Agilent Technologies and Communications: Six Decades of Measurement Contributions Contents

Agilent Technologies March 2000 Issue 20 U.S. Edition

3 Agilent Technologies and Communications: Six Decades of Measurement Contributions

4 The early days

5 Cable multiplex communications

6 Pulse-coded modulation

7 Logic test and the digital revolution

8 Datacom testing

9 Digital transmission testers

10 Broadband communications

11 Terrestrial microwave communications

13 Satellite communications

15 Mobile-radio communications

16 Modern wireless communications

17 LMDS in the last mile

18 Military communications

21 Environmental testing

22 Broadcast communications

24 Cable television

25 Lightwave communications

27 RF and microwave component design

30 General communications applications

31 General technology contributions

33 Superstars

36 Agilent’s products today

2 Agilent Technologies and communications Agilent Technologies and Communications: Six Decades of Measurement Contributions

It can be reasonably argued that Agilent Technologies—which incor- porates the former test and measurement sector of Hewlett-Packard Company—has been making measurement contributions to the communications industry ever since Dave Packard and Bill Hewlett assembled their first product, an audio oscillator, in 1939 in a Palo Alto, California, garage.

That product was the HP 200A audio oscillator, and its most famous sale was to the Walt Disney Company for use in making the movie Fantasia. But it also was used widely in the design of transmission components, including amplifiers, transformers, and filters, for the twisted-pair wireline telephony systems of that era.

With the outbreak of World War II, communications technology became the focus of intense R&D efforts as Bill Hewlett and Dave Packard. a strategy for winning the war. In this document, we’ll take a The results of those efforts revolu- journey through the development of tionized the world. Agilent, through 20th century communications and its HP heritage, has played a signifi- Agilent’s test and measurement cant and continuing role in the contributions. Although we discuss communications revolution, making technologies up to the end of the hundreds of test and measurement century, our focus is on the histori- contributions in nearly every sector cal achievements rather than pre- of the industry. sent-day trends.

3 The early days

In the earliest analog telephone Proceedings of technology, open-wire telephone 1939, the oscilla- lines dominated the outside plant. tor caught the Then came twisted-pair wires attention of the bundled into underground cables. Chief Engineer at In the U.S., these formed the back- Walt Disney bone of the communications system Company, who well into the 1940s. Some of us still needed a number have images of telephone poles of audio sources along country roads, with multiple for sound effects cross-arms and dozens of green-glass in Fantasia. The insulators supporting open wires competing oscilla- that went on for hundreds of miles. tor of the day was The 200A audio oscillator was Hewlett-Packard’s first commercial success. The technology of communicating a “beat-frequency” in those days was heroic, and it oscillator that cost seemed that the only way to let ten times as much. Disney’s Chief a common 7.5 watt lamp bulb—into more people communicate was Engineer bought eight of the the cathode circuit of the oscillator through brute force design, by HP models. vacuum tube. adding more wires over head or more cables under ground. The clever circuitry of the 200A With the introduction of the 300A audio oscillator was the subject audio analyzer (ca. 1941), engineers Hewlett-Packard’s original audio of Bill Hewlett’s Electronic could analyze signal distortion in oscillator, used with the 400A Engineering thesis at Stanford the audio components used in tele- vacuum tube voltmeter (ca. 1941) University. In a slim document of phony. Testing was still in its early that boasted a 1 megacycle band- less than 20 pages, he presented days. One HP engineer recalled as width, allowed the characterization a circuitry that was the essence of a college student being assigned to of frequency-response parameters of simplicity. It used a tunable resis- arrive at the engineering lab early a variety of system components, tance-capacitance network to pro- in the morning to turn on the including amplifiers, transformers, vide the 180-degree feedback phase instrument so that its vacuum-tube filters, line-loading components, shift needed for oscillation; an inex- drift would stabilize for lab use later and switches. One of Hewlett and pensive tunable radio capacitor for in the day. Packard’s objectives was to provide the two ganged capacitors; switched “inexpensive quality,” and the audio resistors to achieve the tuning In the telecommunications infra- oscillator was a good example. range; and an innovative amplitude- structure, the underground wire-pair Originally advertised for $71.50 in stabilizing function made by insert- plant served local distribution needs the Institute of Radio Engineer’s ing a positive-coefficient resistance— for decades, and HP continued to introduce new test products to improve its efficiency. In 1959, the 302A wave analyzer (20 Hz – 50 kHz) brought powerful low-frequency (LF) spectrum analysis to component and signal design. This analyzer was just the second HP product with an all-transistor design—the first being 1958’s 721A power supply.

In 1962, HP introduced the 3550A portable frequency response test set for installation qualification and troubleshooting of twisted pair cables. This product was followed by the 3555A telephone test set. These instruments were called Transmission Measuring Sets (TMS), distinguishing them from the famil- The 3550A frequency response test set could qualify and troubleshoot twisted-pair cables. iar Transmission Impairment Measuring Sets (TIMS) of today.

4 Agilent Technologies and communications Cable multiplex communications

As the 1940s’ wireline technology the 3745A selective level measuring reached its limits, particularly in the set (ca. 1975) offered system engi- underground cabling of twisted pairs neers following the CCITT-standards of wires that served urban areas, precise measurements of FDM tele- new technology was needed. One phone equipment with as many as answer was to exploit the broadband 3600 channels. This 25 MHz super- carrying capacity of coaxial cable, heterodyne receiver measured down and as a result, AT&T’s research labs as low as -125 dBm with synthesizer rolled out their first cable multiplex precision. In 1978, the 90 MHz systems, the L-1 through L-5. 3747A selective level measuring set was targeted at the new genera- Cable multiplexing grouped dozens tion of 60 MHz cable that handled of individual telephone conversations 13,000 channels. together using a technology called frequency domain multiplex (FDM). The 312A wave analyzer and 313A tracking The 3586A/B/C selective level Each conversation occupied 3 kHz of oscillator were diagnostic tools for multi- meters followed in 1980 for FDM channel width and was spaced 1 kHz plexed cable. applications to 32.5 MHz. And com- from its neighbors. Twelve audio chan- panion 3336A/B/C synthesizer/level nels were single-sideband-modulated As cable multiplex technology generators teamed with the selective into a group; five groups were com- progressed, AT&T added more and level meter products to characterize bined to form a super group; and ten broader channels to their cables, transmission components for super groups were combined into a pushing the technology to its limits both North American and CCITT master group. The key to this technol- by installing an underground cable signal formats. ogy was perfect linearity in the ampli- system across the U.S. from New fication and all other circuitry. Slight York to Los Angeles. Cable systems non-linearities showed up as inter- also began to provide the broadband modulation, which resulted in degrad- links required between the 7000 ed background noise and cross-talk. telephone central offices around the country. The AT&T L-systems Amplitude flatness across the many ultimately reached 65 MHz per cable. multiplexed channels was measured over the 1.5 MHz band by HP’s 310A The 312A wave analyzer (ca. 1966) wave analyzer (ca. 1963). A wave was a powerful diagnostic tool for analyzer is essentially a calibrated multiplexed cable because it cov- superheterodyne receiver, and this ered the 18 MHz range, was fully one featured a selectable output programmable, and featured many bandwidth, which allowed the detect- user improvements such as automatic ed audio modulation to be measured. frequency control. Outside the U.S.,

5 Pulse-coded modulation

In a real sense, most of the spectac- Now AT&T developed their T-systems, HP’s digital instrumentation devel- ular communication technologies of with a hierarchy of data rates up to oped across a broad front to help the late 20th century were based on T-4 (274 Mbit/s), running over coaxial speed the digital revolution. The a simple analog-to-digital concept. cable. Similar standards were devel- 4940A transmission impairment In the 1960s, when it became eco- oped outside the U.S., where the measuring set (ca. 1974) met an nomically and technically feasible CCITT hierarchy packed 30 voice urgent need as telephone companies to digitize analog waveforms on a channels into a 2.048 Mbit stream. began widespread installation of massive scale, everything in com- data modems to send data over munications got better. Using a The digital data streams revolution- voice circuits. This TIMS was well-known sampling theory and an ized telephone voice quality. As designed to measure the analog 8-bit digital word to express ampli- transmission distances had parameters of wire lines that affect tude samples taken at 8 kHz, each increased, the analog signals were data transmission, and it was used 3 kHz audio voice bandwidth was subject to gradually increasing widely as a verification tool for line converted into a 64 kb/s digital data noise. When amplifiers were used to quality and performance testing. stream. Twenty-four streams were build up the analog signal for anoth- The 3770A amplitude/delay analyzer interleaved into the 1.544 Mbit/s er cable hop, they added noise in made similar measurements for signal called T-1 in the U.S. This each hop. In contrast, digital pulse CCITT standards. modulation format was described regeneration sent brand new pulses as time-division multiplex (TDM). into the next cable hop, eliminating the audio noise and distortion that Amazingly, this T-1 signal could be came with distance. So the low noise transmitted on those same ordinary and clarity we often attribute to twisted pairs, which vastly increased fiber optics in reality began with the capacity without laying a single foot of first digital technology of the 1960s. additional cabling beneath the streets.

6 Agilent Technologies and communications Logic test and the digital revolution

It wasn’t long after time-divi- The later 71603/612A Gb/s sion multiplexing invaded the testers analyzed data-error analog domain that computer- performance all the way to to-computer data communica- 12 Gb/s, and are used today tions arrived with a major by many laboratories around demand for transmission the world for developing bandwidth. The term datacom high-speed optical transmis- first came into use to define sion systems. such computer-data traffic. PCM technology became the In 1980, with the introduc- modulation format of choice tion of the 64000-series logic for serial data on cable and for development systems, digital radio in terrestrial and design engineers began to satellite applications. Digital take control of the burgeon- techniques began to influence ing field of complex logic every facet of communications design for microprocessors. technology. And underpinning Then came tools to simulate this new datacom technology VLSI circuit design and were logic circuits. graphical aids to provide better insight into layout Logic designers looked for processes. diagnostic measuring tools to An emulator for the Motorola 146805G2 microcomputer added new help characterize their new capability to HP’s 64000 logic development system. More recently, HP/Agilent digital circuits. HP, with its logic analysis and emulation large engineering departments, Next the 1600L logic state analyzer tools are almost too numerous to quickly became a pioneer—not only (ca. 1974) was built into an oscillo- list, ranging from PC-hosted to high- by developing new techniques, but scope configuration that displayed ly integrated units with basic timing by having an immediate forum in 16 consecutive logic states of 12-bit analysis to cross-domain measure- which to try out bright new ideas. words. This instrument had complex ments. Hardware solutions are inte- Bill Hewlett coined the term “next- triggering modes for capturing specif- grated with software solutions for bench-syndrome” to describe how a ic sequences of pulses from ICs and microprocessor and bus support. product idea could gain quick accep- ROMs. The 1645A data error analyzer tance when neighboring engineers that followed analyzed bit error rates HP/Agilent semiconductor test immediately asked to borrow the and other transmission parameters. systems have also contributed in this inventor’s new measurement tool. area, by providing fast and compre- The 1600A logic state analyzer hensive characterization for VLSI, The concepts of logic test started (ca. 1975) was able to analyze 32 digital, memory/logic, mixed-signal small. The 10525A logic probe data streams at 20 MHz. Its innova- RF, and semiconductor parametric (ca. 1969) traced logic states in TTL tive “data-map” display could locate applications. These systems use pow- and DTL integrated circuits with a digital words on a two-dimensional erful software and modeling routines simple probe tip and associated LED map, which also displayed a vector to speed the design iterations of indicator. The 10528A logic clip for tracing the digital direction from those chip engineers in the communi- (ca. 1970) and 10529A logic com- word to word. An associated multi- cations industry who must deal parator were little, handheld diag- channel word generator, the 8016A with rapid deployment and fast nostic tools that simply clipped onto word generator, supplied 32-bit turnaround of design cycles. IC packages and gave the user imme- words at 50 MHz. Such instruments diate feedback through an array of were invaluable in the fast-moving LED lights. world of microprocessor development.

Complete instruments were soon on In 1973, HP introduced one of the the way. The 5000A logic analyzer earliest high-speed bit-error-rate (ca. 1973) featured a two-line dis- testers, consisting of the 3760A data play of 32 LEDs, each of which cap- generator and the 3761A error detec- tured a pulse stream and displayed tor. By stimulating circuits under the pulse sequence. The instrument test using pseudo-random pulse was a sort of specialized oscilloscope sequences selectable from 7- to 32K- with sophisticated pulse condition- bit lengths, the system operated with ing and capture processes. bit rates up to 150 Mb/s. 7 Datacom testing

Over the years, an important general- Protocol analysis first purpose instrument for digital appeared about 1984, communications has been the pulse with the 4951/53/55A generator. HP introduced the 8015 protocol analyzers. Data and 8011A pulse generators in 1973 communication was get- and 1974. These were followed by the ting to be serious busi- 8016A word generator of 1975, which ness, and these instru- supplied 8 simultaneous 32-bit words ments were designed to at 50 MHz for communications appli- assist digital network cations. In the following decades, HP designers, data centers, introduced ever-higher data rates and field maintenance and complex pulse formats for mea- organizations. They surement and diagnostic applica- were powerful tions. On datacom R&D benches and machines, covering the production lines, pulse generators major protocols of the have served with the same impor- day: X.25, HDLC, BSC, tance and ubiquity as oscilloscopes. SDLC, SNA, DDCMP, X.21, and CCITT No. 7. After system engineers tested the serial They featured highly data transmission—to ensure that pulse flexible triggering and The portable Internet Advisor (now Agilent Advisor) introduced levels, data rates, and backup logic speeds to 72 kb/s. internetworking test capability for LAN, WAN, and ATM networks. techniques such as parity and redun- dancy bits were getting to their desti- The introduction of the 4972A LAN family includes the company’s first nations—they turned to the next-higher protocol analyzer in 1989 targeted software analyzer that runs on a level of moving messages, the protocol Ethernet and StarLAN networks, notebook PC. level. There, they needed to make sure and the 4974S/A MAP protocol that the handshake, start-message, end analyzer supported IEEE 802.4, The emergence in the late 1980s of message, and all transmission “rules” 802.2, ISO, ACSE, FTAM, and more. the CCITT No. 7 Common Channel took place in the right order. HP was able to contribute much to Signaling protocol (SS7) revolution- datacom testing because ized the control of message switch- it was itself a large ing. Earlier strategies called for user of the technolo- message routing information to be gies. Agilent today car- sent down the same channel as the ries on that tradition. voice or data, leading to fraudulent exploitation of the network by so- A typical example called “blue boxes,” which could of a product family simulate switching-control signals. today is the Agilent By moving all message-routing Advisor, a modular instructions onto a separate, protocol analyzer that dedicated channel, system opera- provides powerful tors could centralize operational diagnostic and analy- control of their networks. From this sis functions for came a powerful ability to monitor testing multiple data and measure all kinds of signaling technologies such as system parameters. The 37900A sig- LAN, WAN, ATM, and naling test set (ca. 1989) helped emerging voice over install and maintain these signaling IP (VoIP) and fax systems. And it led directly to the protocols. Agilent’s acceSS7 network monitoring system LAN Analyzer prod- (described under Superstars) and uct family today pro- the current signaling advisor test vides hardware and sets, which non-intrusively monitor software to manage the SS7 network, displaying real-time and maintain analysis of signaling data, loading 10/100/1000 Ethernet levels, and error rates, and provid- LANs and 4/16 Token ing statistical reports of message Ring networks. The types and more. The 37900A signaling test set sped troubleshooting of SS7 networks.

8 Agilent Technologies and communications Digital transmission testers

The fundamental measure of performance or quality in digital systems is the probability of any transmitted bit being received in error. This is the purpose of digital pattern generators and error detectors, often referred to as bit error rate testers or BERTs. HP’s long tradition of offering the highest performing instruments in this class is carried on by Agilent today.

The 86130A 3.6 Gb/s BitAlyzer is a serial BER tester with power error analysis capability and a friendly user interface. As described earlier, the 71612A error performance analyzer addresses digital testing to 12 Gb/s. The ParBERT 81250 parallel BER tester generates pseudo random word sequences (PRWS) and standard PRBS on parallel lines up to 2.67 Gb/s, Agilent ‘s tablet-based Service Advisor, part of the Telecom Toolkit, reflects the industry’s making it ideal for multiplexer and increasing desire for modular, handheld, multi-format test instruments. demultiplexer testing. The E7580A ProBER is a handheld tester for 2 Mb/s Today the Agilent OmniBER family With the acquisition of CERJAC, and 64 kb/s digital-circuit testing. of communications performance a manufacturer of portable telecom- analyzers offers a range of one-box, munications test equipment, HP Beginning in the 1990s, HP’s SONET field-portable testers for installation, expanded the breadth of its field- and SDH analyzers performed maintenance, commissioning, and service test products in the early accurate, reliable tests on network manufacture of transport networks 1990s. Portable and handheld equipment and transmission and network equipment. Optical instruments for field-service testing services. Portable units were used 1310nm and 1550nm interfaces included the CERJAC 156ATM test to troubleshoot SONET and SDH are supported, as well as electrical set as well as products for T-carrier equipment at rates up to 2.5 Mb/s. interfaces at all the commonly used testing. Those product lines have Modular, VXI-based instrumentation telecom rates. The testers can be evolved to the Agilent Telecom could be easily integrated into R&D, configured to include DSn, PDH, Toolkit, which includes the modular, production-line, or ATE systems SDH, SONET, ATM, DWDM, and flexible Service Advisor portable for testing both SONET and SDH jitter generation and measurement. test tablet platform with a growing standards up to 10 Gb/s. They perform non-instrusive moni- family of plug-in modules for ADSL, toring of live traffic or test network HDSL, ATM, SONET, SDH, PDH, and protection switching mechanisms, TDR testing; the portable T1 and out-of-service BER measurements, E1 Advisor families, and the aurora and other important parametric tests. series of handheld testers for DSL, ISDN, frame relay, and ATM testers. The Agilent SpectralBER test solutions offer flexible and versatile SDH/SONET functional test capability from 155 Mb/s to 10 Gb/s.

9 Broadband communications

The early 1990s saw the rise of broadband communications, which has been spurred by the phenome- nal growth of the Internet and the “fast packet” revolution. One of the first robust technologies developed to deliver high bandwidth services was asynchronous transfer mode (ATM). HP was a leader in developing ATM test technology, and the introduction of the Broadband Series Test System (BSTS) in 1994 quickly became the industry standard for ATM testing. Today the BSTS continues to offer the industry’s most comprehensive solution for ATM Forum traffic management compliance and for ATM signaling test. With the evolution of wire-speed switch-routers from enterprise networks to carrier data networks, the BSTS has expanded to include The Broadband Series Test System has been the industry’s platform of choice for testing ATM new standards such as packet-over- technology since 1994. SONET (POS). As ATM is a key technology for multiplexing voice, data, and signaling between fixed network elements, the BSTS added third-generation (3G) wireless test capability in 1999 for testing new wireless data technology.

10 Agilent Technologies and communications Terrestrial microwave communications

In the early 1950s, AT&T The 3792A microwave link exploited the earlier, analyzer (ca. 1975) and wartime development later the 3711/12A IF/BB of microwave signal sources transmitter/receiver (ca. such as klystrons and began 1979) were able to handle installing a cross-country systems with intermediate radio link system known frequencies of 140 MHz, as the TD system, which designed for 2700 telephone operated in the 3.7 to channels. Such dense multi- 4.2 GHz band. A 30-MHz plexing required precise bandwidth was devoted to The 3708A gave engineers an accurate way to assess the performance of control of distortions such each of the system’s FM- microwave radio and satellite modem systems. as AM-to-PM conversions modulated channels, which and amplitude linearity carried 1800 (later 2700) and group delay. conversations. As the technology progressed, one of the key instruments that measured After AT&T’s microwave link system Soon microwave antenna towers and verified amplitude flatness had been in use for many years, began appearing on the flatlands of and tight group delay on system the U.S. Federal Communications northern Indiana and the mountain- components was the 3702B/3710A Commission (FCC) allowed AT&T tops of Nevada and California. The microwave link analyzer (ca. 1972). to relax earlier rules requiring 2 system was extremely complex for By presenting the phase deviations of the 12 channels to be reserved that time, since the coast-to-coast from linearity on an oscilloscope, for “hot-standby.” AT&T instantly span required perhaps 150 radio the analyzer allowed designers and increased their channel capacity, line-of-sight hops. Because the system technicians to tune components and the only penalty was the need was all analog, all its links operated and antennas into specification. to install an HP 83001A agile micro- in series, thereby placing specifica- The 3730A down converter and the wave radio (ca. 1974) at each repeater tions of unprecedented tightness on 8605A microwave upconverter were station. The 83001A could be tuned amplifier flatness, group delay, and used to translate the analyzer’s to any of the operational channels, intermodulation. measurement capability into the so it could replace an out-of-service microwave carrier bands. channel during maintenance. Microwave communication links moved into north-south systems, and one well-known link from Chicago to St. Louis became the founding asset of Microwave Communication Inc. (later MCI Corp. and now MCI WorldCom), the first direct competitor to industry-giant AT&T. Terrestrial microwave technology was the first technical solution for transmitting broadband signals nationwide, and it also helped launch today’s network television.

To help microwave communication companies install and maintain their microwave radio links, HP developed the 623/24A microwave test sets (ca. 1952), which offered three functions: supplied test power with calibrated output to -100 dBm for testing the system receiver, power measurement of the system transmitter, and frequency measurement of the system transmitter. The test sets were available for the 4, 6, and later 11-GHz communications bands.

11 Since much of the circuitry of A companion analysis tool, the Testing was essential for terrestrial microwave radio is analog, new 8980A vector analyzer, was able to radio links, which experience multi- diagnostic equipment was needed display high-speed vector diagrams, path fading due to signal reflections when digital modulation formats magnitude-phase versus time, and from mountain and ground effects. began to invade microwave radio constellation diagrams. It also pre- The 11758T digital radio test system applications. The 3709A constella- sented time-domain eye diagrams of (ca. 1990) combined measurement tion display (ca. 1987) provided complex, high-data-rate modulations of eight different test parameters, valuable insights into commonly intended for terrestrial and satellite so that design engineers could verify used modulation formats such as applications. The first users were that their signal equalizers mini- QPSK, 9QPR, 16QAM, and 64QAM. startled to see a 3-dimensional mized fading, and so that installa- The companion 3708A noise and image of a digitally modulated data tion engineers could meet FCC interference test set helped engi- stream that looked like a spiral qualification requirements. The neers quantify the spring extending out of the CRT. system included a microwave spec- all-important relationship between trum analyzer to create a powerful signal-to-noise and bit-error-rate. The 11736A I/Q Tutor (ca. 1986) was test instrument. a clever little computer-training In 1987, HP’s signal generators model that taught the fundamentals began to feature the complex digital of digital microwave radio using a modulation formats that were being PC. The I/Q Tutor modeled a system used by communication system block diagram from the audio on one designers. The 8780A vector signal end to the audio on the other. At generator provided 150 Mb/s data each of the diagram’s stages—analog- rates for digital phase modulations to-digital converter, map to I/Q, such as BPSK, QPSK, and 16- and filtering, mix to IF, upconvert to RF, 64-QAM at carrier frequencies up to power amplifier to antenna, and 3 GHz. This generator was the first back again to audio—the model to accept data lines, rather than scrolled down to typical waveforms analog signals, for modulation. and eye diagrams, allowing users to set filter factors, data rates, modulation types, and signal-to-noise ratios.

12 Agilent Technologies and communications Satellite communications

In the 1960s, technical visionaries plex signal paths inside the satellite. to the 608F. By designing a varactor saw the potential for using satellites The 8540A was based on the 8410A into the oscillator circuit, the 8708A to carry massive amounts of commu- vector network analyzer (VAN), frequency synchronizer (ca. 1966), nication traffic all around the globe. which we’ll describe later. with its crystal-controlled, phase- The first commercial applications locked source, eliminated the drift were made by the Comsat Signal-switching matrix switches and cleaned up the phase noise. Corporation, a U.S. business-and- routed signals to and from the satel- government alliance that funded the lite under test, and provided power- The 8660A/B synthesized signal gen- early technology. Designers had to ful test routines and complex signal erator (ca.1971) was one of the first manage complex multiplexing tech- data processing. Error correction examples of totally integrated, indi- nology and achieve reliability of accounted for cable losses and signal rect signal synthesis. The instrument their systems in the harsh environ- degradation. Signal-stability perfor- had plug-ins for both modulation ment of space. Since repair and ser- mance had been a key ingredient of and output control, and it provided vice to an in-orbit bird was impossi- satellite payload design from the 0.01 to 110 MHz, and later 2600 MHz, ble, the designers had to incorporate beginning. Thus, synthesizer-stabi- with excellent signal performance. multi-path and redundant circuits lized generators became the technolo- and components. gy of choice for transceiver designers. In the 1960s, the era of the U.S. Apollo Space Program, which suc- These “switchboards in the sky” In orbit, satellites needed to have cessfully put men on the moon, com- were so complex that they ushered their channels loaded properly, munications technology did not have in a new era of automated test because the transponders were lin- components with the integrated cir- instrumentation. HP was there with ear systems. Signals needed to be cuits and LSI and VLSI that we know the 8540A automatic network ana- distributed evenly so that peak today. Yet a system such as the inte- lyzer (circa 1969). Controlled by the power wouldn’t be distorted and grated S-band communications link 2116A instrumentation computer, cause intermodulation effects. The used in the big Saturn rockets pro- the system enabled assembly and all- 8580A automatic spectrum analyzer duced magnificent results. Here was up-around checkout tests of the com- (ca. 1971) was perfect for such a job. a system in the 2350 MHz band that Consisting of an carried the entire telemetry traffic HP 2116A com- used to monitor hundreds of parame- puter and an ters in the propulsion systems and 8552A or 8553A- the operational subsystems; the voice type spectrum traffic to and from the crew; medical analyzer, which telemetry; and finally, the most excit- was modified for ing communications innovation of computer control all, the video cameras. These cam- and programmed eras put us earthbound viewers right for long-term sig- in the cockpit—and out on the lunar nal monitoring, rover, the little “golf cart” that car- the system could ried its own camera onto the moon’s gather data con- surface and brought the world along tinuously and with it. With a fixed camera left at aid in managing the landing site, we were able to see the signal traffic the final liftoff from the moon, which in satellite rippled the American flag standing communications. on its pole, a testament of that great venture. HP’s signal generators and Phase-locking spectrum analyzers served in the technology of the design and test of those incredible mid-1960s led HP communications systems. to develop new applications for In later decades, NASA ventured high-stability sig- into interplanetary scientific travel. nals by phase- Unmanned spacecraft now could use locking the vener- exquisite integrated circuits for pow- able 608D VHF erful functional control and mea- The 8580A automatic spectrum analyzer gathered data for managing signal generator surement of the far solar planets. satellite communications. and converting it Cameras and scientific payloads

13 gathered massive amounts of data from our solar neighbors and advanced the world’s knowledge of the creation of the universe. The sophisticated communications links and the massive earth antennas such as the Goldstone dish in the Mojave Desert testified to an ongo- ing tradition of innovation. How far technology had advanced is illustrat- ed by the fact that the 300 foot diameter Goldstone receiver could obtain useful data from received signals at levels as low as one pho- ton per square meter per second. The 8660B signal generator is an early example of the use of totally integrated, indirect signal synthesis. Indirect frequency synthesis became the main feature of future synthesized generators and sweep- In the 1990s, the 83731/32B signal Site-surveillance applications ers. In 1977, the 8672A microwave sources upgraded the performance became important when satellite signal generator delivered 2 to 18 of AM, FM, and pulse modulation ground stations were first planned. GHz signals with 15 ms programma- with excellent phase noise and har- Because those systems had to ble carrier agility. This instrument monics to 20 GHz. Today, Agilent’s receive tiny signals from space, became the core of a wide variety of 83550A millimeter-wave sources earthbound interference could not automated satellite test systems. supply signal power in multiple be tolerated. The 8582A automatic waveguide bands from 26 to 110 GHz. spectrum analyzer (ca. 1980) was The 8673A microwave signal genera- They are increasingly useful as mili- ideal for testing these systems. tor (ca. 1983) produced 26 GHz test tary, satellite, and commercial appli- Outfitted with broadband antennas, signals. It was followed by a family cations move above the traditional this analyzer could sit in a mobile of synthesized microwave sweepers microwave communications bands. van for days and weeks, monitoring that could serve as highly stable the local signals and other man- sources for network analyzers, which made electromagnetic interference required error corrections at specif- and preparing statistical-occurrence ic frequencies. In order to speed data packages. network measurements, these synthesized sweepers used a modified sweep called “lock-and-roll.” Now two categories of product were now available: synthesized signal generators that could modulate signals and sweep, and lock-and-roll sweepers that could be synthesized.

14 Agilent Technologies and communications Mobile-radio communications

By the time WWII began, By adding signal-separation mobile radio communications direction couplers or RF technology had already pro- bridges, the meter could be gressed and was typified by transformed into a sweeping FM-modulated radio links impedance meter. This two- that served the public and channel concept led directly some commercial sectors. to development of the block- The transceivers used for buster 18 GHz 8410A net- police, fire, and forestry work analyzer, introduced applications were bulky and in 1968. (We cover this in the cumbersome, but still effec- Superstars section.) tive. Transceiver circuitry employed vacuum tubes, About 1977, HP began to which depended on B+ sup- focus on all-round testing of ply voltages of perhaps 125 mobile transceivers. By com- Vdc, obtained through use of bining a desktop computer, a vibrating contact that Modular printed circuit boards could be inserted and removed signal generator, counter, chopped the 6 Vdc auto bat- from the 8405A vector voltmeter for RF performance testing. power meter, various modu- tery supply into a step-up lation sources, power sup- transformer and a high-voltage-recti- A variety of signal generators served plies, and switching, the 8950A fier vacuum tube. the mobile FM market, including sev- transceiver test system was born. eral models acquired by acquisition It provided all the signal and mea- Exploiting WWII tactical radio tech- of the Boonton Radio Company in surement capability necessary to nology, postwar applications in 1960. The 202H (Boonton) FM signal completely characterize an FM mobile telephony grew rapidly, par- generator was widely used in pro- mobile transceiver. Affectionately ticularly after the introduction of the duction and service facilities. Later called “Bigfoot,” it began to define transistor in 1948. Low-voltage and AM-FM generators such as the 8654B testing strategies for the rapidly rugged, transistorized devices quick- signal generator (ca. 1976) and the growing manufacture of huge quanti- ly replaced the bulky vacuum tube 8642A/B signal generator (ca. 1985) ties of mobile radios. technology. However, frequency- featured expanded precision, capa- spectrum assignments severely limit- bility, and programmability for HP had traditionally supplied ed mobile phone users because only mobile test. The 8642 generators general-purpose instruments for one subscriber could use each tele- were notable because they used sur- transceiver measurements. But phone channel at a time. Moreover, face-acoustic-wave technology to starting in about 1979, the 8901A base stations were spaced quite far improve signal-to-noise performance modulation analyzer directly targeted apart, significantly restricting fre- of the programmable oscillators, the mobile transmitter test market. quency reuse. even over cavity-tuned models. The analyzer was essentially a 1000 MHz, calibrated receiver that Frequency counters, power meters, A brand new concept for RF volt- accurately and precisely measured and signal generators were the meters was introduced in 1966 when the AM, FM, and phase modulation instruments of choice for designing, the 8405A vector voltmeter was of mobile transmitters. testing, and maintaining mobile launched. The use of impulse sam- transceivers. The 803A impedance pling technology (described later) By combining the 8901A with bridge (ca. 1950) featured a novel made this voltmeter unique. By the 8662A microwave synthesizer application of the slotted- line tech- applying the technology to two inde- (ca. 1962) and 8903A audio modula- nique that allowed a 500 MHz mea- pendent but synchronous channels, tion analyzer (ca. 1980), along with surement range in a very compact both channels of RF voltage could be some signal switching, specialized device. This bridge and the 805A measured to 1000 MHz, and the phase test systems such as the 8957S slotted line (ca. 1951) were used for difference between the two could be cellular radio test system (ca. 1985) impedance measurements on RF and measured, as well. This remarkable were created. antenna sections. capability offered the RF mobile design engineer new insights into RF printed-circuitry performance.

15 Modern wireless communications

By the 1980s, the frequency-spectrum In recent years, the company has digital radio. Today’s ESA series overload in mobile telephony was focused attention on the evolving spectrum analyzers carry on the becoming obvious. And one dramatic needs of mobile manufacturers for trend with evolving personalities solution was waiting in the wings—the complex test equipment customized for CDMA and GSM. concept of cellular frequency-reuse, to exact modulation formats and sig- which envisioned a dense population nal performance. Before that, equip- The ESG-series RF signal generators of base stations at regular (cellular) ment was designed primarily for (ca. 1995) have provided flexible digi- intervals, and a complex control sys- general-purpose use. But system tal modulation for an exceptional tem that would “hand off” a travelling designers now want test equipment range of RF communication applica- transceiver as it moved from one base that anticipates sophisticated new tions to 4 GHz. These include GSM, station cell to another. The idea was technologies. As we can see from the CDMA, TDMA, DECT, EDGE, and revolutionary, but new microproces- three dozen pages of wireless test broadband I/Q modulation. In addi- sor technologies made it possible and equipment in the 2000 Test and tion, an internal arbitrary waveform economically viable. Measurement Catalog, Agilent has generator can play back virtually any learned this lesson well. mathematically generated waveform— We can only pity those early radio an amazing signal simulator in a tra- designers who had to create RF front Mobile systems now evolve so quick- ditional RF signal generator package. ends for mobile radios that encoun- ly that the key to success is agility. tered some of the worst signal degra- Test equipment suppliers must be With the 8960 Series 10 wireless com- dation imaginable. The radio had to quick to respond to customer needs. munications test set introduced in capture and retain the base-station sig- So, for example, because spectrum 1999, mobile phone manufacturers nal, while a car, traveling at high analyzers are often the most critical could achieve breakthrough speed that speed, exhibited a considerable piece of test equipment on the could improve test throughput by up Doppler effect in frequency shift. At design bench, the 8590-series spec- to 300% in a system designed to test the same time, multipath effects trum analyzers (ca. 1988) were multiple communications formats. caused by mountains, buildings, or given plug-in firmware “personali- atmospheric conditions might be caus- ties,” each of which customized the Today as third-generation (3G) and ing the signal strength to fade into measuring routines to specific jobs. interim 2.5G digital wireless stan- black holes with 70 or 80 dB attenua- Numerous and inventive test rou- dards emerge, Agilent is launching tion. Enter the 11752A multipath fad- tines have been offered for testing manufacturing, field-service, and ing generator (ca. 1985), which simu- cable and broadcast TV, noise figure network operations test systems to lated up to six multipaths with indi- or EMC, and a multitude of wireless help ensure the performance and vidually programmable amplitude formats, including GSM, CT2-CAI, quality of the next generation of effects, all to stress-test the circuitry of NADC-TDMA, ODC, DCS1800, wireless network equipment, digital the mobile radio’s signal processing. DECT, CDMA, PHS, and microwave appliances, and services.

In 1992, HP launched a family of compact, portable cellular test sets, many of which are still in use today. The 8920A RF communications test set combined measurements of 22 instruments for transceiver testing of land- mobile and cellular applications. Variations were developed to meet new system formats. The 8920DT focused on digital systems such as PDC. The 8921A cell site test system covered cellular base station testing. Yet another system, the 8924C, targeted CDMA. Test sets were customized for GSM/DCS/PCM applications, for DECT (Digital European Cordless Telecommunications), and even for pagers. Today, base station testing is accomplished with the 8935 series base station test sets for CDMA and TDMA technologies. The 8935 series base station test sets were designed to operate under varying environmental conditions.

16 Agilent Technologies and communications LMDS in the last mile

In the late 1990s, the battle heated up to deliver interactive, broadband connection to homes and businesses, and the industry began to consider wireless technology alternatives (“fixed wireless”). One of the new service formats developed was the Local Multipoint Distribution System (LMDS). Allotted frequency at 30 GHz, LMDS consisted of a cellular arrangement of hub base stations that connected to homes and businesses using very small (8-inch diameter), line-of-sight antennas spaced about every 2 to 4 miles. This arrangement bypassed all the headaches of laying underground cable and required easily installed modems at the customer premises. HP developed a two-way LMDS technology for broadband, interactive connections that was sold in 1997 to Lucent Technologies.

17 Military communications

With vast and far-flung operations, A fellowship grant made to Al Bagley, ing in the early 1950s with the 524A the world’s military forces rely a young graduate student at frequency counter (ca. 1952), which heavily on tactical and strategic Stanford University in 1948, led boasted a 0.01 cps to 10 “mc” mea- communications. Most countries the development of HP’s frequency suring range. It was augmented with want to develop the most highly counters. Hewlett and Packard per- the 512A frequency converter to sophisticated, high-performance sonally asked Bagley to study the measure to 100 MHz. communications technology possible measurement needs of the nuclear to assure success in their complex physics industry. From that study In 1954, plug-in downconverters military endeavors. And while the came the requirements for a faster were added and introduced as the military certainly depends on large nuclear-pulse-counting technology 524B electronic counter, which amounts of commercial communica- that could resolve two nuclear became an industry standard for tions capacity, in every decade the events only 0.1 microsecond apart. some years. Plug-ins eventually mea- military has had unique needs that Bagley determined that new, low- sured to 18 GHz, after the introduc- have pushed communications tech- capacitance semiconductor diodes tion of the step-recovery-junction nology to the limit. just coming on the market might diode. With this diode, HP’s design allow faster digital circuitry. He built engineers could create a broad comb One of the earliest products devel- a prototype as part of the project— of harmonic spectra from a crystal- oped by HP during WWII was the and asked for a job at HP. When he stabilized frequency source in the 100A secondary frequency standard was hired, he was asked to continue 200 MHz region. This down-conver- (ca. 1941). This crystal-controlled the work. sion technology allowed convenient oscillator had countdown circuits to measurements to 18 GHz, a real provide precision outputs to 100 kHz Out of that work came the 520A high accomplishment at that time. and was used in certifying transmit- speed decimal scaler, which was able ter frequencies. In those days, fre- to condition very short nuclear puls- Development of the 5100A frequency quencies were often standardized es occurring at up to 10 MHz, and to synthesizer (ca. 1964) came about in using the “Lissajous” comparison divide down by factors of 10 or 100. response to the U.S. Navy’s critical pattern on a cathode ray tube, which Sadly, the 520A had only minimal need for a fast-switching, direct syn- placed a standard frequency on the commercial success. However, thesized, high resolution signal horizontal deflection, and the Hewlett envisioned a different source for secure communications. unknown signal on the vertical. The measurement process, one that gated The product was a marvel of the 500A frequency meter (100 kHz) of those scaled-down, high-speed pulses time, covering 0 to 50 MHz with a 1941 used an analog meter dial. (using a selectable time base similar resolution of 0.01 Hz and crystal fre- to that of the 100A quency stability of 1 part in 1010. Its time standard) into success launched HP into a long line a slower-speed of direct synthesizers that became accumulator faster, wider in range, and more flex- (counter). Thus the ible. The 5105A frequency synthesiz- common frequency er, offering 500 MHz direct synthesis, counter was born. followed in 1967.

Frequency coun- HP’s first entry into the RF measure- ters were a huge ment sector was introduced in 1943. commercial success The Model A signal generator, a UHF and in great (ultra-high-frequency) signal source demand from the with a 500 to 1350 MHz range, used 1950s onward. “lighthouse” vacuum tubes for the They were used in oscillator and power amplifier. measuring every- Frequency adjustment was made thing from trans- through ganged, tunable cavities. mitter frequencies to the accelerome- To fulfill a wartime government pur- ters on which bal- chase order, HP developed some listic missile guid- sophisticated manufacturing ance systems were processes that served the company based. HP became well for decades. For example, the the industry leader design of the Model A used move- The 524 frequency counter established HP as a leader in electronic counting. in electronic count- able, contacting short-circuit

18 Agilent Technologies and communications “fingers” to provide the cavity resonance function for the oscillator. Those fingers were assembled and worked in with a careful burnishing process. This process smoothed the sliding metal surfaces so that electrical noise would not occur as an operator tuned the frequency across the band. The manufacturing process also ensured a long life for the cavities despite the wear from continuous movement.

A commercial version of the wartime product, the 610A UHF signal generator, was introduced in 1948. The 612A UHF signal generator (ca. 1953) found applications in UHF television, which had been opened up for broad- The 5100A frequency synthesizer answered the military’s need for a fast-switching, direct-synthe- cast communications at that time. sized, high-resolution signal source.

The early HP signal generators provided user features that contributed nal generators, and the first was the microwave frequencies and a diode to the company’s dominance of the 616A signal generator (1.8–4.2 GHz) at low frequencies, thus allowing the signal generator market for decades. of 1947. The 614-series signal gener- attenuation of an array of these These included direct readouts of the ators covered frequency bands to 21 diodes positioned along a microwave frequency, amplitude, and modulation GHz and were replaced in 1962 with transmission line to be programmed functions—a big advance in usability. the 8614/16 signal generators that with a dc current. Also, the instruments incorporated featured power leveling and ampli- mutual inductance coupling and tude modulation using PIN (positive- It was not until 1982 that solid-state waveguide-beyond-cutoff technology, intrinsic-negative) diodes. PIN YIG (yttrium-iron-garnet) sources which allowed precise attenuation of diodes made a significant contribu- were introduced in the 8683/84A the output signal down to extremely tion to microwave amplitude con- signal generators, which covered low levels, on the order of 1 microvolt. trol. They were created by adding an the 2.3 to 12.4 GHz range with intrinsic layer of silicon in the mid- AM/FM/pulse modulation, making Klystron tubes were the power dle of a standard PN junction. A PIN them suitable for many microwave sources of early HP microwave sig- diode acted like a resistor at communication applications.

Tactical aircraft communications and navigation systems have been calibrated and maintained by a long line of signal generators, such as the 450 MHz 608A VHF signal generator (ca. 1950). The 65 MHz 606A HF signal generator (ca. 1959) was well- suited for design and testing of the ultra-long-range, single-sideband HF communications radios of the U.S. Strategic Air Command bombers.

Standard HP signal generators have served a variety of other military applications, such as tropos- pheric scatter communications, in which high power signals were aimed at the horizon, and receivers over the horizon had to detect the tiny amounts of signal that scattered from ionic elements in the high The 606A high frequency signal generator could test ultra-long-range, high-frequency radios. troposphere.

19 The 8640B VHF signal tions of arbitrary formats generator (ca. 1973) repre- such as non-linear chirps, sented a quantum leap in TDMA, and CDMA. With signal generation, replacing such custom signals, oper- the venerable 608-series ating receivers could be generators that were stress-tested using actual installed in thousands link traffic and congested of radio test benches. signal environments tested To achieve superior phase with in-channel and out-of- noise in the new product, channel interference. the designers used a cavity-tuned oscillator to Some military satellite 512 MHz. They phase-locked work, such as the MILSTAR the oscillator for drift stabil- satellite program, required ity, and used a power ultra-complex modulations doubler for 1024 MHz out- and frequency-agile for- put. The digital countdown mats to make them secure circuits went to 500 kHz, from jamming and other and an internal frequency mischief. Sophisticated counter gave user precision. generators such as FASS The 8640B offered very Vector signal analyzers such as the 89441A process highly complex, and other millimeter-wave high-performance AM-FM modulated signals to obtain both phase and amplitude information. signal source modules signals to military radio were introduced there. testing for a decade. design was directly focused on signal Hybrid spectrum analyzer technolo- As high-frequency digital circuits generator performance standards, gy integrated frequency- and time- became available, HP developed a and the AWS far exceeded ordinary domain functions to process highly powerful digital direct-synthesis fast (computer-style) DAC perfor- complex modulation signals for both technology for use in secure commu- mance in signal-to-noise ratios and phase and amplitude information. nications. The 8770A arbitrary wave- harmonic generation. These are typified by the 89410 to form synthsizer (AWS, ca. 1988) 89450A vector signal analyzers created completely arbitrary wave- Next came fixed upconverters that (ca. 1993), which still offer unparal- forms from dc to 50 MHz by use of a could place the agile 50 MHz band leled capability, from baseband to super-fast, digital-to-analog converter into microwave application frequen- 10 MHz and from RF to 2650 MHz. (DAC). This circuit could plot com- cies. Then in 1991, the 8791A fre- Powerful signal processing software puted-amplitude points to create quency-agile signal simulator (FASS) contributes useful displays of digital totally arbitrary waveforms using added frequency-agile upconverters modulation, statistical parameters, 8 nanosecond-width pulses. HP’s that achieved a typical 100 nanosec- and advanced data analysis functions. frequency-agile technology also made ond agility all the way to 18 GHz. In Thus the analyzers can display time it possible to hop from one frequency addition to impressive carrier agility, patterns of digital modulation such to another in the time it took to move FASS used a special waveform gen- as eye-diagrams concurrently with to a different sequence of 8 nanosec- eration language that allowed users phase patterns such as constellation ond pulses. More importantly, the to program wide-bandwidth modula- and vector diagrams. Innovative waterfall and spectogram display formats give insight to communication traffic characteristics.

The 8604B VHF signal generator featured built-in phase locking and a 550 MHz counter for high- performance AM and FM signal testing.

20 Agilent Technologies and communications Environmental testing

Products built for military communi- This observation led HP to imple- cations have influenced the commer- ment an instrument class of envi- cial market in important ways. For ronmental specifications that all HP example, a high standard of perfor- commercial products had to meet. mance of HP and Agilent instruments Class B instruments had to operate has dramatically affected the owner- from -40 to +65 degrees Celsius, and ship experience of the company’s perform to specifications from 0 to customers over the years. This +55 degrees C. During the design performance standard was initially qualification of an instrument, the the result of HP’s so-called “Class B” entire parts list was analyzed, part environmental qualification. by part, to determine how much de- rating would be used. For example, In the early years, when HP occa- resistors were to run at only 25% of sionally contracted to design milita- their maximum published ratings. rized test equipment for the rugged Since heat is generally the killer of field conditions of the armed services, reliability, IR scans were made on the operating requirements included chassis and printed circuit boards a wide range of thermal and to identify spots of unwanted heat. mechanical stress. It was found, not It is generally accepted that these surprisingly, that when those instru- rigid programs of operating qualifi- ments were later commercialized, cations were fundamental in build- their failure rate and field reliability ing the high esteem held for HP and were often superior to many other Agilent products. ordinary designs.

21 Broadcast communications

Certainly HP's early audio oscillators and distortion analyzers (such as the 330B distortion analyzer, ca. 1941) found use in the broadcast industry, which in the 1940s meant simply AM radio broadcast. As frequency modulation technology was introduced to the broadcast community, the FCC required instrumentation at the broadcast station to continuously monitor the transmitter frequency and the modulation characteristics. In 1947, HP introduced the 335B broadcast service monitor to meet these FCC broadcast rules. Other broadcast monitors followed, with the 335E TV waveform monitor in 1945 and the improved 337B FM monitor in 1950.

The early development of television took place in the late 1930s and was The MediaStream broadcast server dramatically improved storage and playback capability for demonstrated at the New York broadcast television stations. World's Fair in 1941, but implementation was put aside during WWII. In the 1990s, video technology the same sheet. In this way, video When postwar television rolled out, underwent a dramatic conversion news and other cassettes could be HP equipment was in demand for sig- from analog signal format to digital. inventoried for easy access when nal simulation and analysis. The The timing was right for many rea- studios needed to retrieve specific 612A UHF signal generator (ca. 1953) sons: picture quality was higher, video clips. The product served an became the signal source of choice precision post-production editing important inventory function for a because its modulation capability was available, dramatic improve- few years until replaced by on-line was specifically designed for the ments had been made in digital stor- photo shops. UHF TV modulation formats. This age techniques, and reliability of the product was a direct descendent of technology had improved over earli- Other products for the digital video the 1943 Model A signal generator. er digital video tape. HP was confi- market included a line of digital dent of the opportunities and creat- video recorders and video servers. When HP entered the oscilloscope ed a division just to supply the In 1993, HP introduced the market in 1958, various specialty broadcast video market. MediaStream broadcast server. This markets looked promising for the product’s technology offered a dra- new scope technology. In 1965, the One of the first products was a novel matic improvement in storage and 191A TV waveform oscilloscope was frame-grabber-type video data playback capability for broadcast introduced for broadcast studios to processor called the VidJet-Pro stations and post-production stu- test the quality of the video signal. video print manager (ca. 1994). It dios, first for 1 or 2 video channels Some of HP’s oscilloscope innova- was designed for broadcast and and later for up to 6 channels. It tions, including the internal gratic- post-production studios, which had offered 50 hours of video storage ule for a more precise display and a walls full of video tape files. By pro- for advertising or spot media con- flood gun for illuminating the cessing video data from a streaming tent. Through integration with pro- screen, were included in the 191A. video signal, the VidJet could cap- gramming computers, it made digi- This scope also featured higher ture a single video frame and create tal video instantly available, and bandwidth, so it could read and dis- the proper data map, which in turn the new medium began to replace play the VITS (vertical interval test could print the picture on a standard video tape and cart machines for signal), which was a new test signal color page printer. playback functions. transmitted during the TV vertical interval period for concurrent moni- The VidJet provided other functions, Video servers were more than just toring of signal distortions. These such as detecting each scene change modified computer data servers, innovations were important for the and printing story boards with 30 because the video data had to be emerging color technology. slide-sized thumbnail pictures on constantly “streamed” to its applica-

22 Agilent Technologies and communications tions, and not subjected to the data bursts typical of computer servers. HP made real contributions to the industry with the development of RAID (redundant array of indepen- dent disks) technology, which in the case of a disk-element failure allowed reconstruction of the lost video from redundant data on other surviving disks. Broadcast stations moved quickly to exploit the new disk technology. HP supplied similar digital video storage with a line of MediaStream disk recorders. These could scale up to 5 channels with storage capacity up to 18 hours.

In the test world, as analog video gave way to digital video technology, the 11759D dynamic ghost simulator (ca. 1993) stressed TV receivers with real-life signal impairments such as airplane flutter, tower sway, and mountain or building multi-paths. The 8594Q QAM analyzer (ca. 1995) targeted performance testing of digi- The 8594Q QAM analyzer targeted performance testing of digital video signals. tal video signals, including the 16, 64, and 256 QAM formats used for satellite distribution. Group and called MPEG, became the important broadcast and post-pro- main compression technology for duction processes. Today Agilent’s Data compression played an impor- recording and playback of digital MPEGscope family of test products tant role in the new digital video video. The MPEG standard allowed (ca. 1997) are used in the industry broadcast. One standard, developed economical data storage yet permit- for MPEG-2 as well as DVB (digital by the Motion Picture Experts ted editing functions and other video broadcast) and ATSC (Advanced Television Standards Committee) system development and qualification. The MPEGscopes are used to verify and debug digital TV network systems, including encoders, multiplexers/demultiplex- ers, set-top boxes, and video servers. In 1999, the MPEGScope was award- ed an Emmy for technical contributions to the television industry.

In 1999 the MPEGscope won an Emmy award for technical contribution to the television industry.

23 Cable television

HP was an early contributor to the cable industry, even in cable’s first incarnation as community antenna television (CATV) in the late 1940s. Often tiny local companies were built on a shoestring to bring broadcast TV “over the mountain” where direct line-of-sight signals didn’t reach. Some general-purpose HP gear was used in designing the broadband amplifiers and circuit components such as signal splitters and combiners. Certain transmission testers that were used for telephony cable maintenance could be applied to cable TV installation and service, as well.

Powerful yet versatile signal testing The 8591C cable TV analyzer was given a flexible hardware and software architecture that could for the cable industry came about in be upgraded to keep pace with changing regulations. 1991 when the innovative 8591C cable TV analyzer was introduced. acquired CaLan, a manufacturer of turn up two-way systems, the compa- This full-featured spectrum analyzer cable test equipment, which added a ny introduced in 1998 a return path operated a measurement personality new array products including a monitoring and analysis system. For (loaded from a plug-in card) that sweep/ingress analyzer and signal telephony and converged service displayed test parameters for video level meters. testing, Agilent supplies protocol and carrier characterization in the analyzers with voice over IP test units of the application. In the early In recent years, the cable industry capability and a voice quality tester. 1990s HP has faced intense competition from other service providers, including Fiber testing can be performed with direct satellite system (DSS) televi- a mini OTDR, WDM channel analyz- sion and telecommunications. In er, and optical spectrum analyzer. response, cable operators began Digital broadcast test equipment evolving their businesses to (described above) is also used. An supply more than just pack- advanced, automated test suite for aged entertainment. They DOCSIS verification was introduced began to upgrade coaxial- in 1999 to assist in standard certifi- based facilities with cation of new and important tech- fiber-optic technology nologies critical to the deployment and introduce digital of interactive cable services. communication services—including high speed Internet access, telephony, data, and interactive television.

HP—today as Agilent—has addressed the growing com- plexity of cable systems with a wide range of instruments in addition to the traditional cable TV test products. To help cable operators Portable cable TV test products include the 3010 series sweep/ingress analyzer.

24 Agilent Technologies and communications Lightwave communications

The confluence of solid-state laser light sources invented in the 1960s and the low-loss glass fibers developed by Corning Glass Co. around 1970 fostered a communications revolution unmatched in human his- tory. The amounts of digitized voice and data now transmitted by light across continents and under the oceans are so massive that even the greatest visionaries cannot predict where the growth will end. And the production and installation of fiber- optic technologies continue to accel- erate. All these advancements have required the services of new kinds of test and measurement equipment, and fortunately HP was there. For field testing, today’s E6000A mini-OTDR combines powerful measurement tools in a rugged, portable package. The parade of innovative measurement solutions started simply Soon came more sophisticated opti- a test-bench layout for parametric enough. As the first fiber-optic links cal power meters, directly suited for testing of fiber technology. were being developed, the fibers high-performance characterization had generally high loss and were of sources and fibers. The 8151A Several innovations in optical-path best suited for short distances. optical pulse power meter (ca. 1985) manipulation produced continuous Fiber inventors were willing to try offered several interfaces to fibers attenuation control and interfacing to anything that could improve their and sources and featured a well- various fiber standards of the time. By measurements. One engineer thought-out design with two power 1987, HP had introduced a new family derived a simple fiber-power-sens- heads covering the 550 to 950 nm of stimulus-and-response equipment. ing thermistor mount for HP’s regu- and 950 to 1750 nm ranges pre- The 8154B LED source, 8152A optical lar line of microwave power meters. ferred for optical fiber applications. average power meter, an optical atten- The resulting 84801A fiber optic uator, and an optical switch added power sensor (ca. 1981) coupled the At about the same time, HP intro- greater versatility to the tools light from the 0.004 inch fiber pig- duced the 8150A optical signal source, required by optical design engineers. tail into a fly-speck-sized black ther- which provided a calibrated optical mistor bead (about 0.010 inch diam- power source for the short-wavelength As more fiber was manufactured eter), heated the bead, and metered window of 850 nm. Combined with and installed, the 8145A optical it much like microwave power. the 81519A optical receiver and the time-domain reflectometer (ca. optical power meter, these completed 1988) helped engineers characterize transmission characteristics of long lines of fiber. Since only limited peak-pulse power was achievable at that time, the OTDR exploited a very clever, correlation-based, long-pulse technique to extract reflected signals from noise and to look farther down the length of fiber.

The 8702A lightwave component analyzer (ca. 1989) was basically an optical modulation analyzer for bandwidths up to 6 GHz at 1300 nm, and 3 GHz at 1500 nm. It showed in great detail how lightwave transduc- ers (sources and receivers) modified the information-carrying signal. It also boasted a new technique called The 8541A OTDR helped engineers characterize lon glines of fiber. 25 OFDR (optical frequen- up to 120 channel cy-domain reflectome- capacity in the same try). By processing the fiber. Huge capacity for frequency-response digital communications data on a computer, the was in sight—none too designer could deter- soon, since the Internet mine time- or distance- phenomenon was just related imperfections. getting underway.

The 71400C lightwave As the world’s trans- signal analyzer (ca. The 86140 series optical spectrum analyzers have the high sensitivity, wide mission capacity dou- 1988) was the first dynamic range, and exceptional sweep time need to test the current generation of bled, re-doubled, and piece of test equipment WDM components and systems. then went up by factors that could characterize of 100, the Internet and the modulation of optical signals The 8153A lightwave multimeter (ca. the digital communications revolution up to 22 GHz. Measurements of 1991) used plug-in modules to pre- gobbled up capacity. No one knows RIN and optical distortion were cisely measure fundamental quanti- when or if the demand for high band- provided in a calibrated system. ties such as optical power and loss. width will end, but most people recog- This innovation was followed in Available plug-ins included optical nize that without test and measure- 1991 by the 20-GHz 8703A lightwave power meters, fixed-wavelength laser ment, this communications revolution component analyzer, which was the sources, and an optical return loss wouldn’t have been possible. first commercial product incorpo- module. The optical power meters rating a high-speed, Lithium-Niobate became industry standards in the 90s. Today Agilent’s optical test equip- Mach-Zehnder modulator, used ment blankets the industry. For to create the 20 GHz modulated In 1993 came other families of opti- optical component testing there are optical signal. cal instruments. The 71450A optical sources, analysis equipment, and spectrum analyzer and the 8168A automatic test systems for high vol- tunable source ume manufacturing. For field instal- (one of the first lation and maintenance there are commercial tun- optical TDRs (OTDRs), optical multi- able lasers on meters, and wavelength meters. the market) Agilent systems test chromatic dis- offered design- persion, polarization, and the unique ers powerful Erbium-doped fiber amplifiers. new ways to Fiber modulation testers can analyze characterize the digital intelligence transmitted their compo- down the lines. A family of grating- nents and based spectrum analyzers attacks sources. the wave-division multiplex technology that enables the remarkable The mid-1990s 120+ channels per fiber. saw some of the most dramatic Agilent’s OmniBER family of commu- and rapid instal- nications performance analyzers are lation ever of a the market-leading SONET/SDH new technology. testers, testing telecommunications Development of transport networks at optical rates the ingenious to 2.5 Gb/s. The 71612A 12 Gb/s pat- Erbium-doped tern generator and error detector has fiber amplifier become the industry standard tester made possible in labs and production lines for test the distributed, of optoelectronic components and broadband systems in the new, high-speed opti- amplification cal Internet operating at 10 Gb/s. of signals. Wavelength multiplexing offered

Portable SONET/SDH test sets measure optical rates to 2.5 Gb/s.

26 Agilent Technologies and communications RF and microwave component design

There is a broad category of test and measurement instrumentation that serves the R&D engineers designing RF and microwave components, all crucial for high performance communications systems. These components include amplifiers, mixers, filters, combiners, antennas, couplers, oscillators, attenuators, and terminations. With many real breakthroughs, HP and Agilent have been primary con- tributors of R&D bench instruments for component design and test.

Vector network analyzers are important tools. As described earlier, the 8410A network analyzer of 1968 ushered in a revolution in component design and test. Multi-band sweeps of Smith Chart characterizations of components and systems arrived at just the right time for exploiting hybrid microcircuit technology for communications systems.

HP continued to dominate the vector network analyzer category for In the late 1960s, the 8410A network analyzer ushered in a new era in component design and test. decades, with lower-frequency range as well as higher-capability prod- The first implementation of scalar Other families of sweep oscillators ucts. The 8753A vector analyzer (ca. analyzers was the reflectometer tech- followed, with the 8690-series and 1987) covered 3 GHz. Sometimes nique that HP pioneered in 1954. eventually the 8620A-series (ca. called the 8510’s little brother, it This technique used back-to-back 1970), which featured solid-state YIG was the first low-cost VNA operating waveguide directional couplers, a oscillator sources for the first time. below 3 GHz. This positioned it per- motor-swept klystron 670A signal HP’s microwave-component research fectly for cellular design and test source, and a 416A ratio meter to labs contributed exceptional results engineers working in the 800 to 900 test waveguide components at all fre- coupling microwave transistors with MHz frequency range, and later 2400 quencies across their band. Systems Yttrium-iron-garnet technology to MHz range. The 8753 was also the were developed for waveguide bands yield exceptionally stable and high- first RF analyzer to have complete from 2.6 to 40 GHz, and for most power sources. error-correction. coaxial bands. Later came the 8350 and 8340-series Along with the flashy vector network Next came the 890-series sweep oscilla- signal sources. While early sweeping analyzers, another important (and tors, which exploited backward-wave- sources were free-running, sophisti- more numerous) type of component oscillators (BWOs) for signal genera- cated vector network analyzers design tool were scalar network ana- tion, making the sweep electronic. This required phase-locked stability for lyzers. Scalar parameters were con- led to oscilloscope displays with cali- proper error correction. The 8340- sidered entirely adequate for pro- brations grease-pencilled onto the CRT series sweeping synthesizers were duction line test assurance, and screen—not a very aesthetic solution. far more than just sweepers. these analyzers measured SWR The 1416A SWR display (ca. 1966) (standing-wave-ratio) and reflection solved that with a scope plug-in that coefficient, as well as transmission provided calibrated reflection and parameters. transmission data.

27 HP offered a continuing family of RF/microwave scalar analyzers, starting with the 8755 frequency response measuring system of 1972. This was a plug-in for the 180 oscilloscope family, which was specifically designed as a system for scalar parameter testing. The complete system included dual directional couplers for forward and reverse signal separation, RF/microwave multi- band directional bridges, and a new family of wide-dynamic range Schottky diode detectors. It used 30 kHz microwave modulation to extend stability and range.

The 8756A and 8757A scalar network analyzers followed in turn, each with more measuring capabili- The 8757A scalar network analyzer measured scalar parameters of components to 60 GHz. ty and higher frequency ranges, with the 1985 capability at 60 GHz. 1985, the 11740A phase noise mea- ance bridges (components that sepa- HP’s 8970A noise figure meter (ca. suring set combined the 3047A rated forward and reverse signals) 1983) pleased circuit designers spectrum analyzer and the 11729B and probing accessories. For design because they could measure and dis- for a complete solution. The later engineers, the insight gained about play the gain and noise figure para- E5500A-series phase noise mea- amplifiers and a wealth of circuit meters of amplifiers, mixers, and surement solutions covered oscilla- components speeded RF work converters at the same time. Since tors to 26.5 GHz. considerably. circuit designers will gladly trade off a little gain to improve the noise fig- A complete test solution for voltage- Component measurement technolo- ure of an input amplifier, this capa- controlled-oscillators (VCOs) gy grew to encompass many other bility proved highly popular for crit- became available in 1996 with the highly important functional parame- ical applications such as satellite 4352S VCO/PLL signal test system. ters. For example, EMC (electromag- receiver front end design. An earlier This unit characterized 12 different netic compatibility) became a legal 340A noise figure meter (ca. 1958) parameters of the VCOs with clever requirement just about the time digi- measured only noise figure and not techniques to speed the tests, and tal integrated circuits came into gain, so it had only limited useful- they can be installed as production their own. Signal leakage, which ness for component work. test equipment in high volume some referred to as electronic smog, assembly applications. could interfere with adjacent equip- Design engineers of RF and ment or test instruments in two microwave oscillators destined for The first simple impedance meters ways. If a piece of test equipment local oscillator applications in most arrived with the acquisition of the was operating in an environment communications systems have par- Boonton Radio Company in 1960. with a high power transmitter, and ticularly difficult tasks, because The 250A (Boonton) RX meter mea- the equipment’s susceptibility was while their VCO (voltage-controlled- sured reactance to 250 MHz and the high, it could be jammed by the high- oscillator) usually must be agile to unique 260A (Boonton) Q-meter (50 level signal. If its own EMC output achieve channel tuning, it must at MHz) were industry standards on was not designed to be low, its digi- the same time have the lowest phase their own merits. tal circuits and RF oscillators could noise characteristic to minimize out- leak enough level to disturb other of-channel interference. At about the same time (1962), HP’s measurements in the area. 4800A impedance meter (500 kHz) HP’s first product to characterize and 4815A impedance meter (500 RFI (radio frequency interference) microwave phase noise was the MHz) were introduced. The 4815A measuring receivers of the 1970s 11729A carrier noise test set (circa. used the brand new HP sampling were generally mechanically tuned 1983). By downconverting the sig- technology, which downconverted and cumbersome to use. By appro- nal under test using an exceptional- the two channels and measured and priately modifying some early spec- ly “spectrally clean” signal, the displayed impedance and phase and trum analyzers, HP was able to inno- close-in noise spectra could be mea- gain characteristics. Each meter was vate the measurement technology sured and displayed for analysis. In supplied with a variety of imped- with the addition of common anten-

28 Agilent Technologies and communications nas and probes. The 85650A quasi- In the 1970’s, engineering responsi- One final type of instrumentation peak adapter (ca. 1982) was an early bility for RF impedance measuring was the combination spectrum/net- example of an instrument which, instruments transferred to HP’s work analyzer. Consider that spec- when added to spectrum analyzers, division in Hachiogi, Japan. Soon trum analyzers are single-channel gave broad electronic sweep capabil- powerful, multi-function meters sweeping superheterodyne receivers ity and thereby offered the designer rolled out, featuring many highly and vector network analyzers are a wide bandwidth to search for leak- innovative probing stations and two-channel versions. By cleverly age signals. It also provided precise, holding fixtures. This was not sur- configuring a single-channel circuit calibrated data. prising, given the large amount of so that it could also switch its mea- industrial engineering that involved surement between two network With the advent of the 8540A auto- printed and integrated circuit tech- inputs, and by exploiting micro- matic network analyzer in 1968, nologies being done at this time for processor signal processing, HP gave HP had a measuring tool which consumer electronics. birth to the combination 4395A net- could measure the complex ampli- work/spectrum/impedance analyzer tude and phase characteristics of RF Typical instrumentation now offered (ca. 1997). It is especially useful for and microwave antennas. In fact, such capabilities as LCR characteri- testing communications components the technology led to the develop- zation (with the 4263B LCR meter), such as amplifiers and mixers in ment of near-field antenna measur- crystal resonator measurements which both network and signal char- ing ranges. By manipulating the (with the E4915A crystal impedance acterization is required. near-field data of an antenna pat- meter), and dielectric and magnetic tern, computer models could predict test (with the 4291B impedance the far-field performance without meter/material analyzer). Solutions depending on a large outside mea- included software routines to pro- suring range. For military communi- vide design engineers with the latest cations, the ability to use a small, measurement routines, so they inside closed range offers obvious would not have to spend time advantages. researching the field for new measurement techniques. For Agilent Other developments focused on today, selling the measurement tech- the job of totally characterizing niques has become as critical as sell- antennas. Today the product line ing the hardware. includes antenna measurement systems as well as a wide variety of accessories such as computer- controlled pedestals.

29 General communications applications

Some instrument types are so widely used that they could logically fit in any communication test sector. Two obvious examples are the oscilloscope and the spectrum analyzer. When HP began manufacturing scopes in 1958, the company became known for several innovations: quality, low frequency scopes (below 1000 MHz) suitable for many production applications; sampling scopes; and TDRs. HP’s designs also included many convenience features, including beam finders and internal graticules on the CRTs that eliminated parallax errors in readout.

On the benches of communication The 8590 series portable spectrum analyzers could be customized for cable TV, mobile radio, noise engineers, spectrum analyzers are as figure, EMC, and other applications using software measurement personalities. ubiquitous as oscilloscopes. They analyze the frequency domain of sig- HP and Agilent have dominated sensor family was a clever exploita- nals with indispensable diagnostic microwave power measurements tion of a special silicon chip fabrica- power. From the first 8551/851 ana- since the first 430A power meter and tion process that placed a broadband lyzer of 1964, HP never stopped inno- associated 475A bolometer were microwave termination on one side vating. Many spectrum analyzers introduced in 1950. of a thin silicon web, and a sensitive became the starting point for other metallic thermopile on the opposing measuring instruments such as elec- Microwave sensors absorb power side. The meter measured the tromagnetic compatibility analyzers, from a transmission line and heat absorbed heat down to 3 mW and up antenna testing systems, and others. up. By detecting the heat-caused to 20 mW. Since the sensor was a change in resistance of metallic or true power sensing device, it was Modern spectrum analyzers, such as thermistor elements, the first power “square-law” over its entire range. the ESA series, feature digital filter- meters could measure and display ing and all the advantages of the power. The technology was useful, The 436A digital power meter (ca. digital age. Still others have fre- but frustrating for engineers who 1975) provided important program- quency ranges to 110 GHz, and mea- had to detect very low power, since mability for the popular HP Interface sure phase noise and even noise fig- they found that just holding a sensor Bus and also featured a new 8484A ure. Used with tracking generators, in their hands was enough to make power sensor, which used the some spectrum analyzers can incor- the meter drift off scale. square-law detection characteristic porate measurement of scalar net- of a temperature-isolated diode to work parameters. A major contribution was made in measure down to an amazing 100 1961, when the 431A power meter pW. The 437A power meter and the The 8590-family portable spectrum was introduced to take advantage of a 438A dual power meter applied analyzer (ca. 1988) became a fruitful dual-thermistor design. This design microprocessors to provide more progenitor. By downloading a mea- reduced drift 100-fold and also could convenience and functional power to surement “personality” from a card, measure down to 1 microwatt. A measurements. users could configure the hardware whole line of 478/86A sensors cov- and firmware of this highly compact ered a frequency range from 100 kHz In 1997 a new family of power signal analyzer to perform special to 40 GHz and later to 110 GHz. Older meters and sensors was introduced. applications. Cable TV, mobile radio engineers still fondly remember the The EPM-series power meters took testing of many types, noise figure introduction of this useful concept. advantage of new ultra-wide- tests, EMC, and a dozen more appli- dynamic range sensors, the E-series cation personalities featured custom The next big step in microwave power sensors, to measure from -70 CRT display calibrations, and the power measurement came in 1974, to +20 dBm in a single sensor. Such analyzer had an internal card cage to with the introduction of the 435A range permitted measurements accept hardware circuits for unique power meter and its associated right at the receive antenna of signal handling. 8481A power sensor family. This microwave radio systems.

30 Agilent Technologies and communications General technology contributions

There are a few measurement con- ble oscillators running at 200 MHz. tributions that do not involve instru- Discovered by an extraordinary ments, yet cross all lines of commu- engineer, the device was called the nications and are worthy of recogni- “Boff diode” for a number of years. tion. This section will list a few. The name was later changed to the more generic “step-recovery-diode.” The step-recover-diode is one of these contributions. In the early HP exploited this new capability in a 1960s, engineer Frank Boff was variety of ways. HP counters used the working on harmonic-comb genera- harmonic-comb signals to downcon- tors to extend the frequency range vert test signals for counter coverage of counter frequency converters. to 18 GHz. The 8410 network analyzer One circuit showed non-intuitive used a two-channel version to down- results, with high frequency har- convert microwave signals for charac- monics that were more powerful terizing scattering parameters to 18 than theoretically possible from a GHz. Sampling oscilloscopes, after non-linear resistive device such as a prototypes were used to discover the diode. To investigate further, he bor- effect, in turn used the diode to gen- rowed an early lab prototype of the erate large sampling impulses for HP sampling scope to display a time- measurement of fast-transition test domain picture of what was produc- signals. A whole generation of HP sig- ing such rich signals in the frequen- nal generators and sweepers used the The HP 35 pocket calculator changed the way cy-domain. When he finally got the rich harmonics to stabilize microwave we all do math. fuzzy picture focused, he didn't see signals using the technique of indirect the expected chopped-off top of a frequency synthesis. “open system” created a powerful sine wave produced by a diode, design capability for applications but instead saw a sine wave that HP also became the world leader in ranging from research and design to rose smoothly to almost full ampli- exploiting phase-lock loops for fre- production and support. tude, then suddenly crashed to near quency control and programmable Instruments from many manufactur- zero amplitude. switching of microwave oscillators. ers designed with the HP-IB func- Using step-recovery diodes to pro- tionality could be “daisy-chained” At that point, serendipity entered. vide rich harmonics from stable low- together to furnish stimulus test sig- Frank remembered seeing a paper in frequency oscillators and using syn- nals, and measurement data could the IEEE proceedings that theorized thesis techniques such as “divide-by- be taken from a multitude of volt- that such a waveform might exist if n,” sophisticated phase-lock loops meters, analyzers, and other mea- a device exhibited a non-linear were created to discipline suring instruments. The resulting charge-versus-voltage curve instead microwave oscillators and reduce data could be conditioned, manipu- of the non-linear current-versus- their phase noise. In fact, using the lated, and stored. voltage curve that defined a diode. 312A selective voltmeter and an Frank reviewed the article, looked associated tracking generator, HP The IEEE standard became best again at the strange wave-shape, designed a new phase-loop measur- known as the GPIB, or General and proclaimed that what he had ing technique that produced a signal Purpose Interface Bus. It was accept- taken to be a non-linear resistor, or equal to and tracking with the tuned ed by test engineers for its powerful diode, was actually a non-linear frequency of the 312A. This combi- ability to configure large or small capacitor under certain conditions. nation characterized the closed loop test systems. And as an open stan- performance of feedback loops, vali- dard, it was acceptable to all. What he had developed was a varia- dating the fast switching response tion of the well-known P-N diode and loop stability under wide envi- Fast signal sampling technology of that enhanced the stored carrier ronmental performance. the late 1960s enabled another pow- phenomenon and achieved an erful analysis tool to be invented. abrupt transition from reverse-stor- The HP Interface Bus (ca. 1972) was Recognition that a single electrical age conduction to cutoff. The device a solution pioneered by HP to pro- event, such as a pulse, contains all was able to switch tens of volts or vide a practical system for program- the mathematical information need- hundreds of milliamperes in less ming electronic instruments under ed to define its frequency spectrum than a nanosecond. The result was computer control. By developing the gave birth to the Fast-Fourier analyz- the ability to generate milliwatts of system in conjunction with an er. The 5451A Fourier analyzer harmonic power at 10 GHz from sta- IEEE/industry committee, this (ca. 1972) made it possible to

31 achieve real-time spectrum analysis to 300 Hz. That made possible applications in underwater acoustics, medical instrumentation, and vibra- tion analysis. The technology was used in later products with even more amazing results because of faster and more powerful digital computation. The FFT technique was exploited in HP's 89410-series vector spectrum analyzers, described earlier, and used for highly sophisticated communication modulations.

No listing of the company’s technical The modular architecture of VXI enabled development of “instruments on a card.” contributions could be complete without mention of the design engineer’s able to 8K, at $1 dollar per byte.) from multiple suppliers are now personal companion, the HP 35 pocket Storage disks arrived later, as did available, and software routines can calculator. Introduced in 1972, this terminals with CRTs. The real con- be devised to control the measure- (mostly) electronic engineer’s tool rev- tribution of the 2116A was that ment process, many now using the olutionized calculation, replacing slide unlike business computers of the modern plug-&-play concepts of rules and desktop computers for many day, it didn’t need to be coddled. hardware and software. of the engineer's daily computations. It The 2116A was designed specifically provided unparalleled accuracy for for the hostile environment of the A similar open standard was intro- transcendental functions and offered factory floor. duced for microwave applications, many other engineering parameters— the modular measurement system all in a package that fit into a shirt The HP 9100A calculator (ca. 1968) (MMS). It was built for higher-fre- pocket. With four computing registers, was the first desktop computer for quency signal performance with reverse Polish notation format, a HP. Conceived before the availability much more attention given to elec- remarkable 200-decade computing of integrated circuits, its 32-Kbit tromagnetic compatibility and range, and 15 digits, it was an immedi- ROM consisted of a 16-layer printed RF/microwave signal routing. ate hit even at the $395 selling price. circuit board loaded with thousands of discrete diodes. It featured a CRT The 2116A instrumentation comput- display with 3-display registers and er (ca. 1967) brought measurement Reverse Polish Notation, and it revo- and control right to the engineer’s lutionized the expectations of design test bench. The strategy of the com- engineers. It led directly to the 1972 puter’s design was to provide an family of 9810/20/30A programma- accessible card cage on the bottom ble calculators (which would now be layer of the product, which allowed called desktop computers), which programmable instruments to be had HP-IB automation capability. connected to the computer. Each interface card controlled one instru- In addition to integrating instrument, either a stimulus instrument ments with the HP-IB, in 1987 HP such as a signal generator or dc led a consortium of major instru- power supply, or a measurement ment manufacturers to devise a instrument such as fast a DVM, modular architecture, the VXI. This counter, or spectrum analyzer. architecture relied on the previous popularity of the computer-indus- From today’s perspective, these try-standard VME technology, and it automatic systems seem primitive initially focused on low frequency indeed, having the interface of a and RF. Conceived for portable clacking teletype with punched applications, including military, paper tape. The original 2116A con- custom measuring applications troller had a memory based on fer- were configured into standardized rite core technology; basic memory modular cages. Dozens of available size was 4096 16-bit words (expand- compatible instrument solutions

32 Agilent Technologies and communications Superstars

Over the decades Agilent has intro- neers working on components for duced many groundbreaking prod- communication projects, which ucts. Picking the superstars of com- relied heavily on coaxial and strip- munications test is personal, but line transmission structures. here are some of our favorites. Although microwave spectrum ana- The 5060A cesium beam standard lyzers had served the communica- could arguably be credited with stan- tions industry since the days of dardizing the technology clocks of WWII, they were cumbersome to use the world. HP engineers undertook and had narrow dispersions and only the first “Flying Clock” project in modest dynamic range. In 1964, HP 1964, flying two atomic clocks to introduced its first spectrum analyz- Europe to precisely compare the U.S. The 185A oscilloscope was a giant leap ahead er and revolutionized the concept Naval Observatory time with official in RF and digital measurement. and functionality of the instrument. clocks in Switzerland. Atomic fre- The 8551A/851A spectrum analyzer, quency standards had been devel- ments. Using sampling technology, with its 2000 MHz sweep width and oped in many countries to serve as this scope permitted engineers to its 10 MHz to 12 GHz (or 40 GHz with the basic reference based on the measure exceedingly fast transition external mixers) tuning coverage was atomic resonance principle, unvary- times for repetitive, pulsed wave- a marvel of the time. It featured a ing and fundamental. The 5060A, forms. It featured a sophisticated swept first local oscillator, which was designed for rugged performance and triggering circuitry for viewing actu- a backward-wave-oscillator, to long term reliability, became the first al RF waveforms to 1000 MHz. The achieve a wide sweep width. For high commercial product-of-choice in same sampling scope technology led stability in narrow sweeps, it used a industrial primary-standards labs. It directly to the 1415A time domain new technique for phase-locking to a and a long line of progeny came to reflectometer plug-in. The ability to sweeping VHF source. dominate the time and frequency view the time separation of reflec- standards labs of the world. Since tions from a coaxial transmission For the first time, engineers could today’s communication technology structure enabled engineers to diag- look at a huge baseband range and relies heavily on synchronized trans- nose reflections from individual ele- characterize the performance of commission frequencies, everything from ments. For example, the individual ponent and system signals for ampli- cellular base stations and broadcast attenuation elements of the 355A tude and harmonic performance. For television stations to satellite flying VHF attenuator could be seen and example, an amplifier could be oscillators must incorporate such each tweaked for exact 50-ohm per- shown with the fundamental signals precise and stable standards. formance, whereas if all were and all the signal harmonics. The lumped together in an SWR mea- instrument featured an amplitude The 185A/187A sampling oscillo- surement, no corrective adjustments dynamic range of 60 dB, and thereby scope (ca. 1960) was a giant leap could be made. This translated into became accepted as a “frequency- ahead in RF and digital measure- great design power for circuit engi- domain-oscilloscope.” Spectrum analyzers soon became as ubiquitous on microwave design benches as time- domain scopes were on the benches of low-frequency engineers.

An evolution of spectrum analysis instruments ensued. Smaller size, absolute amplitude calibration, and innovative features such as tracking generators made frequency-response measurements simpler. Solid-state local oscillators made the products more stable and reliable. Plug-in designs allowed selection of different frequency bands and conversion circuits. Eventually spectrum analyzers were integrated into automatic systems using modular construc- tion that mimicked the versatile The 5060A cesium beam standard was used to set the world's clocks. plug-in design of laboratory scopes. 33 In 1978, a new generation of spec- The availability of the VNA popular- trum analyzers took full advantage ized the design concept of scattering of microprocessors. In fact, these parameters, which are characteriza- analyzers used three processors tion data in complex impedance for- each. The HP 8568A and 8566A spec- mat, for two-port and N-port trum analyzers—affectionately microwave components. Provided known around HP as the “dooms- with actual Smith-Chart oscilloscope day” machines—had better frequen- displays or phase-gain plots versus cy-tuning accuracy, narrower resolu- frequency, communications design- tion, lower phase noise, and better ers gained powerful insights into phase-lock stability. But the biggest their circuitry. In the microwave feature was the human interface. semiconductor revolution of the These were among the first instru- 1970s, designers raced to develop ments with a lower panel that looked thin-film-on-sapphire integrated-cir- like a calculator keyboard. A single cuit technology to combine the rotary knob gave selectable analog power of microwave transistors with feel for tuning, but the keyboard a variety of circuit elements, includ- offered digital precision. Powerful ing directional couplers, filters, mix- marker functions allowed marking The 851A spectrum analyzer, with its wide sweep ers, converters, terminations, and and measuring of differences and tuning range, was a marvel of the early 1960s. lumped-circuit components such as between traces. And powerful com- inductors and capacitors. The broad- putation routines stored traces so Following 1968’s two-channel 8405A band network analyzer became that one trace could be subtracted vector voltmeter, the 8410A vector indispensable for that role. from another. Maximum signals network analyzer (VNA) of 1968 rev- could be monitored and stored. Most olutionized the characterization of The 8510A network analyzer of 1985 engineers operating this machine for microwave components from 10 MHz brought full circle the tremendous the first time were dazzled by the to 12 (soon 18) GHz. With its insight that component design engi- performance. The spectrum analyzer microwave sweeping source and the neers first realized with the 8410A. had now truly become the “frequen- associated signal-separation test set, Combining the new power of the cy domain oscilloscope.” And with the network analyzer met its original microprocessor with the earlier ana- the HP-Interface Bus (which became objective: to “stamp out slotted lyzer’s extensive capability for char- the IEEE-388 or GPIB), it formed a lines.” Before this, engineers had to acterizing components and systems, central measurement instrument for use tedious slotted-line measure- the 8510A launched a revolution. even more powerful, automatic spec- ments to compute a Smith-Chart Full of user operating features and trum monitoring systems. plot, frequency by frequency. error-correction routines, this 26.5 GHz component analyzer pushed into The VNA’s intro- new application areas. For example, duction came at a it was able to process frequency- propitious time, domain data and render a time- since the domain characteristic of the signal microwave semi- passing through a complex sub-sys- conductor revolu- tem on a chip. tion was just gain- ing headway in The power of the 8510A resulted in design labs around numerous, unexpected applications. the world. With special probing antennas and Microwave micro- innovative software routines, dielec- circuit technology tric characteristics of microwave shrunk the size of materials could be measured. amplifiers and Micro-miniature probing stations and intregrated circuit- fixturing were developed for wafer ry, and demanded testing. Special detection equipment total knowledge of and routines could measure pulsed the complex components that could not survive impedance of all CW signals. the semiconductor chips and on-sub- Importantly, the powerful measuring strate components capability provided by the 8510T net- The 8510A network analyzer combined the power of microprocessors with such as filters, cou- work analyzer system (ca. 1987) was extensive measurement capability to launch a revolution in component test. plers, and mixers. combined with RF and microwave

34 Agilent Technologies and communications circuit-design modeling • A family of compact, software. This process portable cellular test provided the verification sets, launched in 1992, feedback needed to con- combined measurements firm that circuits and fab- of many instruments for rications worked accord- transceiver testing of ing to the design model. land-mobile and cellular HP’s EEsof Division and applications. Variations other companies such as were developed to meet Compact invented sophis- new system formats such ticated microwave circuit- as North American design models in their Digital Cellular (NADC), Advanced Design System GSM, TDMA, CDMA; for software. Now the entire DECT (Digital European communications signal Cordless path could be simulated, Telecommunications); from the data stage and even for pagers. through microwave cir- Today Agilent’s test sets cuits and antennas back for mobile phone manu- to the data stage. The acceSS7 signaling network monitoring system provides network opera- facturing dominate the tional monitoring on a vast scale. industry. The acceSS7 signaling monitoring system took on • In the early 1990s, HP the world’s networks, literally, when Other candidates for the communi- extended its range of test for ATM it was introduced in 1996. Designed cations superstar category are many: (asynchronous transfer mode) and to provide network operational mon- broadband applications by introduc- itoring on a vast scale, it specifically • The 3710A microwave link analyz- ing the Broadband Series Test targeted the world-standard CCITT er family, introduced in 1967, System. The BSTS has been on the SS7 common channel signaling pro- became the industry standard for leading edge of ATM technology for tocol. The design grew out of the ear- installing microwave radio links in switches, routers, and network ser- lier 37900A/C/D signaling test sets. North America and Europe. vices, and it continues to support a growing number of protocols that Scalable and non-intrusive, the • The 3760/61 pattern and error carry voice, data and video services. acceSS7 measures and displays real- detector of 1973 was the world’s These include ATM, frame relay, time information on SS7 switching first commercial 150 Mb/s error rate LAN, LAN internetworking, MPEG-2, data activity, and provides the plat- tester. It helped engineers develop UNI signaling, NNI signaling, W- form for a host of network monitoring the first generation of digital trans- CDMA, and more. and management and business intelli- mission systems. Through several gence applications. For example, it generations it has led to Agilent’s The legacy of innovation continues provides security and fraud operators OmniBER family of testers, the mar- as Agilent provides the communica- with automatic real-time messaging ket-leading SONET/SDH testers tions industry with innovative test status for detecting and reporting sus- working to 2.5 Gb/s. In 1994, the and measurement products such as picious telephone activity. The 71612A 12 Gb/s pattern generator optical spectrum analyzers, a voice- acceSS7 databases gather key market- and error detector was introduced, controlled oscilloscope, voice over ing information, such as usage vs. and it has become the industry stan- IP testers, the industry’s first gigabit capacity, call duration, and unan- dard tester in labs and production and terabit router testers, 3G wire- swered calls. Such data can be used by lines for test of optoelectronic com- less solutions, and many more prod- service providers to optimize benefits ponents and systems in the new, ucts. On the frontier of new technol- and services. By keeping a constant high-speed optical internet operat- ogy, Agilent has launched a family of watch over revenue-critical opera- ing at 10 Gb/s. optical switches that may lead to the tions, the acceSS7 system can generate realization of the much-anticipated information vital to management deci- • Launched in 1975, the 3745A all-optical communications network. sions on network operations, both selective level measuring set was hardware and software. The global HP’s first microprocessor-controlled measurement reach it provides gives instrument that accelerated the test- system operators advance notice ing and troubleshooting of frequency before network performance deterio- division multiplex (FDM) telephone rates, even by small increments. systems by automatically tuning the receiver to the FDM frequency plan.

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Latin America: Agilent's wide range of communications offerings today includes breakthrough technology Agilent Technologies for optical switching, handheld instruments for field-service testing, and drive test systems Latin American Region Headquarters, U.S.A. for optimizing wireless networks. Australia/New Zealand Agilent’s products today Agilent Technologies Australia Pty Ltd (tel) 1 800 629 485 (Australia) For more than 60 years, Agilent those who can take advantage of (fax) (61 3) 9272 0749 Technologies has contributed to the the change will thrive. Agilent (tel) 0 800 738 378 (New Zealand) success of communications compa- Technologies plays a continuing role (fax) (64 4) 802 6881 nies, and our innovations continue in the success of these companies, to influence the industry in many providing the people, technology, Asia Pacific: areas. Today communications com- components, and tools they need Agilent Technologies, Hong Kong panies face waves of new techno- to design, deliver, and manage the (tel) (852) 3197 7777 logy, new business models, and next generation of communications (fax) (852) 2506 9284 increasing customer demand. Only networks and services. Product specifications and descriptions in this document subject to change without notice. To read about the latest contributions, please visit us on the Web at www.agilent.com. Copyright © 2000 Agilent Technologies

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