in a safe place. Special 133 MHz, 16 Mbytes Graphics card PCI VGA, 2-Mbyte RAM storage media are available for Exchangeable harddisk 1 Gbyte applications subject to extremely high Drives 3.5-inch disk, 1.44 Mbytes; CD-ROM levels of vibration. Interfaces Standard I/O 2 x COM, 1 x LPT, filtered I/O interfaces (GR2000X) With the CD-ROM drive, which is in- Free slots 1 x PCl, 3 x ISA, 1 x PCl/ISA cluded as standard, Rohde & Schwarz Network card PCl Ethernet is taking a forward-looking approach Reader service card 152/04 to industrial PCs. This feature provides

News from Rohde & Schwarz Number 152 (1996/III) 13 Articles

Series 200 and 400U radio equipment Remote Control and Monitoring System RCMS

Innovations in ATC radio- The RCMS especially developed by Rohde & Schwarz for Series 200 radio communications: RCMS and equipment [1] offers the user different ways of remote control (interfaces, 8.33-kHz channel spacing transmission techniques) as well as integration of auxiliary tools (options, Reliability has top priority in ATC radiocommunications as human lives are at add-on units) and user-friendly software stake. Central and flexible remote control and monitoring systems (RCMS) as well (FIG 1). Any ATC radiocommunications as the 8.33-kHz channel spacing planned for 1998 contribute to safety. For this system is subject to customer-defined reason Rohde & Schwarz has logistically upgraded its ATC radio equipment: specifications and constraints for all its Series 200 now comes with RCMS and 8.33-kHz channel spacing. Series 400U subsystems such as radio, operation is also available with 8.33 kHz. Thus the customer is already provided with and control or voice switching. RCMS ultramodern and future-proof solutions. meets these requirements thanks to its

FIG 1 VHF system with eight single-channel features and measures at the device flexibility and offers the system planner Receivers EU231A and single-channel Trans- and system level. They include low different techniques and special fea- mitter SU251 as well as channel-specific RCMS window (example: channel 003/130.1 MHz, unit downtimes, equipment redun- tures. separate transmitters and receivers each in auto- dancy, frequency planning and solu- matic 100% standby mode) Photo 42 570 tions to collocation problems. Modern Parallel technique. This allows normal systems also call for central control operation of the radio equipment via and monitoring with special functions conventional interfaces. to ensure link reliability, convenience The technical safety of an ATC radio and cost efficiency calculated over the Digital REM BUS technique. The new system depends on a variety of system’s lifetime. model (.03) of REM BUS Drive Unit

14 News from Rohde & Schwarz Number 152 (1996/III) Articles

Audio inband technique via four-wire Reorganization of REM BUS Test generator VHF-UHF VHF-UHF Test generator telephone lines. With this option the frequency management (RF) multicoupler multicoupler (RF) leasing fees for point-to-point telephone AF/PTT RF RF AF/PTT

Receiver Receiver lines, especially for transceivers, can Increasing air-traffic volume and the pre- ED/EU2... ED/EU2... RX RX be reduced considerably. A carrier fre- dicted frequency demand for voice and REM REM BUS BUS quency (2040 or 2440 Hz) is nested radio data transmission in the VHF range

into the two bidirectional audio spectra from 118 to 137 MHz create the need

(FIG 3). The combination of 4FSK and for fast and radical reorganization of

AM modulation as well as the use of a frequency management. The operation-

digital 24-bit signal processor with high al requirement for undisturbed channels 7 14 computing power of 20 MIPS allows would not be met by merely halving the Voice communication REM BUS Drive Unit Voice communication switching system GV201(.03) switching system around 20 remote control and monitor- present channel spacing from 25 kHz AF/SQL distribution RS-232-C AF/SQL distribution ing functions including the time-critical to 12.5 kHz, so the International Civil to operators to operators

Modem functions PTT and AGC/squelch to be Aviation Organization ICAO has come Receive station modulated and demodulated. to the following decisions after tests conducted by the British ATC authority Hybrid technique. The above-men- (CAA/NATS) as well as feasibility stud- Filter/combiner (multicoupler) network tioned techniques can also be com- ies and specifications by different com- AF/PTT RF RF AF/PTT bined for special system requirements. mittees (eg EUROCAE, ETSI) with active Transmitter REM BUS Transmitter SD/SU2... SD/SU2... participation by Rohde & Schwarz:

Thanks to these remote control and • A VHF channel spacing of 8.33 kHz

monitoring system features, technical (voice) and 25 kHz (voice and data)

supervisors benefit from the follow- will be introduced.

ing: • Operation in Europe will be

• central configuration of the radio launched on 1 January 1998 in se- 7 14 system, lected air corridors. Voice communication REM BUS Drive Unit Voice communication switching system GV201(.03) switching system • continuous tests, • Modulation will be AM A3E (double- AF/PTT distribution RS-232-C AF/PTT distribution • display of station and channel status, sideband modulation, DSM). to operators to operators Modem • manual and automatic radio redun- • Ground single-channel radio equip- Transmit station dancy, ment will be for 8.33 or 25 kHz. Telephone line Telephone line • RF tests at any operating frequency Modem Modem of receiving systems, RS-232-C • remote error analysis partly down to multiple COM card Highly decoupled antenna system Workstation Supervisor the functional unit, • permanent result logging, • efficient deployment of personnel. FIG 2 Digital control and monitoring system (RCMS) for separate VHF/UHF transmit and re- Filter/combiner (multicoupler) network ceive stations with 14 radio channels All this is not limited to the airport but RF(TX) RF(RX) Transceiver can be used country-wide: thanks to AF 2 TX/RX A modems or the inband technique the 2 F1 technical supervisor can be contacted 2 TX/RX B F1 practically anywhere and at any time. 2 2 TX/RX A Rohde & Schwarz is offering special 2 F2 4 support for the supervisor with Mainte- AF distributor nance and Service Package X-LINK Radio station GV201 allows control at PC COM (Express Link). With this extremely Telephone line interfaces via RS-232-C (FIG 2). The economical product, software updates 4 4 Supervisor corresponding RCMS software can and functional checks (error analysis) Control Control Control for for be used for single-channel and multi- of a radio system are performed at TX/RX TX/RX A/B A channel Series 200 radio equipment Rohde & Schwarz headquarters in F1 F2 F8 and is downward compatible with Munich via telephone lines after re- AF, PTT, SQL from/to operators via voice communication switching system single-channel systems installed so far. ceiving the customer’s request and per- Altogether 30 control and monitoring mission to access the equipment – no FIG 3 Analog (AF) inband RCMS for VHF-UHF functions can be transmitted per trans- matter whether the airport is in the radio station with transceivers with one redun- ceiver channel. South Pacific or in Siberia. dant (F1) and one normal channel (F2)

News from Rohde & Schwarz Number 152 (1996/III) 15 Articles

• Airborne transceivers will have generator for receiving systems using an option for 8.33-kHz transmitters and switchover capability between 8.33 8.33-kHz channel spacing is another transceivers. The operating software for and 25 kHz. new option. the radio equipment is of course also designed for 8.33-kHz operation. Switchover between 8.33 and 25 kHz Series 200/multichannel VHF and also has to be possible for ground VHF UHF radio equipment that can be Optimum coordination between all multichannel radio equipment such as switched to any frequency within the persons involved in introduction of the for emergency standby or special tasks 25- or 8.33-kHz channel spacing is cur- 8.33-kHz channel spacing (ATC opera- (SAR, defence). rently being developed (first digital ATC tors, airlines, service, supply industry, receiver) and will be available in time etc) guarantees in these times of reor- ATC operators in key European areas before 8.33-kHz operation is started. ganization that restrictions of air traffic (southern part of Great Britain, the or impairment of flight operations in the Benelux, France, Germany, Switzer- New in Series 200/RCMS too: REM parallel 25-kHz ATC sectors are re- land, Austria and northern Italy) are BUS Drive Unit GV201 and RCMS duced to a minimum. Rohde & Schwarz now asked to invest on the basis of the software are of course tailored to the contributed to this by committing itself decisions taken with a view to imple- new techniques. Thus they comprise im- early to the definition phase and by menting the new frequency channels in portant components and performance developing, producing and supplying ground radio control centers. Airlines features for PC-controlled RCMS. One new radio equipment in good time. will have to retrofit part of their fleets. of the most attractive innovations of After just one year of development, the RCMS is Service and Maintenance 8.33-kHz technique could be launched The 8.33-kHz requirement has in par- Package X-LINK mentioned already. in June 1996 with 100 units from each ticular implications for the following of the Series 200 and 400U radio components: As part of Series 400U, which is based equipment. • synthesizers for transmission, recep- on the successful Series 400 [2], Rohde Hans-Günther Klarl; Martin Kessler tion and test (channel setting and & Schwarz offers the following new 25- higher frequency stability), and 8.33-kHz-compatible unit types for • receivers (higher selectivity through civil and military multichannel appli- REFERENCES IF crystal filters), cations: Transceivers XU452U8 (VHF) [1] Klarl, H.-G.: Series 200 VHF single-channel • transmitters (lower modulation upper and XT452U8 (VHF/UHF), Transmitters radio equipment – The new dimension in ATC communication. News from Rohde & cutoff frequency), SU452U8 (VHF) and ST452U8 (VHF/ Schwarz (1993) No. 140, pp 4–7 • operation and display (adaptation UHF) as well as Receivers EU458U [2] Haller, J.: Series 400 VHF/UHF radio sets of hardware, device-specific firm- (VHF) and ET458U (VHF/UHF). An for air-traffic control. News from Rohde & ware and system software). AF/telephone Interface is available as Schwarz (1982) No. 96, pp 4–7

Innovations in Rohde & Schwarz radio Innovations in Series 200 and 400U radio equipment equipment Series 200 VHF single-channel receiver 8.33- or 25-kHz spacing, The new units of Series 200/single- and transceiver depending on version channel comprise a new, universal VHF single-channel transmitter 8.33 kHz (with Modulator Extension GM201C8) or 25 kHz synthesizer. Models of VHF Receiver Multichannel units currently being developed EU231A/D and VHF Transceiver REM BUS Drive Unit GV201 (.03) RS-232-C interface for PC-COM cards, XU221/XU251 are now available for conversion to REM BUS 8.33 or 25 kHz with corresponding IF Operating Software GC201-S (.03) combined version for 8.33 kHz and 25 kHz filters. For the transceivers, a modulator Test Generator GT231T1 (.22) 8.33-kHz and 25-kHz compatible, extension is additionally provided for single-channel and multichannel units for the 8.33-kHz specific frequency 4-carrier offset according to ICAO with standard synthesizer response. This modulator extension for Series 400U 8.33 kHz is available as an option VHF + VHF/UHF multichannel receiver 8.33 kHz/25 kHz switchover for VHF Transmitters SU221/SU251. VHF + VHF/UHF multichannel 8.33 kHz/25 kHz switchover (with GI419U) transmitter and transceiver To guarantee retrofitting from 25 to AF/Telephone Interface GI419U module for 8.33-kHz compatible transmitters and 8.33 kHz (or vice versa) with mini- transceivers mum logistics and service, the IF filters Operating Software GB406-S combined version for 8.33 kHz and 25 kHz as well as the modulator extension Reader service card 152/05 are equipped with connectors. A test

16 News from Rohde & Schwarz Number 152 (1996/III) Articles

TV Test Receiver Family EFA multiplied by the sound carrier and the intercarrier thus obtained is selected and frequency-demodulated. The Top fit for advantage of this is that incidental phase modulation from local oscillators digital television as provided in every TV receiver does not appear in the demodulated audio Small-size, compact, future-oriented, upgradable – this is how TV Test Receiver signal, whereas that from the vision Family EFA shows its true self. With this family Rohde & Schwarz has created modulator is reflected in the demodulat- a test platform that can easily keep pace with rapid developments in television. ed audio signal. TV Test Receiver EFA Before the official start of digital video broadcasting, Rohde & Schwarz can detects this interference and is therefore already offer the world’s first demodulator for QAM signals which is able to suitable for measuring and monitoring perform all the measurements required on cable digital channels. An analog the sound quality of received signals. TV test receiver – either broadband or selective – is available for monitoring The frequency-demodulated audio sig- the previous TV channels. Digital and analog functions can also be combined in a nals are brought out at balanced out- single unit, which can be expanded by adding options. puts. For measuring incidental carrier

With its modular design the compact 12-kg TV Test Receiver EFA (FIG 1) is extremely versatile and made for easy upgrading. In addition to the micropro- cessor module fitted as standard and the modules of the respective basic EFA model, another five functional modules can be accommodated (FIG 2). Every user can thus configure a model to suit his specific requirements or upgrade the basic model at a later date.

Basic models

The first member of the EFA family is the analog TV test receiver with selective receiver section. It receives amplitude- modulated TV signals to all common standards, selects the TV channel and converts it to IF. Picture and sound signals are then demodulated by the analog demodulator. Sound is demodulated according to the intercarrier method, where the vision carrier is

FIG 1 TV Test Receiver EFA, allround specialist for measurements on analog and digital TV signals – seen here in headend station Photo 42 575

News from Rohde & Schwarz Number 152 (1996/III) 17 Articles

Receiver section with tracking selection IF input

IF vision Analog demodulator Video Selective Attenuator Selective IF sound for vision and Audio (FM) RF input 0 to 55 dB receiver section intercarrier sound

Receiver section of broadband demodulator model IF input NICAM IF demodulator Broadband Attenuator Broadband RF input switch receiver section

MPEG2 DSP analysis IF transport QAM demodulator stream RS-232-C Micro- IEC/IEEE bus LCD processor Printer IF output

FIG 2 Block diagram of TV Test Receiver EFA An optional NICAM demodulator is Further functional modules can be add- (basic models shown in blue, functional modules available for decoding the digital ed to the broadband TV test receiver in yellow). Receivers can be configured to suit specific application. QPSK-modulated sound carrier to just as to the selective one. NICAM 728 standard. Further options (functional modules) are in develop- Another member of the EFA family is the ment. DVB test receiver with QAM demodulator. It is used for measurements on In addition to the model with selective digital channels in cable-TV networks. receiver section, the analog TV test re- Instead of an analog demodulator, a phase modulation (ICPM), TV Test ceiver is also available with a broad- demodulator for quadrature amplitude- Receiver EFA provides a quadrature- band receiver section. In single-chan- modulated (QAM) signals – fully com- demodulated vision carrier signal. In nel applications it is used for measure- patible with the DVB standards [1] – is conjunction with an internal or external ments directly on the source. Typical used in this case for processing the zero reference pulse and an oscillo- examples are measurement of the DVB-C channel converted to IF. The out- scope or video analyzer, it allows quality data of TV transmitters and put signal is then in the form of a serial quantitative determination of ICPM. transposers in single-channel mode as or parallel MPEG2 transport stream [2]. well as monitoring radiated RF sig- The analog TV Test Receiver EFA meas- nals. A Nyquist demodulator ensuring The QAM demodulator measures the ures all important RF transmission pa- system-compatible demodulation of the following parameters separately, per- rameters and displays them on an generated signals is used for these forms calculations [3] and outputs LCD (FIG 3): applications. the results on its display in line with re- • power and voltage of vision carrier quirements of the DVB Measurement in dBm, dBpW or µV/mV, dBµV, Group [4]: • vision carrier frequency, • constellation diagram, • vision/sound carrier level ratio, • RF level, • vision/sound carrier frequency spac- • signal/noise ratio, ing, • bit error rate, • FM sound carrier deviation, • amplitude imbalance, • FM pilot deviation, • carrier suppression, • pilot frequency. • phase error and phase jitter, • modulation error ratio (MER). Depending on the model, Test Receiver EFA demodulates TV signals of stan- The constellation diagram (FIG 4), dards B/G, D/K, K1, I or M/N. In ad- which is graphically displayed and dition to a constant video group delay, mathematically evaluated by a signal implemented in each receiver model, processor, supplies the most important TV Test Receiver EFA features group- information on QAM signals. To ensure delay correction that depends on the the required statistical reliability for respective standard and is available FIG 3 Screen display for analog TV test receiv- the evaluated parameters, about for all worldwide TV standards. er mode 1,000,000 I/Q values are considered.

18 News from Rohde & Schwarz Number 152 (1996/III) Articles

The QAM demodulator can be fitted Uses REFERENCES with up to three SAW filters so that not [1] European Telecommunications Standards In- only 8-MHz QAM packets can be pro- The broadband TV test demodulator is stitute ETSI: Digital broadcasting systems for television, sound and data services; framing cessed with 64QAM which is almost ideal for the precise measurement and structure, channel coding and modulation standard today, but also packets of monitoring of the quality data of TV cable systems. Draft prETS 300 429 (1994) 4 or 2 MHz. Thanks to the versatile transmitters and transposers. The selec- [2] DVB Technical Module’s Ad-hoc Group Phys- configuration possibilities of the QAM tive receiver model is required for ical Interfaces: Interfaces for CATV/SMATV demodulator, 4QAM to 256QAM can measurements in cable-TV networks. headends and similar professional equipment. 10th working draft DVB-PI-154 (1995) be selected for all current methods. For this application the combinational [3] Balz, C.: Effiziente Ermittlung von Qualitäts- Among many other features, error pro- unit with analog and QAM demodula- parametern quadraturamplitudenmodulierter tection can be switched off and the roll- tor is recommended. The powerful test Signale beim Digitalen Fernsehen (DVB). off factor selected. A built-in noise receiver family is of course also suitable Fernseh- und Kinotechnik No. 5 (1996), generator is available for determining for applications in development labs, pp 249–252 the noise margin. quality management and production [4] DVB Technical Module’s Ad-hoc Group on Test and Measurement: MG 66 Rev. 4 monitoring. (04/1996) It is of course possible to equip the test receivers for the measurement of both With TV Test Receiver Family EFA from analog and digital TV signals. The mod- Rohde & Schwarz an enormous step has been made towards digital video broadcasting, whilst taking full account of previous TV standards. The program will be continuously expanded by new functional modules to open up further sectors of digital television. Christoph Balz; Ernst Polz; Walter Fischer

FIG 4 Constellation diagram in QAM demodulator mode; result hold time adjustable from 2 ms to infinite Condensed data of TV Test Receiver Family EFA Frequency range 47 to 862 MHz Inputs RF, IF Input impedance, RF 50 or 75 Ω ular design allows optimum customiza- Input voltage range tion and the configurations described Selective analog TV test receiver 30 µV to 1000 mV above are only a few among many. Selective QAM receiver 100 µV to 700 mV Broadband analog TV demodulator 10 to 2500 mV Outputs IF, controlled Interfaces Loudspeaker, headphones adjustable volume, can be switched off Interfaces IEEE 488, RS-232-C, Centronics EFA features a large LCD for display of Nyquist test receiver user information, measured values and Inputs external zero reference pulse graphs. Hardkeys and softkeys ensure Outputs video, Q signal, audio balanced, audio unbalanced, headphones great ease of operation. The micropro- QAM demodulator cessor module provides a variety of Specifications compatible with DVB guidelines interfaces; the receivers can be remote- Order of QAM 4, 16, 32, 64, 128 or 256 ly controlled via IEEE bus or RS-232-C Rolloff factor 0.15 to 0.30, selectable Internal noise generator 12 to 62 dB C/N, adjustable interface and come with a printer con- Outputs parallel or serial MPEG2 transport stream, nector. The demodulated sound can serial data/clock before error correction be monitored via a built-in loudspeaker Reader service card 152/06 or headphones.

News from Rohde & Schwarz Number 152 (1996/III) 19 Articles

MPEG2 Generator DVG and pact alternative to expensive MPEG2 MPEG2 Measurement Decoder DVMD encoders with multiplexer and external standard generators. It is ideal for testing and commissioning MPEG2 trans- Test equipment for digital TV mission links and may be used as a substitution signal source in the case of in line with MPEG2 program failures or for adjusting and testing decoders and TV sets. Since A new TV standard is about to be launched worldwide. Thanks to digital technol- DVG takes its signals from RAM and ogy many more programs can now be broadcast and flexible scrambling offered they can be played back time and time without the need for more bandwidth. Rohde & Schwarz supplies the test equip- again without any “wear and tear”, the ment that guarantees the quality of these digital TV transmissions received via a generator is predestined for applica- set-top box: MPEG2 Generator DVG and MPEG2 Measurement Decoder DVMD. tions where continuous operation is required. These features make DVG a practical, high-availability signal source wherever MPEG2 signals are to be found.

MPEG2 signal structure MPEG2 signals are digitized video and audio signals that have undergone considerable data reduction. The MPEG2 standard permits several data reduction methods to be used [1]. A main feature of video data compression is that in most cases only data variations (differential video) are transmitted. To meet this requirement, the signals generated by DVG consist of continuously repeated moving picture sequences. To avoid discontinuities at the end of each sequence, the following should be

FIG 1 borne in mind: the programs in the MPEG2 Generator transport stream are assigned different DVG and Measure- presentation time stamps (PTS) and ment Decoder DVMD decoding time stamps (DTS), enabling with TV monitor showing decoded the decoder to determine the sequence picture and menu of the pictures to be transmitted and display to synchronize them with the accom- Photo 42 498/1 panying audio signals. Another time marker, the program clock reference (PCR), is used as a reference. If the same unchanged sequence were per- MPEG2 Generator DVG several programs, each consisting of manently repeated without time stamps, several substreams (video, audio and there would be “time jumps” and all MPEG2 Generator DVG (FIG 1) is a data signals). Programs are no longer down-stream equipment would have to signal source for MPEG2 transport combined at RF frequencies after the be resynchronized. The time stamps for streams. The structure of these streams modulator, as is the case with con- each program are therefore continually and the data reduction methods em- ventional TV techniques, but produced updated in DVG and a continuous ployed were developed and standard- at the baseband in the form of signal like that produced by an en- ized by MPEG (Moving Picture Experts a program and signal multiplex. coder is generated, although the scene Group) and the DVB (Digital Video is repeated over and over again Broadcasting) project. A main feature DVG generates these multiplex signals (FIG 2). Only the use of continuous of the transport stream is that it contains and is a favourably priced and com- transport streams such as these ensures

20 News from Rohde & Schwarz Number 152 (1996/III) Articles

printer or VGA monitor can be connected. In this case all the information in the transport stream is available at the PCR PTS press of a button. In addition to the DTS RS-232-C interface, DVG also has a PCMCIA adapter. This adapter, the FIG 2 Continuous PCR, PTS and DTS time stamps in repeated sequences same as that provided on every laptop, may be used for connecting SCS interfaces, network cards, exchangeable harddisks or a CD-ROM drive for storing signals. smooth and reliable tests on MPEG2 areas rotating in each field and a The selected transport stream is avail- terminal equipment and transmission white spot moving backward and able at three DVG outputs. The TS par- links. forward across 24 frames displayed on allel output on the front panel is a syn- the screen. The loss of frames during chronous, parallel LVDS interface. The transmission is indicated by irregular level at this output was set to the upper Signals generated by DVG flicker of the rotating areas and by limit of the DVB standard A010 [2] so As FIG 2 suggests, some of the DVG a halting movement of the white spot. that at least two devices can be con- transport streams also contain live se- The moving spot may also be used nected. Two devices may also be con- quences, ie video and audio signals, for delay measurements. nected to the two serial, asynchronous whose quality cannot be determined by outputs (TS ASI), one on the front, the measuring equipment but only by eye. The transmission of data in the MPEG2 other on the rear of DVG. These two As data-reduced signals have little or multiplex is still an open question – even types of interface have now become no redundancy, even a small number among broadcasters. Many data ser- the de-facto standards. of bit errors may impair transmission vices could certainly be envisaged, but quality, particularly in areas where the viewers will still, first and foremost, picture is changing. Therefore live want teletext facilities in the future. So sequences are essential for checking the transmission of teletext data has to that transmitters and decoders are oper- be checked as well. In this case DVG ating correctly. inserts teletext pages in the form of data packets into the transport stream In addition to transport stream transmis- multiplex. sion, analog signal processing in the terminal equipment also has to be Even all these signals do not exhaust checked. D/A conversion in the decod- the capabilities of DVG. When a key- ers and adjustments of the picture board, a mouse and a VGA monitor geometry in TV sets are normally tested are connected, DVG becomes a PC with video stills and the analog sound- with additional signal generation fea- signal path has to be adjusted or tested tures. For instance, with the aid of the as well. DVG provides all essential Stream Combiner® program packet, test patterns and analog sound signals the MPEG2 specialist is able to gener- FIG 3 Rohde & Schwarz codec test pattern required for these tests. The Rohde & ate his own signals and make special Schwarz codec test pattern (FIG 3) and settings in the system information data. the standard sound sequence CCITT Even errors may be included in the 0.33 are ideal for fast, automatic tests transport stream. with video and audio analyzers.

This test pattern created by Rohde & Simple operation and Schwarz not only covers all ana- multifunction interfaces All these signals, interfaces and con- log measurements but simultaneously All the main configuration data of the figuration capabilities make DVG not checks whether the MPEG2 trans- transport streams are shown on the in- only a compact but also a universal mission is OK or whether only the last tegral LCD. Normally the data shown MPEG2 signal source and thus an decoded picture is displayed by the by the LCD will be sufficient, but if more essential tool for measurements to decoder. This check uses four white detailed information is required a MPEG2 and DVB.

News from Rohde & Schwarz Number 152 (1996/III) 21 Articles

MPEG2 Measurement on a specific or any type of error Decoder DVMD (trigger on error) is also based on this monitoring system. In this case the By monitoring and analyzing the transport stream before and after the MPEG2 transport stream, DVMD trigger event is recorded and can be (FIG 1) performs a completely new kind output via a serial interface for further of measurement task that has arisen analysis. because of the introduction of digital TV. The measurements are intended to This online measurement capability ensure smooth interworking of all com- allows the network operator in partic- ponents in a DVB transmission network. ular to determine the data rates of the DVMD also provides information about FIG 4 Error statistics from MPEG2 Measure- transport stream, programs and ele- ment Decoder DVMD the contents of the transport stream mentary streams, which is a significant and decodes the programs contained form of analysis. Data rates indicate in them. Results of the protocol analysis the network load and determine trans- can then be compared to the decod- mission costs. They are not derived ability of video and audio signals. The from service information in the trans- measurement decoder not only pro- port stream but computed online. vides comprehensive information about the quality of the transport stream but makes the new technology transparent Decoder unit: so that reliable use is ensured. essential enhancement plus second test set DVMD combines a test set and decod- No way out for errors: er in one unit and uses decoding as an protocol monitoring online FIG 5 DVMD test report additional test method. As a result you Comprehensive, highly integrated can directly “hear and see” what results hardware combined with a powerful mean. Video and audio signals are signal processor system is the basis available in analog and digital form: for continuous and comprehensive • analog video in PAL, NTSC or monitoring and analysis of a transport SECAM (two outputs), stream. Analysis is always performed • analog video in Y and C, in realtime. Not only are substreams • digital serial video (ITU-R 601/ or individual programs monitored, the 270 Mbit/s), integrity of the whole transport stream • analog audio L /R (two outputs is checked. This makes it possible to each), demonstrate that timing is correct and • digital audio AES/EBU. contents of protocols and parameter values are complied with during trans- The audio-visual content of a transport mission as well as with lab measure- FIG 6 Data rate of all programs in transport stream is laid bare and can be passed ments. stream determined by DVMD on in decoded form.

Monitoring and analysis of the transport stream are based on the guidelines No restrictions for laid down by the Measurement Group scrambled programs of the Technical Module of the Euro- while tests of the third group monitor DVMD may also be used for scram- pean DVB project [3]. The tests defined service information for compliance with bled programs. These have no effect in the guidelines are classified in terms DVB guidelines. on protocol monitoring since the of three priority groups according to relevant data are not scrambled. A their importance. First-priority tests All three groups are taken into account common interface defined by the check synchronization of the transport by DVMD when the transport stream is DVB project [4] is available for decod- stream and program access. Tests in monitored. If an error occurs, detailed ing scrambled programs. With the the second priority group identify information that depends on the type of aid of a key card, obtainable from transmission errors and check time error is output so that the error source the broadcaster, even scrambled pro- references in the elementary streams, can be pinpointed. The ability to trigger grams can be analyzed.

22 News from Rohde & Schwarz Number 152 (1996/III) Articles

Menu-guided operation REFERENCES and display [1] ISO/IEC 13818: Generic Coding of Moving [3] DVB-TM 1601: Measurement Guidelines for Pictures and Associated Audio Information DVB Systems The LCD of DVMD is used to operate it [2] DVB Document A010: Interfaces for CATV/ [4] DVB-TM 1341: Common Interface Specifi- SMATV Headends and Similar Professional cations for Conditional Access and other and display information. A TV monitor Equipment Digital Video Broadcasting Decoder Appli- can also be used for this purpose via cations the OSD function (onscreen display). The OSD function displays the coloured menus with the desired transparency in the decoded picture (FIG 1). This gives a clear display of detailed measurement results. The following test menus are available: • joint display of error counters for all monitored parameters (FIG 4), • preparation of a detailed test report (FIG 5), • display of all programs in the transport stream with information on program structure, data rates and scrambling (FIG 6), • list of all elementary streams in a pro- Condensed data of MPEG2 Generator DVG and gram plus associated data rates. MPEG2 Measurement Decoder DVMD

LEDs on the front panel of DVMD DVG Output signals transport stream to ISO/IEC 13818-1 directly display each of the first-priority Length of transport stream packets 188/204 bytes (settable) tests (TS_sync, Sync_byte, PAT, Continu- Data rate of transport stream 0.6 to 54 Mbit/s (settable) ity_count, PMT [3]) and the main tests Total data rate of in the second priority group (Trans- elementary streams up to 15 Mbit/s port_error, CRC). All other tests in the Total data quantity of second and the third priority groups are elementary streams 100 Mbits indicated by a single LED. Stored signals approx. 20 transport streams (MP@ML), moving picture sequences, test patterns, test tones, teletext Signal outputs 1 x TS parallel (to DVB-A010), User-friendly remote control 2 x TS ASI (to DBV-A010) DVMD offers full remote control. All Interfaces ports for PC peripherals settings and queries can be made via a serial interface. In addition, data DVMD contained in the transport stream Input signals transport stream to ISO/IEC 13818-1 may be read and analyzed further. Length of transport stream packets 188/204 bytes This applies to data sections with Data rates of transport stream 0.6 to 54 Mbit/s syntax errors (trigger on error) as well Signal inputs 1 x TS parallel (to DVB-A010), 2 x TS ASI (to DVB-A010) as to filtered data components (eg Tests to DVB-TM 1601 1st priority (Ts_sync, Sync_byte, PAT, packets of a substream or packets with Continuity_count, PMT, PID) adaptation field). 2nd priority (Transport_error, CRC, PCR, PCR_accuracy, PTS, CAT) 3rd priority (NIT, SI_repetition, DVMD offers more than just access to unreferenced_PID, SDT, EIT, RST, TDT) a new TV measurement technique. It Other tests trigger on error, data rates of transport provides comprehensive information stream or substreams on structure and syntax and allows Decoder outputs Video 2 x CCVS, 1 x Y/C, 1 x ITU-R 601 detailed monitoring and analysis of Audio 2 x analog audio L/R (LEMO), the protocols used for any MPEG2 mul- 1 x AES/EBU tiplex data stream. Interfaces RS-232-C Reader service card 152/07 Michael Fischbacher; Harald Weigold

News from Rohde & Schwarz Number 152 (1996/III) 23 Articles

100/200-W Solid-State DAB Transmitter NL5010/5020 Since a new type of amplifier is used in the transmitters, the output bandpass filter for limiting out-of-band transmis- Terrestrial broadcasting sions may also be integrated in the rack. This was not possible with pre- of digital audio in L band vious transmitter models. There is also ample space to accommodate a GPS The 100/200-W Solid-State L-Band DAB Transmitter NL5010/5020 completes the frequency standard (option). range of Rohde & Schwarz DAB transmitters which cover all DAB frequencies. The new audio broadcast transmitter operates in the frequency range 1452 to Function 1492 MHz and fully complies with the requirements made on a modern DAB transmitter. Depending on the type of ETI (ensemble transport interface) to the transmitter site, the signal from the satellite demodulator or from another source is fed The international specification for the The L-band Transmitters NL5010 to COFDM Modulator MCM01 (FIG 2), DAB (digital audio broadcasting) (100 W) and NL5020 (200 W) were which π/4 DQPSK-modulates the system (ETS300401), which was pub- developed on this basis and now com- data onto carriers, the number of which lished in 1994, was prepared by plete the line of Rohde & Schwarz DAB is determined by the selected DAB renowned research institutes, sound transmitters. Thanks to their design, mode. This baseband DAB signal with broadcasting corporations and indus- quality, and operating philosophy spectrum width of approx. 1.5 MHz trial companies as part of the Euro- they fit perfectly into the range of well- and center frequency of 2.048 MHz is pean project EUREKA 147. From the proven Rohde & Schwarz transmitters applied to Exciter SD100A2. After very beginning Rohde & Schwarz [2]. The main components of the mixing to a fixed IF (38.902 MHz) the played a decisive role in this work [1]. transmitters are COFDM Modulator signal is amplitude- and phase-equa- MCM01 [3], Exciter SD100A2, Ampli- lized and then finally converted to an fier VL5010, primary-switched Power L-band frequency in the range 1452 to FIG 1 100-W Solid-State DAB Transmitter NL5010. 200-W model contains second amplifier Supply IN916, power distribution and 1492 MHz (setting increment 25 Hz). module in transmitter rack. This type of transmitter a high-pressure fan, which are all de- The RF signal is then amplified in the has already been in use for more than one year at Wendelstein as part of world’s largest DAB signed as plug-in units and accom- exciter and routed to the transmitter network. Photo 42 530 modated in a transmitter rack (FIG 1). output stage, directly in the 100-W

24 News from Rohde & Schwarz Number 152 (1996/III) Articles

DAB signal DAB signal pressure fan provides adequate cool- 2.048 MHz L Band ing for the power supply and amplifier. ETI signal Output Antenna output COFDM Output Exciter bandpass 100/200 W modulator stage All components are designed so that a filter Output directional fairly small, coarse air filter is sufficient. coupler Switch-mode power supply Measured power DAB transmitter amplifier GPS Remote- Switch-mode frequency control unit power supply The DAB signal is a multicarrier signal standard Pilot frequency 10 MHz with its information in the relative phase π Main switch of the /4 DQPSK-modulated carriers. With certain information it is possible GPS antenna for many carriers to have the same phase. Carrier amplitude reinforcement FIG 2 Block diagram of 100/200-W L-band transmitter occurs and, in critical cases, an excep- tionally high input signal is applied to transmitter or via a power splitter in the If the DAB transmitter is to be part of the output amplifier for a short period. 200-W transmitter. a single-frequency network (SFN), the The output amplifier must, therefore, be required frequency stability of each highly linear over the entire voltage Transmitter operation (eg on/off, power and frequency setting, deemphasis) is menu-guided and performed from the Control voltage exciter using a backlit LCD and the keypad. The exciter also displays the status Directional coupler of all relevant transmitter functions and is used to monitor and control the transmitter. A remote-control unit includes floating contacts for transmitter switch- RF signal RF signal on and switch-off as well as for monitor- from exciter to directional Feedback coupler ing the operating status of the whole preamplifier transmitter. FIG 3 Amplifier of Solid- State DAB Transmitter NL5010 Power splitter 3-dB coupler

transmitter (∆f/f = ±1 x 10–9) must be swing so that intermodulation products obtained from a highly accurate GPS inside and outside the useful frequency frequency standard. This standard range are minimized. supplies a 10-MHz pilot frequency and makes the reference frequency avail- To meet these requirements Rohde & able to any site within the network. A Schwarz developed the solid-state directional coupler at the antenna L-band DAB Transmitter Amplifier output feeds the RF test output and the VL5010. Even without an output band- forward and reflected power that is pass filter, the compensated amplifier coupled out and displayed on the has intermodulation suppression of exciter. 30 dB. The RF signal from the exciter is routed via a preamplifier, a power split- The primary-switched power supply ter and two further amplifier stages with self-engaging connectors provides each with four parallel push-pull ampli- all the voltages needed by the DAB fiers (FIG 3). At the output of these par- transmitter. The power distributor con- allel circuits, a proportion of the power tains a contactor for switching on the is coupled out by a directional coupler high-pressure fan and a phase monitor and fed to the gain control in the pre- which sends the “power supply amplifier. If a transistor in a particular present” message for the transmitter’s module fails, protection circuits in the three-phase power supply. The high- module prevent a power increase in the

News from Rohde & Schwarz Number 152 (1996/III) 25 Articles

0 dB ponent supplier in all DAB projects to -10 date (ARD pilot project, Deutsche Tele- Critical mask

r Non-critical mask kom, Australia, Switzerland, Sweden, -20 etc) and so has made a major contribu- -30 tion to their success.

-40 Rainer Steen; Johannes Steffens

-50

-60

-70 Level ratio of in-band to out-of-band powe -80

-90 FIG 4 Specification 0 0.5 1 1.5 2 2.5 MHz 3 for DAB emissions in 0.77 1.75 0.97 L band (measurement Offset to center frequency bandwidth 4 kHz)

REFERENCES [1] Mayr, J.: DSR and DAB – Digital sound broadcasting today and tomorrow. News from other modules. This ensures high reli- In autumn 1995, the first European Rohde & Schwarz (1994) No. 145, pp 44 – 45 ability and a long service life for the DAB pilot project was launched in Ba- [2] Steen, R.: 250-W Solid-State DAB Transmitter whole amplifier. If the temperature at varia [4]. Since then Rohde & Schwarz SM225D1 – Terrestrial sound transmitter for the specially designed aluminium heat- transmitters have been demonstrating digital audio broadcasting. News from Rohde sink is too high, a temperature sensor their excellent quality and flexibility as & Schwarz (1995) No. 148, pp 29 – 31 in each of the two parallel amplifier stand-alones or as part of single-fre- [3] Heinemann, C.: COFDM Modulator MCM01 modules can switch off the carrier. A quency networks far beyond the bor- – Channel coding and modulation for digital audio broadcasting. News from Rohde & circulator at the output of each 100-W ders of Bavaria and Germany. Thanks Schwarz (1995) No. 148, pp 26 – 28 module protects the transistors in the to the company’s high level of expertise [4] Kalthoff, W.: Bavaria has started into DAB transmitter amplifier if there is excessive in the field of DAB, Rohde & Schwarz future. News from Rohde & Schwarz (1995) mismatch. has participated as a system and com- No. 149, pp 48 – 49

Practical applications

In July 1995 the participants in the T-DAB planning meeting in Wiesbaden finalized frequency and band allo- cations for terrestrial DAB. All DAB transmitters from Rohde & Schwarz Condensed data of 100/200-W Solid-State DAB Transmitter NL5010/5020 operate in the approved frequency Frequency range L band, 1452 to 1492 MHz ranges of 174 to 240 MHz and 1452 Input signal ETI version 4.0 to 1492 MHz. However, transmitters Output signal to ETS300401 are also available for the ranges 47 to RF output power 100 W (NL5010)/200 W (NL5020) 68 MHz and 87.5 to 108 MHz to Intermodulation suppression (f > ±977 kHz) >30 dB cover the whole frequency range used o Max. frequency error by DAB transmitters. Thanks to a four- without/with GPS unit 1 x 10–7/1 x 10–9 section output bandpass filter, the new Line voltage 3 x 400 V ±15% DAB solid-state transmitter has no prob- Power consumption 1.3/2.3 kW lems with the tolerance mask specified Cooling air intake approx. 7/13 m3/min for its frequency range (FIG 4). This Dimensions (W x H x D) 583 mm x 2026 mm x 1000 mm mask stipulates the maximum level for Weight approx. 275/310 kg emissions outside the frequency band Reader service card 152/08 occupied by the carriers.

26 News from Rohde & Schwarz Number 152 (1996/III) Articles

TV Transmitter Test System TS6140 High-grade test equipment is indispens- able for putting TV transmitters into service and maintaining them to ensure Guarantee of high signal quality that the highest transmission quality can always be obtained. In addition to in TV transmitter networks ITS systems for on-air monitoring of TV transmitters, Rohde & Schwarz now of- Does a TV transmitter comply with standard specifications? Is it possible to meas- fers TV Transmitter Test System TS6140 ure individual parameters during servicing? Can operating errors be avoided (FIG 1), based on Test System UCMF during servicing? These are questions which a TV network operator may ask. [1], for extensive, full-field transmission Rohde & Schwarz answers: no problem with TV Transmitter Test System TS6140, characteristic measurements off air. It the fourth generation of R&S test systems for television. is a reliable and easy to operate test system that has full-featured manual operation but also computer-aided test programs to simplify operation and prevent incorrect measurements.

Method of operation and design

TV Transmitter Test System TS6140 has all the features required for measuring the transmission characteristics of a TV transmitter to German standard specifications [2; 3] (FIG 2). In Signal Selector MFA703 the connections for the video and audio signals to and from the TV transmitter are made, the measuring instruments are configured and the RF and IF links between the test system and the transmitter are set up, depending on the measurement task. It also compen- sates for frequency response of the test cables. The TV transmitter is connected by means of cabling which can also be used for alternative DUTs (eg test demodulator or relay receiver). Inputs and outputs provided for video and audio signals on the front panel are used for testing individual units or PC boards, eg for repairs. These connections can also be reconfigured with the signal selector. All units are connected to Process Controller PSM7 via interfaces

FIG 1 Mobile version of TV Transmitter Test System TS6140 for comprehensive off-air vision and sound measurements Photo 42 486

News from Rohde & Schwarz Number 152 (1996/III) 27 Articles

ments. The operator selects the meas- CCVS Audio urements to be carried out from a table Generator Analyzer SFF UPD and specifies how the data are to be Signal Selector handled (storage, printing). After con- Video MFA703 TV Demod- Measurement ulator firmation of the settings, the measure- System VSA AMFS ments are run automatically in the selected order. The parameters (testpoint, Spectrum Power Analyzer Meter vision signal, etc) can also be config- FSEA20 NRVS ured separately. The automatic measurements handle all aspects of accep- CATV Head- Process end Equip- Controller tance testing for TV transmitters covered ment CT200 PSM7 in standard specifications. The comprehensive help function, specially designed for TS6140, can be called from any mode and so, in effect, is an online operating manual.

FIG 2 Block diagram of TV Transmitter Test dures. He selects the measurement item Special test facilities System TS6140 from a menu of ready-to-run measurements and performs it interactively TS6140 provides a number of new helped by the computer. The appropri- features that earlier generations of TV ate parameters are set via the graphics transmitter test systems did not have: user interface (FIG 3). Depending on (IEC/IEEE bus, serial interfaces) to the task, the computer can handle • Measurements can be made not on- control the test and output the results. device settings, signal path switching ly on the TV transmitter but also on The flexible system concept means that and choose a display mode for the test the test demodulator, relay receiver, customer-specific tasks can be accom- results. transposer and VF amplifier. modated. • Vision-Sound Modulator CT200-VS The results of each measurement are together with Sound-2 Coder-Mod- Characteristics and stored in a database on harddisk and ulator CT200-S2 and Upconverter applications can be exported to a floppy disk. Com- CT200-UP generates the required ments can be added to each measure- IF and RF test signals. TV Transmitter Test System TS6140 is ment and printed out at a later date. • Power Meter NRVS and Peak Power menu-controlled via the process control- Sensor NRVS-Z31 accurately and ler. The operating program was devel- TV Transmitter Test System TS6140 can rapidly measure the maximum avail- oped as an application under Microsoft also support acceptance tests or be able envelope power of periodically Windows; its graphics user interface used to document the condition of pulsed RF signals into 50 Ω and are provides a powerful user-friendly oper- equipment before and after repair work used for direct measurement of peak ating environment. TS6140 can, of performed with automatic measure- envelope power. Coupling and line course, be manually operated to per- losses are taken into account and form one-shot measurements. Signal- corrected. path switching is carried out from • Spectrum Analyzer FSEA20 [4] with Operating Panel MFA801 or via the its tracking generator provides the process controller’s graphics user inter- analyzer mode and can also per- face. The signal paths are displayed form frequency measurements. The clearly as symbols and block diagrams. frequency counter can be synchron- Connection is made immediately when ized to an external reference and the path is clicked with a mouse. The resolution set down to 0.1 Hz. The measuring instruments are set from the analyzer resolution bandwidth can front panel and test results are evaluat- be selected in 1, 2, 3, 5 steps from ed via the front-panel display of each 10 Hz to 10 MHz, the dynamic instrument. range is 95 dB. The RF and VF amplitude-frequency responses can be

The operator can also use computer- FIG 3 Operating program for one-shot meas- measured with FSEA20 and the aided measurement for service proce- urement mixer in MFA703.

28 News from Rohde & Schwarz Number 152 (1996/III) Articles

• Audio Analyzer UPD [5] measures REFERENCES dual-sound operating data. The [1] Deschler, W.: Television Test System UCMF [5] Kernchen, W.: Audio Analyzer UPD gener- switchable weighting filters allow – service for vision and sound. News ates and measures analog and digital au- from Rohde & Schwarz (1992) No. 138, dio signals. News from Rohde & Schwarz measurement of weighted and un- pp 18–20 (1992) No. 139, pp 13 –15 weighted S/N ratios to DIN/CCIR, [2] DBP/ARD: Standard Specifications No. [6] Bichlmaier, T.; Finkenzeller, R.: Video Meas- the tracking bandpass is used for 5/1.0, parts 1 and 2 urement System VSA – Four TV measuring measuring stereo and channel cross- [3] DBP/ARD: Standard Specifications No. instruments plus controller in one compact talk and the distortion meter for de- 5/2.1, January 1992 unit. News from Rohde & Schwarz (1995) No. 147, pp 18–21 termining total harmonic distortion [4] Wolf, J.: Spectrum Analyzer FSEA/FSEB – and the distortion for single harmon- New dimensions in spectral analysis. News from Rohde & Schwarz (1995) No. 148, ics. pp 4–8 • Video Measurement System VSA [6] is used to measure signals in the time domain and to determine group delay. The video and FFT analyzer of VSA simultaneously computes up Test parameters covered by TV Transmitter Test System TS6140 to 150 parameters from the input Measurements on vision transmitters transmitting power, vision-sound ratio, frequency, spurious emissions, level, signal. Analysis of the sin x/x signal amplitude-frequency response, frequency spectrum calculated with VF group delay, tilt, settling time, FFT gives the group delay curve. luminance nonlinearity, chrominance nonlinearity, difference-frequency distortion, phase deviation of vision Westdeutscher Rundfunk was the first carrier, intermodulation, unwanted modulation, intercarrier interference transmitter network operator to use the ratio modern TV Transmitter Test System Measurements on sound transmitters frequency deviation (levelling), TS6140. It has been in operation for differential deviation, amplitude- several months at three sites and this frequency response, preemphasis, stereo and channel crosstalk, THD system will soon be installed in six and difference-frequency distortion, other transmitter stations and a test unwanted FM modulation, polarity laboratory. Reader service card 152/09 Walter Deschler; Gerhard Strauss

EMC system solutions: We watch the rule Reference

This was the motto of a comprehensive PR cam- Rohde & Schwarz is the pacemaker and world- upon support and products from Rohde & Schwarz. paign Siemens Matsushita Components started market leader in EMC compliance test engineer- Rohde & Schwarz offers test receivers, spectrum an- in the leadup to 1 January 1996, the date as of ing. Participation in international standardization alyzers, signal generators, amplifiers and antennas which electronic products irrevocably had to bodies ensures that hardware and software are al- for measuring interference and electromagnetic sus- comply with German EMC legislation. The range ways in conformance with the relevant standards. ceptibility of machines, vehicles and the like. Sö of EMC test equipment, accessories and software The company’s com- packages has become larger, and small- and petence and efficiency medium-sized companies now have the possibil- is also underscored by ity of performing at least some EMC measure- the fact that Europe’s ments using their own personnel and equipment. largest EMC test cen- The focus in one of the ads by which Siemens ter in Greding was de- Matsushita Components presented its EMC prod- signed, equipped and uct line is an EMC test assembly from Rohde & handed over turnkey Schwarz (photo). This assembly comprises a by Rohde & Schwarz test antenna, a PC with test software (left), a test and that practically all receiver (center) as well as a signal generator, renowned firms in the an artificial mains network and a power amplifier automobile and elec- (right, from bottom). tronics industry rely

News from Rohde & Schwarz Number 152 (1996/III) 29 Articles

VHF-UHF Direction Finder DDF190 nas. When used for stationary applications, the antennas can be located up to 95 m from the DF unit using the stan- Digital direction finding dard cable sets. For cables longer than 40 m an additional power supply unit from 20 to 3000 MHz is provided. to ITU guidelines Direction Finder DDF190 operates as a correlative interferometer and can DDF190, the youngest member of the new digital DF family, has now been handle all types of modulation. The launched on the market. This compact DF add-on for VHF-UHF receivers is direction finding procedure makes use available at an extremely favourable price. It operates on the correlation of digital signal processing. The phase principle and is mainly used for locating sources of interference and unauthor- differences between the antenna volt- ized emitters. ages generated by the signal received by the antennas are compared with reference values and then checked for Digital signal processing coupled with maximum correlation. The advantage innovative RF technology has set new of this DF method is that, because standards in many fields and direction antenna elements do not need to be finding is one of them. DDF190, a fully grouped into subarrays, wide-aperture remote-controlled DF add-on for com- DF antennas can be used covering mercial receivers with an unregulated large frequency ranges with a minimum 10.7-Hz or 21.4-MHz IF output follows number of antenna elements. on from the fast Scanning Direction Finder DDF0xS [1] and Monitoring Operation Direction Finder DDF0xM [2]. ESMC and ESN from the Rohde & Schwarz DF Unit EBD 190 is operated using a receiver program are ideal for use clearly laid-out front panel keypad with DDF190, which is a very cost- and a large LCD (FIG 3). All functions effective way of adding an extremely required during operation are under di- broadband direction finder to high- rect key control. The receiver is operat- quality measuring and monitoring ed separately, but the interfaces for an- systems. tenna range selection are supported. Since direction finding is performed by DDF190’s design meets the recommen- sequential scanning of the DF elements, dations in the ITU Spectrum Monitoring and only one receiver is used, switch- Handbook [3]. The wide frequency ing noise is produced in the AF signal range from 20 to 3000 MHz and high of the receiver. To eliminate this noise system accuracy make DDF190 ideal when aural monitoring is being per- for civil radiomonitoring tasks. Thanks formed, scanning and so direction find- to its compact design it can be used for ing may be switched off. Selectable av- mobile as well as stationary applica- eraging times (0.1 to 5 s) and matched tions (FIG 1). Since DDF190 is also filtering in DDF 190 (1 to 100 kHz) con- system-compatible, it can be used as a siderably improve bearing accuracy – stand-alone unit or be networked for particularly in the case of noisy signals a variety of system applications. The or signals with interference. whole frequency range is covered with just two antennas. Since only one co- Three operating modes and two dis- axial cable and control cable are re- play modes optimize direction finding quired to connect up DF Unit EBD190, for various applications. FIG 1 DF and monitoring vehicle with VHF-UHF installation is simple and low-cost. The Direction Finder DDF190. With its upper fre- direction finder can, of course, be In normal mode the DF process is con- quency of 3 GHz, DDF190 can also detect powered from a battery or the AC sup- trolled by a selectable squelch thresh- sources of interference affecting new radio services (eg GSM, PCN, PCS, WLL and GPS). ply. In both cases the DF unit provides old which is compared with the current- Photo 42 572 the supply voltage for the active anten- ly received, relative IF level. It is best to

30 News from Rohde & Schwarz Number 152 (1996/III) Articles

with each DF value. For stationary applications, a compass with north adjustment is used as a reference and the vehicle axis for mobile applications. The latter is crucial when the vehicle is being used for homing. In this case a compass is also used to continuously indicate where north is with respect to the vehicle. Vector direction finding with QDM as used in air traffic control can also be selected.

In each of these modes DF values can also be displayed as a histogram in addition to the display mode already referred to. This is very useful for analyzing communication networks: all DF values obtained since this display mode was activated are displayed as rays, the length of each ray being a measure of the frequency of occurrence of the bearing angle it represents. Results can also be displayed and printed out as lists. Postprocessing functions like smoothing, determination of local max- ima and sorting support histogram analysis.

FIG 2 DDF190 upgrades VHF-UHF receivers to memory is not cleared if the signal is On power up of the direction finder, the top-end DF system – with accuracy and sensitivity below the threshold. Integration over system environment (antennas, class above 1 GHz unrivalled by any other compact unit. Photo 42 571/1 many pulses is therefore possible. of receiver, compass) is automatically determined. A realtime clock outputs a The DF display comprises a three-digit time marker for each bearing taken. number and a radius for indicating This facilitates bearing/emitter assign- direction. The DF quality, derived from ment in networked DF and radioloca- use this mode for monitoring radio the correlation function, is displayed tion systems. networks or simplex communication. Bearings of short-duration signals (minimum 50 ms) can also be taken. As the selected averaging is cancelled at the end of a signal, the bearing display follows the changing directions of incidence without any delay.

In continuous mode direction finding is performed continuously. With sliding averaging, the display is updated every 0.5 s. This means that direction finding can be performed on weak signals or signals with a very large bandwidth.

FIG 3 The gate mode is used for bearings on Front view of keyed transmitters as the squelch thresh- DF Unit EBD190 old is also activated but the averaging Photo 42 473

News from Rohde & Schwarz Number 152 (1996/III) 31 Articles

which DDF190 can be directly integrated. Radiomonitoring System TS9965 [4] provides fully automatic monitoring, measurements and analysis to CCIR and ITU recommendations. In the DF measurement mode, results from several DF stations can be handled and marked on a digitized map. Within this system, DDF190 may be connected to receivers with IEC/IEEE-bus control in unmanned stations. Channel and frequency scans are also supported. The Radiolocation System RAMON-locate [5] was designed to accommodate the DDF190/ESMC combination. FIG 4 Franz Demmel; Raimund Wille Antennas ADD190 (top) and ADD071 on common mast Photo 42 477/1

Antennas REFERENCES The range 20 to 1300 MHz is covered sequences for receiver control are [1] Bott, R.: Digital Direction Finder DDF – Mod- by Antenna ADD190. Its small diame- passed on by the DF unit. Compact ern scanning direction finding from 0.5 to 1300 MHz. News from Rohde & Schwarz ter of only 1 m and the uncriticality of commands and configurable message (1994) No. 146, pp 26–28 polarization make the antenna ideal for formats reduce the required commu- [2] Demmel, F.; Unselt, U.; Schmengler, E.: Digi- mobile applications although it also has nication capacity to a minimum. Two tal Monitoring Direction Finders DDF0xM – considerable advantages in stationary modes using a minimum number of State-of-the-art monitoring direction finding use. Thanks to its small size, it is unob- messages are provided in addition to from HF to UHF. News from Rohde & Schwarz (1996) No. 150, pp 22–24 trusive, protected as standard against the three operating modes: timed single [3] International Telecommunication Union: direct lightning strikes and can with- and repetitive DF. An external control Spectrum Monitoring Handbook (1995) stand wind speeds of 200 km/h. input is provided for a radio modem; [4] Pfitzner, J.: Radiomonitoring System TS9965 this does not affect direction finding – Complete coverage up to 18 GHz. Antenna ADD071 is provided for the in any way (internal transmitter sup- News from Rohde & Schwarz (1994) No. UHF range 1.3 to 3 GHz. Designed pression). 146, pp 22–25 as a circular array of dipoles in front [5] Ehrichs, R.; Holland, C.; Klenner, G.: Radio- monitoring System RAMON – Customized of a reflector, ADD071 may be fitted To create larger systems with DF sta- radiomonitoring from VLF through SHF. on the same mast as ADD190 (FIG 4). tions at any location, Rohde & Schwarz News from Rohde & Schwarz (1996) This combination is already available offers comprehensive solutions into No. 151, pp 19–21 as standard.

An electronic compass add-on may be fixed to the antennas for automatic Condensed data of VHF-UHF Direction Finder DDF190 direction finding referred to north. Frequency range VHF/UHF (20 to 1300 MHz) (depending on receiver and DF antenna) UHF (1.3 to 3 GHz) System compatibility DF error 2° rms (30 to 80 MHz) 1° rms (80 to 1300 MHz) 2° rms (1.3 to 2.7 GHz) DF Unit EBD190 provides remote con- DF sensitivity frequency-dependent trol via a serial RS-232-C interface. VHF/UHF 1.5 to 10 µV/m Remote control (virtual control panel) UHF 3 to 10 µV/m is identical to front-panel operation. Minimum signal duration approx. 50 ms The DF unit also provides an RS-422/ Bandwidths 1/2.5/8/25/100 kHz RS-485 and a TTL parallel interface Reader service card 152/10 for the connected receiver. Character

32 News from Rohde & Schwarz Number 152 (1996/III) Application notes

EMC measurements up to 40 GHz with Microwave Signal Generator SMP

Apart from an RF signal of high spectral purity and precisely adjustable output power, signal generators for EMC measurements require top-quality AM and pulse modulation, spike-free frequency and level sweeps and last but not least a mature operating concept permitting automatic measurement sequences to be performed with or without an external controller. The microwave generators from the SMP family set the standards – as do all other signal generators from Rohde & Schwarz. Four models and a comprehensive range of options are available from which the user may choose the equipment he needs – tailored to his specific requirements – at an excellent and unrivalled price/performance ratio [1 to 3].

The term electromagnetic compatibility FIG 1 Signal Generator SMP and GTEM (giga- As said already, mature standards and (EMC) is very apt: if people are com- hertz transverse electromagnetic) cell – an up-to- test specifications are currently avail- date combination for susceptibility measurements patible they can work together easily Photo 42 574 able for civil and military applications and effectively without anyone disturb- in the range up to 1 GHz. Military ing anyone else, and the same applies standards still apply to higher fre- to electrical devices. Certain ground tions, where sensitive receivers, power- quencies, although lately more and rules must be observed in any partner- ful transmitters and noisy engines have more civil applications are transferring ship and this is why EMC standards always had to operate in close proxim- to this range. Examples can be found in and suitable measuring instruments ity without interfering with one another. satellite communications as well as in were developed at a very early stage. Compatibility principles were, there- automobile and aeronautical engi- However, the frequency range did not fore, defined and appropriate test neering. It can be assumed, therefore, go beyond 1 GHz as this was all that equipment developed. Adapted to that standards for EMC tests will be was required for all the main activities present-day requirements, these princi- extended to 40 GHz in the near future. of modern radiocommunication. The ples are now the basis of current nation- New top-class technology at an afford- range beyond 1 GHz was generally al and international EMC regulations. able price will obviously be required reserved for military and scientific applications.

FIG 2 Measurement The need for EMC testing has always of immunity to radiated been appreciated by forward-looking Artificial-mains interference from 1 to manufacturers of top-quality electronic network 40 GHz using Signal Generator SMP (to devices and systems. The end of the DUT E field sensor MIL-STD-462D). Signal transition period for the CE mark at the Generator SMP04 beginning of this year would not have Boundaries of test setup (10 MHz to 40 GHz) been a reason to implement any major Antenna is used as stimulator, changes as EMC awareness was al- EMI Test Receiver ESMI Shielded chamber with Harmonic Mixer ready considered good practice. The FS-Z40 for display Signal EMC test equipment used today derives Power Simulation Field-strength purposes and field- Generator amplifier and display meter from equipment for military applica- SMP04 strength measurements.

News from Rohde & Schwarz Number 152 (1996/III) 33 Application notes

Selection of currently valid military and civil EMC standards for the microwave range

Standard Designation Description Microwave range Application

MIL-STD-461D/462D Radiated Emissions, Measurement of harmonics 1 to 40 GHz Military (USA) RES103 Antenna Spurious and and spurious emissions Harmonic Outputs from antennas MIL-STD-461D/462D Radiated Susceptibility, Measurement of immunity to 1 to 40 GHz Military (USA) RES103 Electric Fields radiated RFI (electric field) DEF STAN 59-41 Radiated Susceptibility Measurement of immunity 0.79 to 18 GHz Military (UK) (PART 3), DRS03 to radiated RFI VG 95 370/VG 95 373, Messverfahren für Störsicherheits- Measurement of immunity 1 to 40 GHz Military (Germany) Teil 13, abstände gegenüber systemeigenen to radiated RFI Messverfahren SF 04 G Feldstärken SAEJ1113 Part 21 Semi-anechoic Chamber Measurement of immunity 0.03 to 18 GHz Vehicle test (USA) to radiated RFI ISO 11451-2/ Road vehicles – Electrical disturbances Measurement of immunity 0.2 to 18 GHz Vehicle test ISO 11452-2 by narrowband radiated electromagnetic to radiated RFI (international) energy – vehicle test methods – Part 2: Off-vehicle radiation sources EN 50083-2 Cabled distribution systems for television Measurement of radiated 1 to 25 GHz Telecommunications, and sound signals – Part 2: interference TV and sound Electromagnetic compatibility (substitution method) broadcasting (Europe) for equipment

and is already available in the form of bandwidth connected to an antenna fier down-stream or even the DUT generator family SMP (FIG 1) from emitting the signals for irradiating the and will certainly cause measurement Rohde & Schwarz with models from DUT (FIG 2). Depending on the require- errors. 10 MHz/2 GHz to 20, 27 and ments, the DUT’s functions should not 40 GHz. The table in the blue box be impaired at all or only within certain Another main application of micro- gives a selection of current military defined limits. In particular, there may wave signal generators is the calibra- and civil EMC standards covering 1 to be DUT resonances at the high-frequen- tion of test setups, as shown in FIG 3. 40 GHz. cy end of the microwave band: small Prior to the actual measurement, the slits in the housing or short line struc- signal generator is used to calibrate A glance at the standards shows the tures in circuits or on PCBs may act as the level display of the test receiver. main fields of application for micro- high-Q resonators and cause total fail- Obviously, the accuracy and stability of wave signal generators. First, there are ure in an extremely narrow frequency the generator level have to meet strin- measurements of immunity to radi- range. Thanks to SMP’s digital sweep gent requirements. Thanks to an over- ated interference – also known as sus- such resonance points can be rapidly designed ALC system and careful instru- ceptibility measurements. In this case and reliably detected, the smallest set- ment calibration in the factory, this is no the signal generator usually drives a table increment being 0.1 Hz. The ex- problem for generators from the SMP power amplifier with an appropriate cellent frequency stability also ensures family. The test receiver used in test that measurements can be reproduced. setups like that shown in FIG 3 can Any DUT malfunction can be found and also be calibrated by applying the demonstrated at a later date. Another generator signal to the receiver via an important advantage of the SMP sweep antenna and not via a cable [2]. This FIG 3 Measurement of radiated harmonics and spurious from 1 to 40 GHz to MIL-STD-462D using is that there are no level spikes. Level means that the transfer characteristics Signal Generator SMP and EMI Test Receiver ESMI spikes may destroy any power ampli- of the receiving antenna are also taken into account.

Signal path for measurement Normally, frequency drifts in RF cables,

EMI Test power amplifiers and the antenna of DUT Bandstop Bandpass Receiver the test setup cause considerable level (transmitter) or filter ESMI + highpass filter Harmonic Mixer errors. This cannot be avoided in spite FS-Z40 Transmitting Receiving antenna antenna Signal path for system check of the excellent level accuracy of SMP

(typical error 0.1 dB). Fortunately, SMP Power Signal does have a number of functions for monitor Generator SMP04 frequency response correction:

34 News from Rohde & Schwarz Number 152 (1996/III) Application notes

• user correction for a user-defined RF grammers of automatic test systems pre- REFERENCES frequency response, fer direct frequency response correction [1] Kraemer, W.: Signal Generator SMP – The • memory sequence, a programmable via IEC/IEEE bus using the controller. microwave generator for stringent requirements. News from Rohde & Schwarz (1994) sequence of complete front-panel In this case, level control is performed No. 144, pp 11 – 14 setups, by SMP’s ALC, giving resolution of [2] Kraemer, W.: Signal Generators SMP03 and • list mode, a programmable se- 0.01 dB. The actual value is deter- SMP04 – Powerful microwave generators up quence of up to 2003 frequen- mined by means of a power meter with to 40 GHz. News from Rohde & Schwarz cy/level pairs, directional coupler at the antenna input (1995) No. 147, pp 10 – 13 • and, last but not least, external level or via a field-strength sensor near the [3] Kraemer, W.: Microwave Generator SMP – top-class performance to customer’s benefit. control using an external power me- DUT. News from Rohde & Schwarz (1995) No. ter [4]. 151, pp 58 – 59 The above examples clearly show that [4] Kraemer, W.: External, precision level control When SMP is operated manually, ie SMP, a powerful, future-oriented and for microwave Signal Generator SMP. News without an external controller, it is best favourably priced instrument from a from Rohde & Schwarz (1994) No. 144, p 14 to use the user correction function to manufacturer with decades of experi- correct the overall frequency response. ence in all fields of EMC measure- If a Power Meter NRVS or NRVD is ments, is the right solution to any available, the required correction EMC measurement problem between values can be determined automati- 10 MHz and 40 GHz. cally by means of a keystroke. Pro- Wilhelm Kraemer Reader service card 152/11

Optimizing wireless local loop systems Test hint

DECT is not only used for classic applications such as algorithms but also geographical conditions have to detected. Thus the operator can draw conclusions domestic cordless phones, but is also considered a be utilized optimally (eg by means of directional about the strong and weak points of channel selec- solution for making the last step in the implemen- antennas at the transmitter and receiver end). tion algorithms. tation of new telecommunications networks. This application called WLL (wireless local loop) is at In addition, the optional channel occupancy soft- present being tested in various field trials. Other ware informs the user about the receive levels than with GSM, DECT frequencies are not allocated measured on all DECT channels (RSSI value) and to a specific operator but can be used by every type- about the origin of the signals received. The signals approved DECT application. Consequently, the might originate from coordinated or uncoordinated DECT frequency band has to be shared with DECT DECT units and non-identifiable interference sources units working in an uncoordinated manner. The (FIG). The physical parameters of the DECT signals DECT standard allows for this by defining dynamic and the identities exchanged are also indicated, so channel selection (DCS) and associated handover the signals can very easily be allocated to sources procedures that switch over to other channels in case inside or outside the network. Moreover, the option of interference or sliding collisions to ensure DECT Protocol Tester TS1220 (see News from allows antenna positions to be optimized using the interruption-free communication. Rohde & Schwarz No. 148) supports the operators RSSI values which are referred to the identities dis- of DECT WLL networks both in the assessment of played. TS1220 can either be installed in a vehicle The algorithm for dynamic channel selection has not DCS algorithms and the optimal positioning of for mobile use and operated with its own height- been defined exactly. The solutions are manu- antennas. In the monitoring mode the system syn- adjustable antenna. Or it can be connected direct to facturer-specific and not disclosed to the public. The chronizes itself to a user-defined DECT fixed part the antennas used in the network. traffic capacity specified for DECT, which is high in and logs all data packets exchanged with portable Marcus Gloger; Peter Riedel comparison with GSM, is based on theoretical parts via the air interface without intervening with considerations assuming an optimum DCS the DECT network. On the basis of the data collect- algorithm. To attain the specified value under real- ed, failed or successful handover and communica- Reader service card 152/12 for further infor- world conditions, not only well-proven DCS tion attempts as well as occupied channels can be mation on TS1220

News from Rohde & Schwarz Number 152 (1996/III) 35 Application notes

Measurements on hearing aids with Audio Analyzers UPD and UPL

starting the program, the user can select the standard according to which measurements are to be performed, ie ANSI S3.22 or IEC 118. Test settings are stored separately for each standard and are recalled each time the program is started.

The measurement menu of the application program offers the following choice of settings and test functions: FIG 1 Audio Analyzer UPD – ideal for standard CONFIG, DUT, FRQ-RESP, IN-OUT, tests on hearing aids Photo 41 956 DIST, NOISE, ATTACK, CALIB.

Prior to initial measurement, the micro- The ear is an extremely sensitive organ. bution and crest factor will be generat- phones and test chamber must be cali- If healthy, it is capable of processing ed and the correlation between the out- brated using the CALIB menu item. The sounds with an extremely wide put signal of the hearing aid and the in- calibration data of the microphones dynamic range. Nevertheless, it can put signal determined. Manufacturers of and the frequency response of the test easily be damaged by longterm ex- hearing aids, especially those supplying chamber are stored and taken into posure to, say, industrial noise or ex- the US market, will shortly be obliged to account automatically each time the cessive noise levels in discos or from test their products to these standards. program is restarted. After each cali- walkmen. As the effect on hearing is With its Audio Analyzer UPD [1] and bration, the microphone data are often only noticed later on, there is an High-Speed Option UPD-B3, Rohde & added to a file named MICRO.HST. increasing number of young people Schwarz can already provide the test This file can be analyzed to verify the with hearing defects that have to be and measuring equipment required. stability of the microphone data. corrected with a hearing aid. Special application programs for The parameters for the test steps are Hearing defects are caused by a wide Audio Analyzers UPD and UPL [2] defined using the CONFIG menu item, range of impairments of the hearing ca- make it possible to perform measure- for instance scaling for frequency pacity, for example by frequency- ments on hearing aids to IEC 118 and response measurements, broadband or dependent sensitivity losses in specific ANSI S3.22. Measurements are per- selective measurements, etc. The data frequency ranges or by a shifting of the formed in an acoustic test chamber, are permanently stored and used in all complete sensitivity curve. Modern which may be an anechoic room or a subsequent measurements. hearing aids must, therefore, be ca- small test chamber with appropriate pable of compensating for a variety of damping. Commercial test micro- defects, and a precise determination of phones can be used, and the loud- their electroacoustic characteristics is speaker of the test chamber can be essential. driven directly by UPD (FIG 1) or UPL if efficiency is sufficiently high. A coupler There are several national and inter- to IEC 126 or an ear simulator to IEC national standards (eg IEC 118 Parts 0 711 can be used for connecting the to 12 and ANSI S3.22) that define microphone to the hearing aid. No measurements on hearing aids using further equipment is required except for sinusoidal tones. Further standards (eg a printer if the user wishes to log results. ANSI S3.42) defining measurements on hearing aids using a broadband The application program runs under FIG 2 Frequency response of sound pressure noise signal are in preparation. For the the UPD or UPL universal sequence con- saturation level of hearing aid at maximum gain, latter type of measurements, a signal troller and is operated via softkeys or and output sound level with input sound level of with precisely defined frequency distri- function keys on a keyboard. After 60 dB as reference

36 News from Rohde & Schwarz Number 152 (1996/III) Application notes

The DUT data are entered using the ear as far as possible. Only the Precise measurement of the electro- DUT menu item. These data are printed acoustic signal should be amplified, the acoustic characteristics of a hearing out with the result graphics. inherent noise of the hearing aid being aid is essential if the development, kept as low as possible. The NOISE production and quality management of One of the most important character- measurement is made to determine the the product are to be improved. This istics of a hearing aid is its frequency acoustic noise pressure output level of information is also vital for the case response: FRQ-RESP menu item. To the hearing aid with no input. From notes of patients whose hearing aids measure the response, the hearing aid these data and the gain of the hearing have been adapted to compensate for is first of all set to maximum gain and aid, the equivalent input noise pressure a specific hearing problem. Like other the output sound level measured at level can be calculated. Naturally, electromedical equipment, hearing 90 dB sound pressure. This gives the external noise must be sufficiently aids must undergo type testing before sound pressure saturation curve. Next, they can be sold. In Germany, such the reference gain of the hearing aid is tests are performed by the Physikalisch- set and the frequency response meas- Technische Bundesanstalt (Federal ured at 60 dB or 50 dB sound pressure German Bureau of Standards) in level, depending on the type of hearing Brunswick. This federal test agency aid. The resulting curve is displayed in uses Audio Analyzer UPD and the the same diagram as the sound pres- special application program to carry sure saturation curve (FIG 2). On com- out type-approval tests on hearing aids. pletion of the measurement, the user Every hearing aid manufacturer that can rescale the Y axis as desired, dis- uses Audio Analyzer UPD or UPL can play the frequency response curve as be sure that he will meet all relevant the acoustic gain curve and, in this dis- technical requirements for type-approv- play mode, generate further curves, for FIG 3 Output sound level vs input sound level of al tests. instance to determine the effect of fre- hearing aid at 500, 1000, 1600, 2500 and Tilman Betz quency response controls by means of 4000 Hz a set of curves. Results can be output using a HPGL printer, so providing documentation that meets the standards for attenuated by the test chamber if this official product approval. measurement is to produce useful results. The acoustic transfer characteristic – IN-OUT menu item – of a hearing aid is A characteristic of hearing aids that is needed to correct sensitivity losses of particularly difficult to describe is the the ear as a function of volume. How AGC response time. State-of-the-art the transfer characteristic varies with hearing aids often have multistage frequency can be determined by control circuits with different time performing measurements to obtain up constants. For example, individual gain to five traces (sound pressure level, control or compression is applied to gain or compression ratio) at selectable syllables, so the response time must be frequencies (FIG 3). milliseconds. The ATTACK menu item is used to perform automatic measure- A hearing aid should output the am- ments on the attack and release times of plified signal with as little distortion as hearing aids with AGC. The test possible if the original sound is to be conditions can be user-defined. Attack reproduced as faithfully as possible. and release curves are displayed and REFERENCES Using the DIST menu item, distortion evaluated by the program, and the [1] Kernchen, W.: Audio Analyzer UPD generates of the acoustic signal is measured at results output as numerical values. For and measures analog and digital audio signals. News from Rohde & Schwarz (1992) 70 dB sound pressure level over the the first time ever, a function has been No. 139, pp 13 – 15 whole frequency range. The D2 and implemented that provides an easy [2] Kernchen, W.: Audio Analyzer UPL – audio D3 distortion products are determined way of making measurements on and analysis today and tomorrow. News from and displayed as curves in a diagram. documenting the complex control Rohde & Schwarz (1996) No. 151, pp 4 – 7 response of hearing aids from fractions The gain of the hearing aid is needed of milliseconds up to several seconds in to restore the original sensitivity of the one go. Reader service card 152/13

News from Rohde & Schwarz Number 152 (1996/III) 37 Application notes

Quality testing of mobile phones using multitone audio analysis of Digital Radiocommunication Tester CMD

new measurement mode, CMD (FIG 1) generates up to 14 user-selectable frequencies in the range 50 Hz to 8 kHz with individually adjustable levels (can also be switched off). After the multi- frequency signal has passed through the DUT, CMD performs narrowband voltage measurements at these frequencies.

Measurements

Fast frequency response measurement (FIG 2): the user selects 14 points on the frequency response curve and sets each frequency to the same level. Measuring the output levels of the DUT at these points gives the frequency response of the DUT. If there are frequencies which have passed through the DUT and are far below the possible measurement limits, the measurement range for these particular frequencies can be extended by increasing the level on the generator side. Since all frequencies are measured simultane- FIG 1 To handle more stringent quality require- Using the right measurement technolo- ously, the frequency response measurements for GSM and DECT mobile stations, Digital Radiocommunication Tester CMD from Rohde & gy has a positive effect on quality. From ment is fast in spite of the narrow Schwarz was upgraded with powerful AF meas- the outset, Rohde & Schwarz has de- measurement bandwidth (approx. 2 s urement functions. Photo 40 944/1 signed its GSM and DECT production at 1 Hz). This measurement is a good testers to guarantee quality at the RF choice for noisy production environ- interface [1; 2]. In the meantime, this ments as most of the external noise is has come to be thought of as a stan- excluded thanks to the narrow measure- dard basic function. The situation is ment bandwidth. different as far as the AF interface of the mobile is concerned. Within the accept- True harmonic distortion measurement: Europe is not the only place where able quality range, quality differences the distortion measurement performed digital GSM and DECT networks have in the audio signal can be clearly dis- up to now was in fact a SINAD meas- flourished. Variations of these networks cerned by the user and this may influ- urement, ie the total signal is referenced are taking hold all over the world, but ence his decision to buy. to a signal from which the fundamen- the market is by no means saturated. tal has been removed. With multitone Manufacturers of mobile phones still For this reason, Rohde & Schwarz has audio analysis individual harmonics have to woo the customer to win orders. considerably upgraded the AF meas- can be singled out. The fundamental All manufacturers are able to supply urement capabilities of its GSM/DCS frequency at a certain level is set on the the basic functions required for mobile 1800/DCS 1900 and DECT radio- signal generator. Then up to 13 har- operation and so customers now tend communication testers. Multitone audio monics are chosen with the signal gen- to go for features that can be assessed analysis has been added to functions erator switched off. On the output side, directly rather than the provision of such as AF generator, AF meter with narrowband measurements on all the basic features. Design and quality are rms and peak value meter, distortion frequencies provide information about features that can clinch a purchase. meter and frequency counter. In the the whole harmonic spectrum.

38 News from Rohde & Schwarz Number 152 (1996/III) Application notes

FIG 2 AF frequency response. Results from multitone audio analysis are FIG 3 AF intermodulation measurement. Two larger bars represent test always displayed as bargraphs. Bars represent points selected on DUT’s AF tones, smaller ones at right and left unwanted intermodulation products meas- frequency response. ured by CMD at high speed over wide dynamic range.

Intermodulation measurement (FIG 3): Operating modes: in the single-shot a single go/nogo outcome can be like distortion measurement, this meas- mode, the generator can be started obtained from every group of 14 results urement too is used to check the linear- before the analyzer to allow the DUT – in other words, a single, accurate ity of the DUT. Two test tones instead of to settle completely before the measure- conclusive result can be obtained from one are used in this case, however. The ment is started. Normally the continu- a complex measurement. intermodulation products occur at pre- ous measurement mode is chosen for cisely predictable frequencies which manual operation, results being up- Result display: the great variety of are a function of the two test tones. Con- dated every second. If the operator sus- display and scaling modes – tailored sequently, a level is assigned to two of pects that there is an out-of-tolerance to specific measurement tasks – makes the frequencies and the others are set to condition, continuous measurement reading of results easy and simplifies the expected intermodulation frequen- can be stopped to examine the outlier their interpretation. Any signal gener- cies with no generator signal present. more closely. ator level may be used as a reference for the measurements or an indepen- Aliasing products: prior to transmitting Analysis using tolerances: as with dent reference value can be defined. analog voice signals in a range from any other CMD result, tolerances may As appropriate, log or linear scales 300 Hz to 3.3 kHz on the digital be set for the results obtained from may be chosen on CMD. network, the signals are sampled at a multitone audio analysis on a go/nogo Thomas Maucksch rate of 8 kHz. Frequency components basis. With the aid of this function, above 4 kHz must not reach the sam- pler as otherwise unwanted aliasing products would be produced. Knowing the test frequency and the sampling fre- ADPCM quency, the aliasing frequency can be ROHDE & SCHWARZ REFERENCES determined precisely. The level is then [1] Maucksch, T.: Digital Radiocommunication measured at these points. CMD Tester CMD60 – A favourably priced compact test set for series production of DECT mobiles. News from Rohde & Schwarz Control and operation (1995) No. 149, pp 13–15 Mod. AF voltmeter RF [2] Vohrer, M.: Multimode Radiocommunication Signal paths (FIG 4): CMD’s AF inter- gen. Tester CMD for GSM, PCN, PCS and DECT face with its new multitone analysis mobiles. News from Rohde & Schwarz DUT facilities and the “old” AF test functions (1996) No. 150, pp 53– 54 with generator and analyzer can be connected to the front-panel connectors or to CMD’s ADPCM interface for DECT applications. If CMD is equipped with FIG 4 Setup for measuring frequency response, distortion, intermodulation and aliasing in micro- a Speech Encoder/Decoder CMD-B5 phone path of DUT (here DECT portable part). for GSM, the AF interface may be Similar setup is used for measurements in loud- internally switched to this option. speaker path. Reader service card 152/14

News from Rohde & Schwarz Number 152 (1996/III) 39 Application notes

Tailor-made applications in industrial automation with factory user port for Controller PSM

FIG 1 Industrial Controller PSM is ideal for auto- A microcontroller controls all these func- Applications matic test facilities. Photo 41 488/1 tions. It is connected to the ISA bus in PSM, from where it can be conveniently Since Industrial Controller PSM was operated via the FUP software interface launched on the market approx- using the following languages: imately two years ago, Rohde & Automatic testing often requires only • R&S BASIC, Schwarz has published more than relatively simple functions for setting • Microsoft VisualBASIC for DOS, ten application notes, which can be and evaluating a DUT, eg a mobile • Microsoft VisualBASIC for Windows, obtained by all users from their R&S phone. For these purposes Industrial • Microsoft BASIC PDS 7.0, representative. Relevant applications Controller PSM (FIG 1) [1; 2] is • Microsoft QuickBASIC, for the FUP are DC measurements equipped to standard with the factory • Microsoft C for DOS, (V, I, R), AC line monitoring, battery user port (FUP), a universal interface. • Microsoft C for Windows, testing and remote control of satellite This means that a multitude of applica- • Borland Pascal 7.0, antennas. The first three applications tions can be implemented without any • Microsoft Pascal 4.0. demonstrate the powerful language additional hardware. The supplied soft- interface of the FUP, whereas the ware library considerably reduces the fourth makes use of its complete range time required to become familiar with FIG 2 Functions of factory user port for Industrial of functions and involves writing firm- the FUP and its operation. Controller PSM ware.

Function blocks 10-bit A/D converter 0 to 5 V Power supply

The factory user port provides the fol- D 12.00 5.00 A lowing functions for use with external +12 V -12 V GND +5 V equipment (FIG 2): • 10-bit A/D converter, four channels, Programmable pulse signal Relays 0 to 5 V, • eight digital inputs and outputs, 0% 100% • pulse width modulator which can also be used as an analog output, • optocoupler input, Optocoupler • optocoupler output,

• two relays, each with a changeover 8-bit digital I/O FUP connector switch, at rear of unit • supply voltages for external circuits.

40 News from Rohde & Schwarz Number 152 (1996/III) Application notes

DC current and voltage measurements This application also provides an intro- different pulse widths representing a 1 In many cases this simple application duction to programming the FUP using or a 0. As these pulses have to be very (Application Notes 1CMAN19 and VisualBASIC and shows you how short (64 or 86 µs), an independent AN20) makes an external IEC/IEEE- to write a Windows program too. The microcontroller such as the one provid- bus multimeter superfluous; it demon- battery under test is first discharged ed in the FUP is an ideal pulse source. strates DC voltage or DC current meas- until a preset minimum voltage is In this case, software which has been urements. Sampling every 100 ms (in reached. It is then recharged until either specially designed for this task is the VisualBASIC example) means that slowly varying quantities can also be measured. There are four measurement ranges: 10 V, 100 V, 1 A and 10 A. Each measurement range is assigned to one of the four A/D converter inputs via a matching circuit. The minus pole of the signal to be measured is connected to PSM’s ground. Application Note AN19 describes control under VisualBASIC, whereas AN20 deals with control under Rohde & Schwarz BASIC. R&S BASIC has a steep learning curve, as the interpreter immediately executes any command that is entered. FIG 3 AC line monitoring Screen display for battery testing This application example (Application application Note 1CMAN22) describes how to monitor the AC line. The optional DC Supply (PSM-B3) must be fitted to PSM if you want to measure power supply drops or failures. This option can also be modified to give an uninterruptible a maximum voltage or a maximum loaded into the FUP microcontroller and power supply. AC line monitoring temperature is exceeded. The battery is started. A software library has been is performed under VisualBASIC. The now fully charged and its capacitance supplied to make it easy to send data to rectified AC voltage which has been can be checked in another discharge the microcontroller and so position the tapped via a transformer is measured cycle. The VisualBASIC program sup- antenna. periodically. Supply failures and their plied shows two graphic windows with Joachim Stegmaier durations are recorded. The AC curves describing the battery voltage voltage is also monitored so that small and temperature as they change during fluctuations can also be detected. the charge or discharge cycle, the battery capacitance is indicated as Battery tests a function of the charge or discharge This example (Application Note cycle (FIG 3). REFERENCES 1CMAN25), which is somewhat more [1] Bues, D.; Stegmaier, J.; Vahldiek, D.: Indus- complex than the applications men- trial Controller PSM – Automated testing and control in production and lab. News tioned above, demonstrates the moni- Remote control of satellite antennas from Rohde & Schwarz (1994) No. 146, toring of various characteristics related This example (Application Note pp 19–21 to rechargeable batteries. The follow- 1CMAN10) demonstrates the FUP’s [2] Bues, D.: Industrial Controller PSM for pro- ing tests can be performed with this full range of functions in combination duction rationalization. News from Rohde & application: with PSM. The built-in microcontroller, Schwarz (1995) No. 147, pp 32–33 • determination of battery capaci- which has software that can be loaded tance, for particular applications, uses data • absolute and differential tempera- preprocessing to solve very complex ture measurement, measurement tasks. If a satellite anten- • monitoring of charging, na is controlled by a built-in controller, • discharge monitoring. the data signal is a sequence of pulses, Reader service card 152/15

News from Rohde & Schwarz Number 152 (1996/III) 41 Application notes

Fast adaptive data transmission on shortwave at up to 5400 bit/s with HF Modem GM2100

In HF Modem GM2100 (FIG 1), Rohde & Schwarz has now pushed the speed limits for data transmission even further. This modem from the XK2000 family of shortwave radio equipment [1] makes data transmission rates up to 5400 bit/s possible. Adaptive methods are used for matching the data transmission rate to the quality of the path: under favourable propagation conditions, transmission is at maximum speed, under less favourable conditions, the number of error control bits is increased. This results in a considerable increase in the effective data throughput for a typical shortwave link.

Data modem GM2100 has three signal formats for data transmission: • a Rohde & Schwarz signal format, • a signal format to MIL-STD-188-110A (single-tone method), • a signal format to STANAG 4285.

The R & S signal format is compatible with those of data modems GM857C4 [2] and GM2000. For GM2100 it was optimized to give data rates between 900 and 5400 bit/s. FIG 2 shows the structure of a frame with this signal format transmitted by GM2100. If GM2100 is used in conjunction with an ALIS processor [3], the transmission rate is automatically matched to the radio-link quality and to the require- FIG 1 HF Modem GM2100 for shortwave data ful signal processors came along. They ments of the transmission protocol, and transmission at up to 5400 bit/s made it possible to increase the data optimum utilization of the transmission Photo 42 569 rate to over 2400 bit/s, which became channel is also ensured. During link the standard for most shortwave setup, the ALIS processor automatically When it was first introduced, short- modems for a period of several years. calculates the maximum possible link wave data transmission was limited to 200 bit/s. This was because of the problem of multipath propagation in shortwave communications. Error 1 data block Further control methods such as FEC (forward data blocks Test sequence: error correction) and ARQ (automatic Preamble: 192 symbols Data + FEC: 48 symbols Postamble: 64 symbols 16 symbols repeat request) ensure minimal bit error 80 ms 26 2/ ms 26 2/ ms rates. Methods of compensating for 3 3 multipath effects could however not be developed cost-effectively until power- FIG 2 Frame structure of Rohde & Schwarz signal format for HF Modem GM2100

42 News from Rohde & Schwarz Number 152 (1996/III) Application notes

Modulation Info bits Redundancy bits Code rate FEC Net data rate and synchronous data rates between method [%] [bit/s] 75 and 4800 bit/s are possible. FEC 8PSK 144 0 No FEC 0 5400 for error control can be set according to 5 8PSK 120 24 /6 17 4500 2 the selected transmission speed. Inter- 8PSK 96 48 /3 33 3600 1 leaving of the transmitted data with an 8PSK 72 72 /2 50 2700 1 4PSK 36 36 /2 50 1800 interleaver length between 0.6 and 1 2PSK 18 18 /2 50 900 4.8 s can also be selected.

TABLE 1: Possible data rates for Rohde & Schwarz signal format for HF Modem GM2100 For transmissions using STANAG 4285 signal format, similar data rates as with MIL-STD-188-110A can be achieved by means of various modulation methods.

Typical data volume Typical data volume Data Transmission Here too, a long or short interleaving non-compressed compressed reduction time with GM2100 time can be selected. Text 2.5 Kbyte/page 0.9 Kbyte/page 64 % 2.5 s Fax 30 Kbyte/page 24 Kbyte/page 20 % 63 s Although MIL-STD and STANAG signal Video 490 Kbyte/page 15 Kbyte/page 97 % 44 s formats do not allow as high a data throughput as the R&S signal format, TABLE 2: Data transmission times for typical shortwave applications their availability on GM2100 ensures interoperability with stations using these standards. GM2100 gives maximum transmission rates at low BERs, making shortwave data transmission technically comparable with worldwide satellite transmission or PTT lines. Günter Wicker; Gerhard Greubel data rate. This gives full compatibility rate. Even though the quantity of these with the Rohde & Schwarz series data in relation to the user data is HF850 and XK2000 HF systems. vanishingly small, the protocol data are extremely important for the trans- The HF modem phase-modulates the HF mission protocol. This intelligent control carrier, using 2PSK, 4PSK and 8PSK. function therefore greatly enhances 2PSK is used for a data rate of 900 bit/s data transmission reliability. and 4PSK for 1800 bit/s. As fewer phase states are used for transmission, The high transmission speeds achiev- 2PSK and 4PSK increase the reliability able, in conjunction with the RSX.25 of data transmission for links of lower protocol, give a synchronous data rate quality. 8PSK is used for high-quality of 3600 bit/s at the data terminal in- HF paths. To further increase the data terface for high-quality radio links. This rate in the latter case, the redundancy corresponds to an asynchronous data REFERENCES of the FEC of a transmitted block can rate of 4480 bit/s for an interface set- [1] Helmke, B.; Wachter, G.: HF Transceiver be adjusted. In this way, transmission ting with eight data bits, one stop bit XK2100 – Digital shortwave for future-proof, long-haul communication. News from Rohde rates up to 5400 bit/s can be achieved and no check bit, ie to a practically con- & Schwarz (1994) No. 144, pp 4 – 7 (TABLE 1). tinuous data stream of 4500 baud. [2] Hackl, H.: Secure data transmission with TABLE 2 shows the data transmission 2700 bit/s on shortwave links. News from A great advantage of the transmission times for an HF system with System Pro- Rohde & Schwarz (1994) No. 146, method employed by GM2100 is cessor MERLIN [4], HF Transceiver pp 29 – 31 automatic detection of the received XK2100, the ALIS processor and HF [3] Greiner, G.: Reliable shortwave with ALIS. News from Rohde & Schwarz (1987) signal data rate by means of a code Modem GM2100. No. 116, pp 47 – 50 received at the start of reception. This [4] Kneidel, T.: System Processor MERLIN means that the receiving data modem For transmissions using standardized GR2000 – Powerful processor stands toughest need not be told the data rate of the signal formats to MIL-STD-188-110A, conditions. In this issue, pp 12 – 13 transmitting modem. The ALIS proces- 8PSK at a rate of 2400 symbols per sor makes use of this feature and trans- second is employed. Asynchronous mits RSX.25 protocol data at a lower data rates between 75 and 4800 baud Reader service card 152/16

News from Rohde & Schwarz Number 152 (1996/III) 43 Refresher topic

Digital modulation and mobile radio (III)

√—l 2 Basic modulation 2.5 Correlation and distance DBPSK = 2 E for BPSK (s2 = –s1). techniques between signals There are two distance values for √—l √—l √—l The parameters used to represent in- QPSK, Dmax = 2 E and Dmin = 2 E. formation are not the only differences 2.4 Frequency-shift keying between the various types of modula- The Euclidean distance for FSK depends All the types of modulation described tion. There are also differences in their on the modulation index; in the case so far have been linear. The (double sensitivity to external interference and, of CPFSK with a modulation index of √—l √—l sideband) baseband spectrum is as mentioned previously, efficient use of 0.5 DCPFSK = 2 E. This is the basis shifted linearly in the RF range. The the available RF bandwidth. A number for the modulation technique used for modulators used are memoryless as of parameters that indicate how well a GSM radio networks. neither the instantaneous phase ϕ(m) modulation method can transmit infor- nor the instantaneous amplitude a(m) mation on a particular radio channel are functions of previous values ϕ(m-p) have to be considered. In chapter 1, or a(m-p). modulation was defined as the assign- 2.6 Coherent demodulation ment of one of the M possible signals When RF signals are phase-modulated, Another way of transmitting digital that could be transmitted to a block of the resulting spectrum does not have a signals is mapping the M-ary base- k bits. The signal is distorted during component at the carrier frequency. band signals onto RF signals with M transmission. The purpose of demod- This means that the relationship different frequencies. This type of modulation in the receiver is to detect the between the current phase which car- ulation is referred to as M-ary frequen- signal in the presence of the noise ries the information and the phase of cy-shift keying (FSK). FSK is not linear which has been introduced during the unmodulated carrier is not directly and the RF spectrum is a Bessel spec- transmission and to distinguish it from available. Therefore, a complex method trum which has frequency components the other M -1 signals that could have is used to regenerate the carrier so that that are not present in the original sig- been sent. It is obvious that a mod- it has its original frequency and phase. nal. ulation technique based on a set of There are several frequency synchron- M signals can best fulfil its task if these ization techniques that can be used, for A simple form of frequency-shift key- M signals are as different from each example squaring the modulated signal ing with no memory can be imple- other as possible. Mathematically, once or twice and then dividing the mented by switching between M oscil- the degree of similarity between two doubled frequency by two (BPSK) or the lators each with a different frequency. signals is expressed in terms of their quadrupled frequency by four (QPSK). When this is done, the phase of the RF correlation factor Another approach is to periodically signal is random. The disadvantage transmit an unmodulated frequency of this type of FSK is that the RF spec- ͐ which the local oscillators in the re- s1(t) · s2(t)dt trum has large sidelobes. Frequency- ρ = —T ————————— (13) ceiver can lock onto. Usually the exact ͐ 2 shift keying with continuous phase s1(t)dt phase is obtained by means of special T shifts (continuous phase frequency- sequences (training sequences) con- shift keying, CPFSK) does not have or in terms of their Euclidean distance tained in the datagrams. The cross- this drawback. A CPFSK modulator correlation of the received sequences can be implemented with a voltage- D2 = ͐[s (t) – s (t)]2 dt with identical sequences stored in the 1 2 controlled oscillator (VCO) or an I/Q T receiver provides phase corrections for ———l = E + E – 2√E · E · ρ (14) modulator. 1 2 1 2 the local oscillators.

Binary FSK is the simplest form of where E is the mean energy over the A signal of the form cos(2πft) and an FSK and is described in terms of the duration of the symbol. orthogonal signal of the form two signals –sin(2πft) = cos(2πft + π/2)

When E1 = E2, as is the case with PSK are recovered from the regenerated π ∆ s1(t) = A · cos[2 (fc + f)t] and FSK, this equation simplifies to carrier. 2 ρ D = 2 · Ebit · (1– ). (15) and (12) Both components are multiplied by the π ϕ For binary ASK (s2 = 0) this formula received signal A(t) · cos(2 ft + (t)) π ∆ √—l s2(t) = A · cos[2 (fc – f)t] gives a distance DASK = E and and the following are obtained:

44 News from Rohde & Schwarz Number 152 (1996/III) Refresher topic

A(t) · cos(2πft + ϕ(t)) · cos(2πft) cos (2 π f t) = ––1 A(t)[cos(ϕ(t)) + cos(4πft + ϕ(t))], 2

π A(t) · cos(2πft + ϕ(t)) · cos 2πft + –– [ 2] c (t) π l = ––1 A(t)΄cos ϕ(t) + –– 2 [ 2] π + cos[4πft + ϕ(t) + ––]΅. (16) 2 cQ(t) A(t) • cos (2πft+ϕ(t))

FIG 7 The following terms remain when RF -sin (2 π f t) Coherent components are filtered out (FIG 7): demodulation

––1 A(t)[cos(ϕ(t))] 2 and (17)

π ––1 A(t)΄cos ϕ(t) + –– ΅= ––1 A(t)[–sin(ϕ(t))] transmission channel. Indeed, after However, a more careful analysis of the 2 [ 2] 2 transmission through a channel that band-limited RF signals and their suit- only adds white noise to the wanted ability for radio transmission gives However, as equation (3) shows, these signal, referred to as an AWGN an entirely different perspective. Band- are the modulating signals of the I and channel (added white Gaussian noise), limited M-ary PSK exhibits spurious inci- Q carrier components to within a con- BPSK is optimal with respect to the dent AM modulation of the RF carrier. stant factor and, as equation (6) shows, bit error rate as a function of the bit The reason for this is that the magnitude they are the components of the complex energy to noise power density ratio of the RF signal vector changes during envelope of the modulated signal to Ebit/N0. This type of modulation is, phase transitions which are slower than within the same constant and the sign therefore, used as a benchmark for those that occur with modulation with- of the imaginary part. If the original other types of modulation. The band- out band-limiting. This effect is particu- data are to be recovered, the inverse width efficiency is inadequate how- larly marked when the phase changes of the mapping onto the signals cI(t) ever. Although M-ary PSK and QAM by 180° (transition from 00 to 11 for and cQ(t) or onto the complex envelope have considerably better bandwidth BPSK and 10 to 01 for QPSK), the u(t) must be found. efficiencies, they exhibit small Euclid- carrier being reduced to zero for a ean distances, which means that their time. The carrier is reduced to 0.7 of Coherent demodulation must be used susceptibility to noise on the transmis- its maximum value when the phase for systems using true phase modula- sion path increases as the number of changes by 90° and to 0.38 of its max- tion, provided that differential coding is signal states increases. The implemen- imum value when the phase changes not used for the data. When phase tation of modulators and demodulators by 135° (possible phase shift for 8-PSK) shifts and not absolute phases are used also becomes more and more involved – this is equivalent to attenuation of to encode information, this is referred as the complexity of the modulation 8.4 dB. This precludes the use of effec- to as differential coding. Coherent de- technique increases. tive but nonlinear C-class amplifiers in modulation can, however, be used for mobile radios and means that linear all other types of modulation. In gener- Ostensibly, when compared with BPSK, A-class amplifiers are required for al, it performs better than non-coherent QPSK seems to be a good trade-off the output stage. It also makes it more methods, ie lower bit error rate for the between efficient use of bandwidth, difficult to recover the carrier from the same ratio of bit energy to noise power immunity to noise and technical com- modulated signal, which is essential for density. plexity because of its mean minimal coherent demodulation. difference in Euclidean distance and 3 Modulation methods for its bandwidth efficiency, which is twice To be continued Peter Hatzold mobile-radio networks as good. By contrast, CPFSK as implemented in GSM networks requires far The last chapter would lead one to more complex hardware and so on conclude that BPSK has the greatest the face of it does not appear to be the immunity to noise introduced by the optimum choice.

News from Rohde & Schwarz Number 152 (1996/III) 45 Software

PropWiz – Windows program for shortwave radio link prediction

Propagation Wizard, or PropWiz, is a new program which allows the quality of a shortwave link between any two points in the world to be predicted in an extremely easy way. Propagation Wizard calculates the reliability of a link, ie the available time for a desired S/N ratio and the appropriate frequency range. Results are displayed as well laid-out graphics on a monitor (FIG). Colour printouts can be produced on any colour printer. The avail- Result printout of shortwave link able time for a link is indicated in hours calculation made with per day. Propagation Wizard

A free demo version of this program is now available for the first time from the Rohde & Schwarz Web site and can be downloaded by anyone wanting to try it out (address: http://www.rsd.de). ideal for the exhaustive, high-reliability Propagation Wizard spares the user all analysis of large and complex radio this work and gives the result in no time. With its simple, self-explanatory user networks, including all interconnec- Calculations can be performed with interface (Windows 3.x or 95) and the tions, at a relatively high speed. slightly altered parameters any number high forecast quality, Propagation Previously, calculations of this kind had of times, allowing the effect of specific Wizard is unique on the market. It to be performed using the following parameters to be determined (eg mini- takes into account the characteristics of sequence of steps: mum required transmitting power). Rohde & Schwarz transceivers of all power classes (HF850/XK2000), 1. Calculation of the field strength at Here are the special features of Propa- modulation methods (eg Data Modem the reception site using a program. gation Wizard again at a glance: GM2000) and, most importantly, 2. Determination of all noise and inter- the characteristics of transmitting ference at the reception site by means • extremely easy operation through and receiving antennas (eg HX002, of CCIR tables (depending on place, self-explanatory Windows user inter- AK471). The vertical radiation pat- time of day and season). face, terns (ie gain as a function of elevation 3. Calculation of S/N ratio taking into • Windows help function (context- angle and frequency) are used in account inherent receiver noise, band- sensitive) always available in the calculation. Customer-specific require- width and the receiving antenna. background, ments and parameters can easily be 4. Comparison of calculated S/N ratio • based on proven algorithms, implemented. with minimum nominal ratio for modu- • includes all relevant shortwave link lation method used. parameters in the calculation, To determine S/N ratio, not only the 5. 24-fold repetition of steps 1 to 4 for • takes into account the characteristics received field strength but also all hours of the day. of Rohde & Schwarz shortwave atmospheric, galactic and man-made 6. If input parameters were changed, system components, noise at the site of reception are taken (eg to correct antenna gain for the • takes into account the vertical into account in accordance with calculated frequency range), all patterns of Rohde & Schwarz anten- the relevant CCIR recommendations. previous steps had to be repeated. nas, Thanks to Propagation Wizard, the 7. All calculations and evaluations • calculates the available time and complex chain of link-quality calcu- had to be repeated for new transmis- optimum frequency range for a lations can now be performed by just sion or reception sites. shortwave link, pressing a key or clicking a mouse. 8. Results had to be presented as • displays results as graphics on the Propagation Wizard is, therefore, also graphics for a full assessment. monitor,

46 News from Rohde & Schwarz Number 152 (1996/III) Software

• outputs colour hardcopies on a • laptop/notebook version (640 x make a complete assessment of Propa- printer, 480 pixels). gation Wizard. • performs all calculations very rapidly. Dr. Hans Waibel; Peter Maurer Both versions are available as free Propagation Wizard is available in demos with Munich as the reception two versions: station. All features of the program • standard version for normal PC including the printing function are avail- (min. 800 x 600 pixels), able, allowing prospective users to Reader service card 152/17

Frequency-selective measurement and display of frequency-dependent test parameters Patent

In the field of RF measurements, there are an in- amplitude versus frequency characteristics of a four- which is very useful for aligning DUTs. The display of creasing number of analyzers for frequency- terminal network. There are also vector network frequency or test parameter markers, eg level selective analysis of frequency-dependent test pa- analyzers that can measure both magnitude and markers, or of test parameter tolerance lines, eg rameters over a frequency range of interest. For phase. From the magnitude and phase, the nominal level lines, during the measurement makes example, there are spectrum analyzers that display impedance of a device under test (DUT) can be the patented analyzer a highly versatile instrument the amplitude of a test signal as a function of calculated, for example, and from the phase/ suitable for a wide variety of measurement tasks, eg frequency over a wide frequency range in nearly frequency curve the group delay. Network analyzers for measuring the selectivity characteristics of high- realtime on a CRT (eg Spectrum Analyzer FSA from of this kind can, therefore, be used for measuring a pass, lowpass, bandpass or bandstop filters. The Rohde & Schwarz). There are also network wide variety of DUT parameters. The main problem patented analyzer can also be used for displaying analyzers which have a tracking generator as well with all the analyzers that have been referred to is, various selectivity characteristics of a multiport DUT, as the frequency-selective analyzer (eg Scalar Spec- however, that they cannot be adjusted to obtain for example a diplexer consisting of a lowpass and trum and Network Analyzer FSAS). Network ana- optimum accuracy and measurement speed for a a highpass filter, in which case a multichannel lyzers of this kind can be used for measuring the specific measurement task or DUT. instrument would have to be used.

The purpose of the invention is to provide an analyzer similar to the one initially described that can be optimally tailored to the measurement task to be performed. This problem is solved for an analyzer as described in the preamble of the main claim through the characteristic features of the analyzer. Useful further developments, in particular for the design of Micro- processor a network analyzer, result from the subclaims. The invention provides for optimum adjustment of frequency scaling (number and distribution of the frequency steps) and the scaling of the test parameters (eg amplitude, phase, impedance and High- Frequency- frequency DUT selective Display group-delay scaling) to a specific task in various Extract from patent specification EP 473 949 B1 generator meas. unit subranges of the overall frequency range. For Applied for by Rohde & Schwarz on 11 March example, when measuring the transfer character- 1992 istics of a lowpass or highpass filter, the overall Issue of patent published on 21 June 1995 frequency range of the network analyzer is divided Inventor: Klaus Danzeisen Level Level into two subranges (passband and stopband), and marker marker Frequency marker measurements are performed in the two subranges Used in Vector Network Analyzers ZVR using different frequency scales and different test Scale Scale Level tolerance line unit 10 dB unit 20 dB parameter scales (FIG). To perform measurements on a bandpass or a bandstop filter, it is expedient to Frequency Scale divide the total frequency range into three adjacent marker unit 1 dB subranges, with the scaling of each range adapted Frequency Level marker marker to the filter passband and stopband ranges, the middle range having higher frequency and level resolution than the neighbouring stopband ranges. 1 10 100 990 1000 1010 2000 MHz 4000 Since the patented analyzer allows the user to select Reader service card 152/18 for further the number of frequency steps per subrange, the Lower Upper information on ZVR stopband Passband stopband analyzer’s measurement speed can be optimized,

News from Rohde & Schwarz Number 152 (1996/III) 47 Panorama

Digital Radiocommunication Tester CMD55 with new measurement functions

To speed up the remote-control mode, the outgoing and incoming remote- control commands are displayed on the CMD screen, but not the menus required for manual control. This command display function is extremely useful for writing and testing remote-control programs in the test phase. In normal operation the command display function can be disabled, giving a further increase in speed. When used in automatic repair test setups, CMD can be directly switched over from remote to manual. The menu level and the signalling status are retained however. This means that immediately after fault detection by the automatic test program, FIG 1 Digital Radiocommunication Tester mobile subscriber identity) is known, the fault can be analyzed in more detail CMD55 Photo 40 946 as a direct call can be made from the using the graphics menus in the manu- mobile to CMD (direct paging). Produc- al mode. tion departments generally use a test SIM card with a known IMSI. The processing speed of the hardware components in CMD55 has also been CMD55 (FIG 1) is a compact unit for Production tests on mobile phones have increased thanks to a faster micro- testing GSM, PCN and PCS mobile to be performed at different TX powers. processor system. The modular design phones in advanced service and The signalling procedure required for a of CMD means that the new controller production environments [1; 2]. The power change is also very elaborate. module can also be retrofitted to test tester has been upgraded with a variety Here too, test duration can be cut by systems that have already been of new measurement functions to changing channel in CMD to change supplied. comply with the latest requirements for TX power, ie by choosing the same these application areas. channel but with different power. The The following new features enable signalling procedure is much shorter in CMD55 to be used in development and The following new characteristics make this case. quality assurance of mobile phones. CMD55 ideal for use in mobile-phone production:

To measure the RF parameters of mobiles, the tester has to simulate a base station so that a call can be set up. The complete signalling procedure for a location update requires up to 10 s, but this may be too long for a production environment. CMD has two ways of saving valuable processing time. As well as the complete signalling procedure, there is also an abbreviated signalling mode where all signalling messages not required for testing are eliminated. Testing can be speeded up even further if the IMSI (international FIG 2 Timing advance test menu FIG 3 Network definition menu

48 News from Rohde & Schwarz Number 152 (1996/III) Panorama

A GSM phone has to have the correct conjunction with the AF measurement Prior to measurements, discontinuous frequency and time slot synchro- unit comprising a voltmeter, distortion reception or discontinuous transmission nization with respect to the test setup meter, bandpass filter and AF genera- can be set on the mobile phone. Ca- which is acting as the base station. tor (option CMD-B41). After making a pabilities like setting the mobile out- CMD can measure how early or late connection to the AF interface of the put power or choosing “registration the mobile is transmitting, ie it performs mobile’s hands-free facility or attaching barred / not barred” mean that CMD a timing error measurement. A timing an acoustic coupler, the AF character- can handle very specialized applica- advance test can also be performed. In istics of the mobile can be measured tions. this case CMD tells the mobile by how precisely. Werner Mittermaier much it should send too early or late so that it can make a correction and The user of CMD55 may specify a num- then measure the time offset (FIG 2). ber of signalling parameters (FIG 3) to This function is required for delay cor- simulate different networks for exam- REFERENCES rection when base stations are a large ple. This means that the roaming be- [1] Mittermaier, W.: Module test with Digital distance away. haviour of mobiles can be tested in the Radiocommunication Tester CMD52/55. home network, or in others, by using News from Rohde & Schwarz (1995) No. 149, pp 36 – 37 To check the dynamic RF characteristics special network SIM cards. If there are [2] Vohrer, M.: Multimode Radiocommunication of mobile phones, one of CMD’s four a large number of neighbouring cells, Tester CMD for GSM, PCN, PCS and DECT different frequency hopping sequences the mobile’s hardware and software mobiles. News from Rohde & Schwarz (1996) can be activated by a simple keystroke. have to handle the increased load. To No. 150, pp 53 – 54 A realtime speech coder/decoder assess the effects of the extra workload, (option CMD-B5) is available for meas- the type of neighbouring cell and uring AF parameters. It is operated in their number can be selected on CMD. Reader service card 152/19

ACCESSNET® – a solution for communications in Russia

Following market liberalization there is only limited availability to the user. In large demand for telecommunications industrial centers, mobile telephone in Russia which cannot be met by the networks to NMT and GSM standards existing telephone network. Telecom- are being implemented, but this means munication facilities in Russia have not enormous investment and operating reached the same level as those in costs for the network operators and highly developed industrialized na- subscribers. tions. There are many places where the copper-based PSTNs are obsolete, The ACCESSNET ® trunked-radio overloaded and unable to cope with system from Rohde & Schwarz, based the growing demand. on the European MPT 1327 signalling standard, is the ideal solution for the re- In the wake of the free-enterprise quirement profile of potential network economy, private network operators operators and users in Russia. Thanks are investing in mobile communication to modular design, communication networks. Most of these systems are systems from compact local systems to patched together from conventional regional and supraregional trunked FIG 1 Russian type-approval certificate for radio components, offering a limited radio networks can be implemented Rohde & Schwarz base station ND950 for pri- range of functions and in most cases at comparatively low investment cost vate trunked-radio networks

News from Rohde & Schwarz Number 152 (1996/III) 49 Panorama

was given top priority. Rohde & Schwarz is now one of the first manufacturers to be granted a Russian certificate for a trunked-radio system – ACCESSNET ® (FIG 1).

The multi-faceted marketing activities have begun to bear fruit. Joint projects were implemented with local system integrators in Moscow and Novosibirsk (FIG 2). Two systems are already in operation, four others are to be installed shortly. Operators of the trunked-radio networks make useof the whole application spectrum of ACCESSNET ® as a public mobile radio system and for security services, harbour authorities and railway companies. The flexibility of ACCESSNET ® and its network architecture which is unique on the market, as well as Rohde & Schwarz’s expertise with high-performance systems, are powerful arguments for Russia to choose ACCESSNET ® as a solution to its communication problems. Andreas Schneider

FIG 2 Presentation of ACCESSNET ® trunked- is for a great number of conventional REFERENCES radio system at SIBCOM telecommunications systems. If licences are granted to [1] Wagner, K.-H.: Trunked-radio systems suc- show in Novosibirsk Photo: author selected network operators who make cessful all along the line. News from Rohde & Schwarz (1994) No. 146, p 55 their network infrastructure available to [2] Schinke, U.; Klier, W.: Radiocommunication various user groups, more efficient use System ACCESSNET ®-D – Trunked radio can be made of the available fre- goes digital. News from Rohde & Schwarz quency resources. (1995) No. 149, pp 28 – 31 [3] Wagner, K.-H.: A vision comes true – trunked [1 to 3]. The multitude of supplemen- Rohde & Schwarz anticipated the radio for United Arab Emirates. News from Rohde & Schwarz (1995) No. 151, tary call types and data transmission fa- demand for communications in Russia pp 50 – 51 cilities of these systems offers a much early on, and since 1994 has been wider range of services to the subscri- seeking closer cooperation with ber than any cellular phone system. Russian partners to consolidate a basis for future business relationships. Since Supraregional frequency assignment type approval of the ACCESSNET ® for trunked-radio systems by the appro- trunked-radio system is a precondition priate authorities is much easier than it for supplying and commissioning, it Reader service card 152/20

50 News from Rohde & Schwarz Number 152 (1996/III) Panorama

Rohde & Schwarz test equipment in EMC test center of safety standards authority of Hesse

above 10 kHz. It includes a Signal Generator SME, a relay matrix, three power amplifiers, a Millivoltmeter URV5, a field-strength test system, a transmitting antenna as well as coupling networks. The test system, which features higher power in the lower frequency range, is suitable for the future development of standards. If required, measurements with different antennas are possible from 1 MHz up- wards. The amplifiers can be manually or remotely controlled by means of the computer.

An EUT monitoring system transmits electrical signals from the equipment under test to the operator’s position via fiber-optic cables. There the signal FIG 1 EMC test system of safety standards for manufacturers and importers of elec- parameters can be read off the volt- authority of Hesse tronic instruments and systems of up to meter or collected and logged by the approx. 2500 kg. computer. A video and audio system The EMC laboratory of the safety stan- also operating via fiber cables is used dards authority of Hesse (TÜH) offers The computer-controlled EMS test for the visual and acoustic check of the the whole range of measuring and system from Rohde & Schwarz, for EUT function. The computer-controlled testing facilities for electronic equip- example, allows measurements for EMI test system offers application- ment of any kind. The test equipment is acceptance tests to IEC 1000-4-3 and oriented facilities for measuring EUTs designed for measurements of electro- IEC 1000-4-6 in the frequency range of up to 2500 kg on 3-m turntables in magnetic susceptibility (EMS) in the fre- the anechoic chamber and at the open- quency range 10 kHz to 2 GHz and area test site. A sheltered building electromagnetic interference (EMI) in made of special plastics is designed for the range 5 Hz to 18 GHz. The meas- open-area testing at distances of 3 and uring and test equipment supplied 10 m independent of the vagaries of by Rohde & Schwarz (FIG 1) allows the weather. fast testing and flexible adaptation to different DUTs; the associated software All measurement rooms have a 3 x ensures optimum utilization of the ane- 32 A power supply, a large number choic and shielded chambers installed of power supply units for ancillary by Siemens (FIG 2). facilities as well as compressed-air, water, sewage and waste gas connec- In the Kassel branch of the Hesse tions. Regular servicing and calibration technical authority, new buildings for of the measurement and test systems laboratories and offices as well as an guarantee high quality and reliability of open-area test site occupy more than the results. 2000 m2; large rooms allow testing Klaus Wunderlich (TÜH); to directives on EMC, machinery and Peter Busch low-voltage equipment. Thanks to its central and easily accessible location as well as its powerful technical outfit, FIG 2 Anechoic chamber in Kassel Reader service card 152/21 for further infor- the laboratory is an interesting partner Photos: Eberth mation on EMC test equipment

News from Rohde & Schwarz Number 152 (1996/III) 51 Panorama

SNCB uses R&S test system for planning and quality assurance in Belgian railway communications

Railway communications test system of SNCB with two Test Receivers ESVS10, one ESN and three PCs Photo: SNCB

The red carriage that can be seen on work has gone into operation. To do trollers PSM, one for data acquisition, the lines between Louvain and Aarschot this, the carriage has to travel the entire one for statistical analysis of the data or Gembloux and Namur in Belgium Belgium rail network in both directions and one for printing out, protocolling looks a bit bizarre. Its job is to measure twice a year. and presenting the data as graphics on the field strength of transmissions in the a laser printer. The field strength values radio network linking trains and base The test system is controlled by pulses are also output on a YT plotter at the stations. Several years ago SNCB from a tachometer attached to one of same time, but without statistical analy- (Societé nationale des chemins de fer the carriage’s axles. Spurious results sis. The software used was specially belges) decided to set up a radio net- due to superposition are eliminated by designed for railway applications by work linking trains and the railway con- performing three measurements (as Larisys, a French company. trol center and ordered the test system three radio frequencies are used) every they needed from Rohde & Schwarz three centimeters – at speeds of up to Finally it should be mentioned that the (FIG). The system is not just for the na- 200 km/h. The results are analyzed carriage is also equipped with an office tional rail network but will also be used statistically to determine whether there for field work, a workshop, a kitchen for Eurostar, Thalis and the planned is a 95% probability of the 6 dB and a small room with a boiler and a Paris – Brussels – Cologne – Amster- threshold being exceeded on the generator. “They could send us to the dam rail link. national network (95% of the time and middle of Siberia”, quipped the crew. 95% of the coverage area); for high- “If we had an oil supply, we’d be totally “If the radio network is to work speed lines 98% is the requirement. self-sufficient.” properly, call setup must be reliable Jacques Stellamans (SNCB Brussels) and there must be no lost call, in other Only 540 ms are available for measur- words the received field strength must ing and processing the measurement be adequate at all times”, explains the results, displaying them in realtime engineer responsible at the radiocom- and generating graphs and tables. Of munications department in the SNCB’s course, this can only be achieved by a infrastructure laboratories. The test car- really fast system. Rohde & Schwarz riage has two functions. Firstly, it is used uses three test receivers operating at a to determine the number and positions fixed frequency around 460 MHz: one of the base stations. Secondly, it is used ESN and two ESVS10s. The equipment Reader service card 152/22 for further infor- to check the field strength once the net- used also includes three Process Con- mation on railway communications test systems

52 News from Rohde & Schwarz Number 152 (1996/III) Information in print

Audio Analyzer UPL has evolved out of UPD Receiver Part CT200RP (45 to 862 MHz; IF con- Terrestrial Flight Telecommunication System (but has fewer functions and slightly restricted version), TV Receiver CT200RA (45 to 862 MHz; JETCALL (1670 to 1675/1800 to 1805 MHz) specifications), is compatible with UPD and suit- baseband conversion), Satellite Receiver CT200RS The data sheet presents airborne equipment (to able for mobile use; various options, eg digital (950 to 2050 MHz; baseband conversion, option: ETS and ARINC) for public radiocommunications. audio interfaces. ADR decoder) and QAM Modulator CT200QM Data sheet PD 757.2296.21 enter 152/44 Data sheet PD 757.2238.21 enter 152/23 (31 to 41 MHz; modulation of MPEG-coded video/audio signals onto IF) are extensions to Radiolocation System NetTrap consisting of up to GSM Go/NoGo Tester CTD52 and GSM/DCS the modular TV system CT200. The data sheets four Direction Finders PA1555 (20 to 1000 MHz), Go/NoGo Tester CTD55 The data sheet has for Controller CT200CO, Upconverter CT200UP Software WinLoc and a laptop enables full-duplex been revised to include the new CTD55. and Vision/Sound Modulator CT200VS have voice and data transmission. been revised. Data sheet PD 757.1502.22 enter 152/24 Data sheet PD 757.2315.21 enter 152/45 Data sheet CT200- CO PD 757.0735.22 enter 152/36 VHF/UHF Direction Finder DDF190 (20 MHz Digital Radiocommunication Testers CMD54, QM PD 757.1890.21 enter 152/37 to 3 GHz) The revised data sheet furnishes CMD57 The data sheet has been completely RA PD 757.1877.21 enter 152/38 detailed information about bearing accuracy as revised and expanded especially with regard to RP PD 757.1860.21 enter 152/39 well as general features. applications and options. RS PD 757.1883.21 enter 152/40 Data sheet PD 757.1460.22 enter 152/10 Data sheet PD 757.1231.23 enter 152/25 UP PD 757.0729.22 enter 152/41 VS PD 757.0712.22 enter 152/42 Radio Paging Systems with Multi-Protocol Capa- Type Approval Systems for Mobile Radio This bility This brochure from R&S BICK Mobilfunk brochure gives an overview of all systems avail- describes the infrastructures of national and local able. systems for public paging operators. Info PD 757.2321.21 enter 152/26 Info PD 757.2367.21 enter 152/46

TETRA – Trans European Trunked Radio for Software TS51K1 and TS55K1 ensures fast, effi- Professional Mobile Radio This brochure from cient and economical measurements when used R&S BICK Mobilfunk informs about features, ba- with GSM Coverage Measurement Systems sic and extra services of the new transeuropean TS9951 or TS9955 from Rohde & Schwarz. standard. Data sheet PD 757.2415.21 enter 152/27 Info PD 757.2373.21 enter 152/47

Shielded TEM Line S-LINE (150 kHz to 1 GHz) The world of test and measurement – our name for EMS measurements with Rohde & Schwarz is synonymous with accuracy is the title of a bro- equipment is of compact design and available in chure which presents the Test and Measurement Ω two sizes; 50 , VSWR <3, max. 100 W. Division of Rohde & Schwarz. The four strong Data sheet PD 757.2338.21 enter 152/28 pillars of test and measurement are mobile radio, EMC, general-purpose and RF measurements as EMI Software ES-K1 The range of drivers has well as systems. been expanded, the screen pictures have been Info PD 757.2450.21 enter 152/48 updated. Data sheet PD 757.0406.22 enter 152/29 New application notes

Network connection to a server via network card EMI Test Receivers ESHS (9 kHz to 30 MHz) and with CRTS/P/C ESVS (20 to 1000 MHz) Receiver models 10 and Appl. 1CPAN04E enter 152/49 30, which are still available, are now presented in a single revised data sheet. Measurement of transient responses in AGC Data sheet circuits using Audio Analyzer UPD or UPL ESHS PD 756.3260.22 enter 152/30 Appl. 1GPAN32E enter 152/50 ESVS PD 756.9422.22 enter 152/31 Measurement of spurious emissions of GSM, Peak Power Sensor NRV-Z33 (30 MHz to 6 GHz; DCS1800 and DCS1900 transmitters with spec- Ω 1 mW to 20 W; 50 ) Model 03 for TV trans- trum analyzers of the FSE family mitters and general-purpose measurements, model Appl. 1EPAN17E enter 152/51 04 for TDMA radio technology. Data sheet PD 757.2344.21 enter 152/32 Measurement of power ramps of GSM, DCS1800 and DCS1900 signals with spectrum analyzers Industrial Controller PSM Retrofit to Pentium of the FSE family (90 MHz) and 1-Gbyte harddisk as well as up- Appl. 1EPAN18E enter 152/52 date of range of options. Storing and loading complete test receiver data Data sheet PD 757.1048.23 enter 152/33 records via IEC/IEEE bus Appl. 1EPAN20E enter 152/53 Signal Generators SME and SMT (5 kHz to 6 GHz) Models 06 (6 GHz) are new in the Exchanging data records between different test product range. receiver models Data sheet Appl. 1EPAN19E enter 152/54 SME PD 757.0358.23 enter 152/34 SMT PD 757.0364.22 enter 152/35 Schz

News from Rohde & Schwarz Number 152 (1996/III) 53 Newsgrams

ILA 96 – Rohde & Schwarz with application-related background demonstrates its competence photos and a brief explanatory text. The international aerospace show in The logo for the show was “Compe- Berlin from 13 through 19 May 1996 tence in Avionics and ATC Comms”. was a real attraction this time round. A very professional and expert 216,000 visitors attended, some image was created by products 44 % more than two years ago. The selected from test engineering for main reasons were the interesting ATC, VHF-UHF ATC communication, exhibits and flight demonstrations traffic control with direction finders, of course, like the world première of military and civil avionics, mobile air Eurofighter 2000 and the NH90 traffic control and determination of multi-mission helicopter, and the position in traffic management with good weather also did its share. The GPS/DGPS. number of major international companies attending was also higher After experiencing all the modern this time, even though there is some technology, customers and visitors way to go before the likes of the were able to refresh themselves in Aérosalon in Le Bourget/Paris can the “Fliegerstüberl”, the centerpiece First DKD qualification instruments during transport and on- be matched. But the signs are very of the stand and extremely popular. for a mobile calibration lab site operation, encouraging, and the show’s claim Once again it could be seen that The Rohde & Schwarz Cologne Plant – maintenance of the required en- to be a gateway to markets in the east the show is a major event for both has received approval from the Phy- vironmental conditions on site and for German and international indus- customers and exhibitors, and it can sikalisch-Technische Bundesanstalt during transport, try seems to be bearing first fruit. only be hoped that the ILA really (PTB, German bureau of standards) – assurance of calibration of the stan- does fulfil its promise of becoming a to conduct DKD calibration and cer- dards in the superordinate, stationary Rohde & Schwarz was present on its success story, especially in its inter- tification at customers’ premises with DKD calibration laboratory at the own stand in a new design (photo nationalism and as a gateway to the the MKL04 mobile calibration labor- Rohde & Schwarz Cologne Plant. below). The exhibits were presented east. J. Frantzen atory. Certificates of the DKD (Ger- man calibration service) have a spe- In addition, the engineer performing cial advantage in that they are rec- on-site calibration obviously has to ognized internationally, without any be specially qualified. His workplace further verification, when a firm is in the MKL04 is an air-conditioned quality-audited. So the customer can compartment in a van body mount- be sure of traceability to national stan- ed on a truck chassis (photo above). dards as called for in ISO 9000 ff, There are four workstations for DC, EN 45001 and other specifications. AC and high-frequency measured This process of qualifying a mobile variables. Calibration on site natu- calibration laboratory in the Ger- rally has its benefits for the customer man calibration service broke new compared to calibration at a station- ground, so the requirements for it were ary facility. No time is lost for trans- set down in discussions between the port, and turnaround time is restrict- PTB and Rohde & Schwarz. They ed to the duration of calibration. went far beyond the demands made Calibration of Rohde & Schwarz on a stationary calibration lab of and other brands of equipment is course, and included single source, and visiting a custom- Photo: Gläser – measures for maintaining the cali- er in this way helps promote good bration status of the standards and contacts. H. Bremmekamp

EMI test system at Siemens Schwarz that is used here (photo left) in Munich consists of Test Receivers ESMI and The institute for quality engineering, ESVS30 and a controller for the trial and approval of Siemens in turntable and antenna mast. It works Munich operates a number of an- fully automatically in the frequency echoic chambers. The “giant an- range 20 Hz through 26.5 GHz (see echoic chamber”, brought up to the News from Rohde & Schwarz 142). latest technical standards in 1995 Operation is possible round the at a cost of some three million DM, clock, so tests can be conducted has a useful inner space of 18 m x faster and are more attractive in 11.3 m x 7.4 m and can take even terms of cost. Another two Rohde & the biggest EUTs. Thanks to its hy- Schwarz EMI test systems (ESH3/ brid absorbers, ie plastic absorbers ESVP/EZM) have been in operation compounded with carbon on ferrite for a number of years in three other plates, it now allows tests in line with anechoic chambers of the institute. the stiffer demands for field-strength The customers are divisions of Sie- instrumentation of ANSI-C 63.4, mens itself, international industry, CISPR 16 and CISPR 22. EMI Test state, civil and military bodies.

Photo: Geigl (Siemens AG) System TS9975 from Rohde & K. Geigl; D. Poltnigg

54 News from Rohde & Schwarz Number 152 (1996/III) Newsgrams

Satphone for CARE Canada Rohde & Schwarz receivers The CARE Canada organization, for British aviation authority In memoriam Dr. Rohde whose headquarters are in Ottawa, Britain’s CAA (civil aviation au- carries out emergency humanitarian thority) recently took delivery of 14 relief operations around the world. Rohde & Schwarz VHF receivers for So its workers need to be able to be Stansted Airport (right in the photo reached at any time and wherever below Derek McLauchlan, Chief they are, even in regions with poor Executive of NATS, part of the CAA, infrastructure, as is often the case. accepting the first unit from Wolf- For this reason CARE Canada or- gang Winter, Sales Director Europe dered SP1600 Inmarsat M satellite of Rohde & Schwarz). This is part telephones from Rohde & Schwarz. of a contract won five years ago, SP1600 provides CARE’s staff with during which time more than 1200 interference-free communication, VHF-UHF transmitters and receivers greater security and improved effec- have already been supplied for the tiveness. The digital Inmarsat M stan- CAA’s communications facilities. The high reliability of the equipment enables CAA technicians to carry out their work efficiently and without interruption. As Paul Bolden, project manager of national air-traffic services, put it: “On average the Rohde & Schwarz equipment is exceed- ing the contracted availability of 33,000 hours MTBF by about 60%. This has allowed us to consolidate our maintenance facilities. The modular construction of the equipment means that site engineers now only replace a faulty unit with the spare. The failed unit is then refurbished dard using four geostationary satel- as required at our central mainte- lites enables highly mobile, global nance unit before being tested and communication. Speech, data, fax returned as the station spare. Previ- On 4 October 1996 Dr. phil. nat. and pictures can be transmitted by ously many faults at component Dr.-Ing. E.h. Lothar Rohde would have direct distance dialling from just level were repaired on site by the been 90. He departed from us much about anywhere in the world to any engineer. This has reduced on-site too early in 1985. Dr. Rohde was not subscriber of the public telephone spares holdings.“ Bolden added: “A network (see News from Rohde & direct benefit of the revised mainte- only one of the founders of the compa- Schwarz 145 and 149). nance policy is that training require- ny. Until his death he was its technical ments have reduced considerably and scientific impulse. Dr. Rohde had The photo shows Christopher Cush- and training course duration has an infallible understanding of the chal- ing (left), senior program officer of now been cut by 50 %.” the emergency response unit of T. Stephens lenges posed by a customer’s require- CARE Canada, and Peter Foulger, ment and was able to respond with Vice President Sales and Marketing unique solutions. His first principle was of Rohde & Schwarz Canada, at speedy implementation of the ready the handover of an SP1600 satellite telephone in its briefcase version. product for key customers. D.G. Stephenson He challenged design engineers to go to the limits of what was possible, technically and in how fast they achieved it too. His visionary, pace-setting ideas, which he reported on in countless pub- lications all over the world and recorded in numerous patents, made a decisive contribution to Rohde & Schwarz’s worldwide reputation.

His maxims – intuition and care and concern for the customer – are a model and legacy for us today in moulding the company’s future.

Photo: Astonleigh Studio F. Schwarz; H. Wagner

News from Rohde & Schwarz Number 152 (1996/III) 55 Press comments

Bavaria live in China Optical and electrical test

The »Wirtschaftswoche« of 25 April 1996 report- This combination interested number 4/1996 of ed about a DAB demonstration, in which the vice- the English magazine »Test«, which looked at the minister of China’s ministry for broadcasting, film LV1 test system: and technology had an opportunity of gathering information on the status of the DAB project cur- The capabilities of LV1 really show through inte- rently under way in Bavaria: gration in a Rohde & Schwarz production testing system. The magic word is parallelization. The He Dong Cai shook his head in astonishment when steps of the electrical test (eg in-circuit test) and the the car radio announced: “Slow moving traffic on optical test run entirely in parallel without any time the circular and arterial roads in and around loss. But it is also possible to combine optical and Munich“. Bavaria live in China. The minister had electrical tests (eg display test, LEDs), substantially heard a warning to drivers sent over the air as part enhancing test depth and without the need for of Bavaria’s DAB (digital audio broadcasting) pro- extra tools or test time. ject. ...The DAB lobby has a further argument for potential customers like China: its know-how lead based on years of experience. The engineers of the Munich-based communications and test engineering specialist Rohde & Schwarz, for instance, have been looking into the possibilities of DAB since 1985 already. The biggest item on the agenda to date is the pilot project in Bavaria, costing 42 mil- Superlative of the superlatives? That was the lion DM. question put by the international magazine for radio »funk« in its June 1996 issue. It not only meant the automatic linear shortwave booster Ehorn Alpha 87 A from the US company ETO but also a spectrum analyzer that is absolutely top in its class, Rohde & Schwarz’s FSEA20, which the magazine’s engineers used for 122 tests to sound out this power amplifier.

Pinpointing by satellite

Elaborate searching for mislaid containers was a subject for the daily »Blick durch die Wirtschaft« on 23 April 1996:

Goods traffic by sea is largely handled with standard containers. Hamburg’s Hafen- und Lagerhaus CE labelling has been in force throughout the EU AG (HHLA) moves some 1.5 million of these big since the beginning of the year, and this was a boxes every year. ...Mislaid containers can be a topic for edition 1–2/1996 of the Austrian mag- nightmare when they are not found where they azine »Elektronik-Schau«. Under the title “EMC should be because of a mistake by the driver. precertification testing for everyone” it presented Tracking them down can be a long process, and EMI Test Receiver ESPC from Rohde & Schwarz as the ship has to wait in the meantime. Just one lay an attractively priced and straightforward test set day costs an average of 100,000 DM. So HHLA for EMC measurements parallel to the production asked Rohde & Schwarz to devise a means of process. searching for them. It works by satellite location with GPS (global positioning system) and there are two versions of it. ...But often it is still not accurate enough. So Rohde & Schwarz then came up with differential GPS, increasing accuracy to about one meter.

Constantly on the move, the mobile units of the Digital Video Component Analyzer VCA served new radiation test squad of the German army, as an eye catcher for the cover of the April 1996 most of whose equipment came from Rohde & edition of the English monthly magazine »TVB Schwarz. In edition 6/1996 of »Soldat und Tech- Europe«. VCA combines the conventional testing nik«, a magazine for defence technology, arma- skills of analog TV waveform monitors with whole ments and logistics, author Harald Konrad spoke new functions for monitoring digital coding and of the job of this service: radiation tests on equip- signal transmission. It allows in-depth analysis of ment and systems, buildings and rooms, etc. data content and examination of the data frame.

56 News from Rohde & Schwarz Number 152 (1996/III) Final article

Digital broadcasting and multimedia communication

In the past decades, classic broadcast- Satellite reception ing, namely sound and TV broadcasting, used to be a field of its own with specific developments, largely independent of the world of telecommunications and computers.

Cable Receiver/decoder Domestic TV receiver Video workstation Sound broadcasting

Analog sound broadcasting, using amplitude modulation for longwave, CD player Cassette recorder shortwave and mediumwave and frequency modulation for VHF, more or FIG 1 less retained its principle of sound trans- Scenario for utilization of DVB [1] Terrestrial reception ISDN Video CD Digital video cassette mission over the past decades. The only innovation was the radio data system (RDS), which was specified in 1984 and then launched in Europe with differences in the information services provided from country to country. With its in Europe and many countries outside data burst. An intermediate stage in introduction in the United States as from Europe should be completed by the turn the overall development is the analog 1994 and in many other non-European of the millennium. PALplus method, which is compatible countries RDS became worldwide stan- with PAL but specified for the new dard. Television aspect ratio 16:9. Digitization in the picture area began in the TV studio with The compact disc, launched by Sony The international TV standards PAL, the specification of the 4:2:2 component and Philips in 1985, was one of the SECAM and NTSC have practically standard (CCIR Rec. 601). As for trans- events triggering off the revolution in been untouched up to the present day mission from the studio to the viewer, sound broadcasting towards digital as far as the picture information is con- the future lies no doubt in digital video techniques. The CD created quality cerned. The developments made mainly broadcasting (DVB), which is ready to very close to that of a concert hall and had a program-supplementary charac- be implemented in the media of satel- added a further benefit in terms of sim- ter. Over the past ten years innovations lite, cable and terrestrial transmissions. ple and robust handling. The CD was were achieved on the basis of the giv- Toward the end of 1995, the European of course a challenge to sound broad- en redundancy in the time- and frequen- DVB project concluded the specification casting to provide the same quality and cy-related representation of the signal. of channel coding and modulation for performance features. This is when the In the mid-70s, for example, the teletext broadband digital TV channels. demand for terrestrial propagation of system was launched in different ver- digital audio broadcasts for mobile re- sions throughout Europe. Another digi- With DVB the digital baseband signal ception came up. From 1988 to 1992 tal TV service was added in the early is sent in compressed form according to the specification committee EUREKA 80s: the video program system (VPS) the MPEG2 standard (Moving Picture 147 defined digital sound transmission based on the TV data line ensuring pro- Experts Group). Depending on the with DAB (digital audio broadcasting) gram-synchronous recording by video compression factor there are different as a pure audio transmission system for recorders even in the event of program quality levels and data rates: LDTV (lim- mobile reception up to a vehicle speed delays. ited definition TV with 1 to 1.5 Mbit/s), of 160 km/h. Further applications SDTV (standard definition with 4 to covered by keywords such as “value- The change in TV picture transmission 6 Mbit/s), EDTV (enhanced definition added service” and “data service” came about in the mid-80s in Europe with 11 Mbit/s), HDTV (high definition were added. The DAB channel can be with the compatible MAC (multiplex with 30 Mbit/s). The net data capacity considered as transparent point-to-area analog component) line. D2MAC is a of one or more video and/or audio coverage for mobile reception and combination of separately transmitted, sources is transmitted within a multiplex with an effective data capacity of about compressed luminance and chromi- signal (transport stream, TS). DVB thus 1.2 Mbit/s. The introduction of DAB nance signals and a digital sound and follows the container principle with

News from Rohde & Schwarz Number 152 (1996/III) 57 Final article

such as MMDS (multichannel microwave distribution system), BISDN (broadband ISDN) or IBCN (integrated broadband communications network) or ADSL (asymmetrical digital subscriber line) are being developed and FIG 2 CATV configuration made accessible for multimedia trans- with QAM modulator mission. The interactivity potential is for intelligent broad- taken account of by an initially narrowband communication band back channel in the transmission systems [2] medium. transparent transmission channels. Er- mous for the convergence of the appli- The new multimedia world needs ac- ror protection for the transport stream is cations. ceptance by the consumers of course. adapted to the physical medium by Therefore it must be introduced step means of channel coding. The stipulat- In this context the foremost feature is the by step. In the first step compatibility ed modulation modes are QPSK (quad- combination of devices in the home between the existing TV receiver and rature phase shift keying) for satellite such as desktop workstations, CD video, the new digital transmission technology transmissions, 64QAM (quadrature digital video cassettes, CD players will be established with the aid of the amplitude modulation) for cable and and/or video cameras to form a kind of set-top box or the integrated receiver OFDM (orthogonal frequency division local area network (LAN). The second decoder (IRD). The set-top box has and multiplexing) for terrestrial broad- feature, which is interactivity via a functions similar to a computer to casting. For the latter, the modulator in data channel, can nowadays already establish the connections between the the terrestrial transmitter is followed by be implemented via digital telecom- digital broadcasting medium and the high-power amplifiers for the OFDM munication media such as GSM/PCN conventional TV receiver, the PC and modulation signal. These amplifiers are (global system for mobile communi- the telecommunications network, ie it is preferably of solid-state design and cations/personal communication net- a multimedia switching center. Broad- feature high linearity. work), ISDN (integrated services digital band transmission channels for multi- network) or Internet. Multimedia also media are specified in the form of DAB Multimedia implies a third feature, ie the broad- and DVB-S (satellite), DVB-C (cable) band transmission of moving pictures, and DVB-T (terrestrial) and their imple- Parallel to the revolutionary develop- sound signals and data services. The ments in the field of broadcasting, a classic broadcasting media using ter- union of the worlds of audio/video, restrial, satellite and cable transmis- telecommunication and computer was sions with SMATV (satellite master an- FIG 3 MPEG2 Generator DVG and Measure- started up last year for the consumer tenna TV) are utilized in the introducto- ment Decoder DVMD for DVB transport data sector (FIG 1). “Multimedia” is synony- ry phase. Further broadcasting media streams [3]

58 News from Rohde & Schwarz Number 152 (1996/III) Final article

mentation is already in progress in hyperband originally intended for be continued in the new digital technol- some European countries. D2MAC transmission is now available. ogy. We offer solutions in the form of In addition, interactive capability in the units, systems, turnkey single-frequency The new digital transmission technol- form of the back channel is given in networks, broadband communication ogies bring decisive benefits for the the range from 5 to 20 MHz. German systems as well as remotely controlled consumer: Telekom will have equipped its cable test and monitoring equipment for net- • low-cost receivers in a multimedia headends with modern digital systems work operators. With its key products environment, for 64QAM modulation, frequency for digital broadcasting system and test • good picture quality (SDTV) to high conversion and distribution by the end equipment (FIG 3 and 4), Rohde & definition TV, of 1996 and relies on well-proven Schwarz is right now best prepared to • large number of programs, Rohde & Schwarz technology (FIG 2). live up to its reputation as one of the • portable reception of terrestrial TV The next step will be the implementation world’s leading DAB/DVB suppliers programs, as well as for the network operator: • economical utilization of the resource frequency, • flexible use of the transmission channel, • reduction of investment, energy and service costs.

Therefore the implementation of the DAB and DVB standards is being strongly pushed ahead as shown by the following examples.

Implementation of DAB began in 1995 with the Bavarian pilot project as the first project worldwide using single- frequency operation on this scale. In addition to the channel-12 transmitters including DAB coder/decoder, Rohde & Schwarz supplied the complete infra- FIG 4 TV Test Receiver EFA with QAM measure- and to master the quantum leap into the structure with audio baseband coding ment functions for DVB-C [4] digital future of broadcasting and multi- (MUSIC) and DAB multiplexer as well media communication. as program distribution via satellite. Paul Dambacher German Telekom recently started com- of intelligent interactive headends with missioning 60 DAB L-band transmitters servers, billing and network monitoring for a national coverage network with as well as connection to public data Rohde & Schwarz as the main supplier. networks.

Digital video broadcasting was start- Terrestrial digital video broadcasting REFERENCES ed in mid-1996 via the SES-ASTRA will be started in the UK in 1997 with [1] Reimers, U.: Digitale Fernsehtechnik, Daten- satellite 1F, which was launched to its the programs of NTL and BBC. In kompression und Übertragung für DVB. orbital position 19.2° east from the Germany, DVB-T pilot projects in Berlin, Springer Verlag (1995) Baikonur (Kazakhstan) cosmodrome in Cologne and Munich are now in the [2] Schönberger, P.; Sturm, P.; Scheide, R.: CATV Headend System CT200 – CATV signal pro- April 1996. Another two ASTRA digi- planning stage. Since 1995, a DVB-T cessing intelligent, compact, versatile. News tal satellites are planned for 1997. transmitter from Rohde & Schwarz from Rohde & Schwarz (1995), No. 148, Eutelsat, too, will take up digital tele- has been tested by the Swiss PTT. This pp 23 – 25 vision in 1997 via the Hot Bird satellites transmitter can be switched over to the [3] Fischbacher, M.; Weigold, H.: MPEG2 Gen- 4 and 5. emission of PAL signals for coverage erator DVG and MPEG2 Measurement De- coder DVMD – Test equipment for digital TV comparisons. in line with MPEG2. In this issue, pp 20 – 23 Broadband cable technology is [4] Balz, C.; Polz, E.; Fischer, W.: TV Test Receiv- optimally prepared for digital television The particular strength of Rohde & er Family EFA – Top fit for digital television. with interactive communication: the Schwarz in analog broadcasting will In this issue, pp 17 –19

News from Rohde & Schwarz Number 152 (1996/III) 59 21 . 2250 . 7 2 · PD 75 5 1 News from Rohde & Schwarz

ROHDE& SCHWARZ GmbH & Co. KG · Mühldorfstraße 15 · D-81671 München P. O. B. 8014 69 · D-81614 München · Tel. (+49 89) 41 29-0 · Fax (+49 89) 41 29-21 64