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Satellite Receiver CT200RS CATV Headend Equipment CT200 [1] and, like the latter, can be remotely con- trolled and monitored via a Windows TV reception with analog and user interface. But stand-alone opera- digital sound from outer space tion is possible too, without restrictions. Function As an extension to the CATV Headend Equipment CT200, Rohde & Schwarz now offers a satellite receiver for analog TV programs able to receive both The satellite signal arriving from the conventional two-channel analog and digital ADR programs. Thanks to the antenna on the first IF is converted in a comprehensive remote-control capabilities of the system components, a new tuner module with high image-frequency concept for broadband cable networks can be implemented. rejection to an internal (second) IF and

FIG 1 Satellite Receiver CT200RS used as fore expedient to abandon the use then frequency-demodulated (FIG 2). component of Rohde & Schwarz CATV Headend of expensive modulation lines, inter- This second satellite IF is available for Equipment CT200 or as stand-alone unit Photo 42 440 ference-prone terrestrial relay receivers monitoring and external processing. or complex microwave links for feeding An AGC (automatic gain control) circuit signals, for example, to CATV headend matches the gain in a wide input-level equipment and terrestrial transmitters range (–65 to –20 dBm). The switch- A large number of TV programs are and to utilize satellites that can be able AFC (automatic frequency correc- broadcast in Europe via the satellites received everywhere with a minimum tion) compensates frequency offsets Astra and Eutelsat. Normally, stereo of outlay. For this purpose Rohde & even in case of weak input signals (eg sound programs are also transmitted Schwarz developed the Satellite Re- signals impaired by heavy rain) and with the satellite signal. It seems there- ceiver CT200RS (FIG 1). It extends the thus ensures optimum picture quality.

News from Rohde & Schwarz Number 151 (1996/II) 13 Articles

Baseband Satellite Receiver CT200RS several

2nd IF (479.5 MHz) Synchroni- times. For this reason, one of the zation CT200RS models, Sound Subcarrier Satellite IF (920 to 2050 MHz) Demodulator CT200SS, comprises Satellite PLL Ku band Clamping Noise Video tuner demod. C band circuit trap signal only the sound section of the satellite Base- band receiver and is fed from the baseband Audio Power supply Polarity Noise AF output. Thus several subcarrier demod- signal low-noise block reduction left ulators can be operated from one

Audio baseband signal. The ADR demodula- SERBUS Noise AF signal decoder reduction right tor/decoder option may also be fitted in the subcarrier demodulator. Option ADR Demodulator/Decoder CT200DR With several satellite receivers con- Sound Subcarrier Demodulator CT200SS nected to one antenna, Active Satellite Splitter CT200A8 provides eight out- puts each for horizontal and vertical FIG 2 Block diagram of Satellite Receiver may optionally be equipped with ADR polarization and covers the frequency CT200RS and Sound Subcarrier Demodulator Demodulator/Decoder CT200DR for range 920 to 2050 MHz. A low-noise CT200SS retrieving the digital ADR-modulated amplifier compensates for the distri- subcarriers (ADR = Astra Digital Radio bution loss. Redundant power supplies [2]). The option comprises the QPSK ensure optimum operational reliability. demodulator required for ADR, a CT200A8 may optionally be equipped The subsequent polarity switch makes Viterbi decoder (error protection) and with an (n+1) output giving access to Satellite Receiver CT200RS also suitable the MUSICAM decoder. Ancillary data the two types of polarization. for C-band reception (3/4 GHz) which, transmitted with ADR signals are avail- contrary to the Ku band (11/12 GHz) able for further processing, eg for an Uses commonly used in Europe, employs in- RDS coder. verted deviation. After the deemphasis CATV headends mostly handle several circuit prescribed by CCIR Rec. 405-1 Since it is common for sound pro- signals from a satellite. Active Satellite the baseband signal consisting of a grams to be transmitted in the satellite Splitter CT200A8 distributes the ver- video component (0 to 5 MHz) and signal as subcarrier pairs besides tically and horizontally polarized IF sig- subcarriers (6 to 9 MHz) is available the TV sound signals, it would seem nals from the antenna to seven channel for video and sound signal processing. appropriate to use the baseband of paths (FIG 3). The eighth output is re- quired for the (n+1) standby channel. In the video section of the receiver the A Satellite Receiver CT200RS is con- sound subcarrier is separated and only nected to each of the two times seven the video signal is allowed to pass FIG 3 Satellite Receiver CT200RS in CATV direct outputs of CT200A8, each of through. A clamping circuit removes the headend equipment with (n+1) standby which provides a TV program consist- super-imposed energy-dispersal signal, which ensures that intermodulation products generated in the satellite transponder do not cause visible inter- FMFM ++ DSRDSR CCVS ference on the transmission link. If the Modulator path input level is too low or if no sync signal is received, a noise trap switches off CCVS Modulator the video signal at the program output. path

The monitoring output remains active Broadband DC+920 to 2050 MHz communication for measurements. CCVS network Modulator path Coupling network

The sound section of Satellite Receiver Vertical Active Satellite Splitter CT200A8 CCVS CT200RS consists of two FM subcarrier Modulator path demodulators which receive the analog sound signal accompanying the TV CCVS Modulator signal or one of the audio programs as path a mono or stereo signal. CT200RS (n+1) standby configuration

14 News from Rohde & Schwarz Number 151 (1996/II) Articles

ing of a video and stereo signal or a Satellite Receiver CT200RS and Sound shown in the example. In the case of two-channel sound signal. Each satellite Subcarrier Demodulator CT200SS may ADR subcarriers, QPSK demodulation receiver is followed by a CT200 mod- be used not only in CATV headend as well as Viterbi and MUSICAM de- ulator comprising Vision-Sound Mod- systems but also in converter systems coding are performed in the optional ulator CT200VS, Sound-2 Coder and gap-filler transmitters. Since ADR Demodulator/Decoder CT200DR. Modulator CT200S2 and Upconverter nowadays many broadcasting author- Gregor Kleine CT200UP. If additional IF inputs and ities emit their TV programs together RF outputs or higher output level are with their own sound programs via required, CATV Interface CT200CI satellite, a TV and FM converter system may be added. TV signals, FM sound or gap fillers fed from satellites can programs and possibly a DSR signal easily be set up (FIG 4). Satellite Re- are combined by passive or active ceiver CT200RS receives the signals coupling networks (eg CT200C6, from the desired satellite transponder CT200A4) and the sum signal is for- and, in addition to the video signal with warded to the broadband communica- two-channel sound, it provides a base- tion network. band signal comprising the FM pro-

DC+920 to 2050 MHz CCVS TV exciter

FM stereo transmitter Baseband FIG 4 FM stereo Example of converter transmitter FM system for one TV FM stereo program and three transmitter FM programs

REFERENCES [1] Schönberger, P.; Sturm, P.; Scheide, R.: Comprehensive monitoring and re- grams in the form of analog or digital CATV Headend System CT200 – CATV signal processing intelligent, compact, ver- mote-control capabilities of all active (ADR) subcarriers. This baseband sig- satile. News from Rohde & Schwarz (1995) CT200 components permit for the first nal is looped through Sound Subcarrier No. 148, pp 23–25 time an (n +1) standby configuration to Demodulators CT200SS, each of which [2] Kleine, G.: Astra Digital Radio – Die Technik. be implemented. The supplementary retrieves one of the three FM programs Funkschau 68 (1995) No. 10, pp 44–47 channel (satellite receiver and modula- tor) may replace any of the operating channels. The software used by Con- troller CT200CO holds the configura- Condensed data of Satellite Receiver CT200RS and tion of the headend equipment. The Sound Subcarrier Demodulator CT200SS controller monitors the whole headend Frequency range 920 to 2050 MHz system. If a component fails, the stand- Input sensitivity –65 to –20 dBm/50 Ω by transmitter can be remotely tuned to Image-frequency rejection >45 dB the respective satellite transponder. AFC capture range ±10 MHz CT200RS selects one of the two pola- IF bandwidth 27/32 MHz, selectable rizations with the aid of its LNB (low- Video polarity selectable for C and Ku band noise block) feed voltage and the (n+1) Video deemphasis CCIR Rec. 405-1 option in the IF satellite splitter. The Video S/N ratio >60 dB controller finally tunes the standby mod- Video output voltage 1 Vpp into 75 Ω ulator to the required output frequency Subcarrier frequency range 5.5 to 9.99 MHz and connects it through. The inopera- Stereo channel separation >80 dB tive channel path is remotely switched Unweighted S/N ratio >64 dB off and signalled defective to the con- Audio deemphasis 50 µs/75µs, J.17 trol center. The (n+1) standby configu- Audio output level +9 dBm into 600 Ω ration can be retrofitted any time in Reader service card 151/04 existing systems.

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