Real-World Technology Ltd

RWT and the History of TVRO

Back in the mid-1970s we talked of TVRO -- Television Receive-Only. In those days satellite TV reception was the preserve of the international operators, Intelsat and Intersputnik, and the American CATV companies, introduced to satellite by the likes of Showtime and HBO, anxious to deliver their premium programming in real time and high quality to every cable operator across the USA.

Intelsat Standard A Earth stations used 26-metre or larger dishes; the Soviet Orbita terminals had 12-metre rigs to receive the inclined-orbit Molniya satellites. The US CATV head-ends needed at least a 6-metre antenna to give 3dB margin above threshold on the Satcom and Westar C-Band programme feeds, with the current 120K LNAs. All rather more than the average backyard could accommodate.

But in true American pioneer tradition, things were stirring down in the garage. Experimenters, enthusiasts, radio hams, were working on microwave front ends and FM demods, and beginning to realise that the satellite TV signals were not out of reach.

H Paul Shuch had designed microstrip low-noise converters for the radio amateur 2.3, 3.4 and 5.6 GHz bands, and it was a small step to adapt them to cover the 4 GHz satellite downlink band. Bob Taggart had designed a low-cost petallized antenna for S-Band community satellite reception. In 1977 H Taylor Howard, in between his work for NASA's JPL, built up a complete C-Band satellite TV receiver from standard microwave parts, with a 70 MHz FM demodulator.

Meanwhile in England RWT's co-founder Stephen J Birkill had taken time out in 1975 from his duties as a BBC transmitter engineer, to build an experimental system for receiving in England the SITE ( Satellite Instructional Television Experiment) TV transmissions beamed to Indian villages, from the NASA ATS-6 geostationary satellite at 860 MHz. At about the same time Arthur C Clarke, the acknowledged father (or was it grandfather?) of geosynchronous communications, had a standard SITE terminal installed at his home in Sri Lanka, courtesy of the Indian government.

Over the next three years Birkill extended his system to 4 GHz, receiving TV pictures from Intelsat, Raduga, Molniya and the new Russian Gorizont satellites, and 11 GHz, where the Italian experimental satellite Sirio and the European Space Agency's OTS, flying test bed for the Eutelsat series, were downlinking. All this work was done with home-built low-noise block downconverters (LNBs) and an ex-BBC 2.4-metre dish.

In 1978 Bob Cooper, a cable TV technical journalist and amateur radio enthusiast operating out of Oklahoma City, heard of Birkill's small dish work and invited him (and his receiver) over to CCOS-78 in Oklahoma, ostensibly a cable TV operators' conference and trade show but destined to become the world's first home satellite TV gathering. Cooper brought Birkill together with California's Taylor Howard and Rod Wheeler of Whitehorse, Yukon (later to form Norsat), Jim Vines (Paraframe), Bob Behar (Hero), Tom Humphries (SCI, M/A-COM), Royden Freeland (ICM), Oliver Swan and other pioneers who helped begin the US home TVRO revolution of 1979-82. At the 1978 show Birkill demonstrated clean NTSC pictures from a 3-metre dish, and Wheeler, together with engineer Steve Ritchie (Satco), presented the first prototype of a consumer TVRO receiver. CCOS-78 also saw the first private satellite TV uplink, when, with TV facilities provided by Dana Atchley III (ACE -- now D3 TV) and a borrowed "mobile" 10-metre 3-kilowatt 6 GHz uplink operated by the show's participants, the conference proceedings were double-hopped to cable head-ends across North America via US domestic satellites of the Satcom and Westar series.

On the way home from CCOS, Steve Birkill met up in Canada with ex-BBC engineering colleague Maurice J Lovelock, and they agreed to form Real-World Technology, to design tuners, feeds and LNAs and provide technical consultancy services for the coming home-satellite boom.

The next 2 years saw an explosive growth in TVRO interest. Bob Cooper was the driving force, writing numerous articles in the popular electronics press and being interviewed for major magazines including Playboy and Time, as well as appearing on national television to demonstrate the potential of small-dish TVRO for bringing high quality multichannel entertainment into rural homes poorly served by terrestrial TV. "Small dish" still meant 3 metres or more, as the US domestic satellites were limited to about 37dBW peak EIRP and commercial C-Band LNAs had only just begun to achieve noise temperatures as low as 85K. But in rural and suburban America a 10 or 12-foot dish in the backyard was no great problem.

Cooper's 1979 Oklahoma show (SPTS-79) was the first dedicated totally to satellite, to be followed by 3 shows in 1980: at Miami in January, San Jose in July, and Houston in November. Many more innovators were coming forward, with receivers -- Andy Hatfield (Avcom), Paul Shuch, John Ramsey (Sat-Tec), Clyde Washburn (Earth Terminals), Robert Coleman, David Barker, Norman Gillaspie; with antennas -- Jamie Gowen (ADM), Bob Taggart (Chaparral), Bob Luly (inventor of the umbrella antenna now used in L-Band transportable satellite telephones); with LNAs -- Dexcel; as well as suppliers of feeds, mounts and accessories. Professional broadcast and CATV suppliers also were seeing a new market, with Amplica, Avantek, Microwave Associates, SCI, Anixter, Microdyne, Scientific Atlanta and others taking an active interest.

RWT's Steve Birkill sent over a replica of his original circularly-polarized 90-degree scalar horn feed, for tests with US reception of the Russian Molniya and Gorizont satellites -- his studies of the Soviet space program (with Geoff Perry) and monitoring of their inclined-orbit operations meant he could instruct the Americans where in their northern sky to point their dishes (the western quasi-stationary point of the Molniya orbit, over Hudson Bay, Canada, was the one used by the Russians for TV distribution). The scalar horn concept, though not new, inspired others -- most successfully Chaparral, to develop their own scalars for the home market, replacing the rectangular pyramidal horns formerly used and leading naturally to the rotating-probe designs. Complete TVRO system prices fell below the $4000 mark; trade organisation SPACE (since supplanted by SBCA) and the first dealerships were established.

Birkill also began a series of articles for Bob Cooper's journal CATJ, and later for the influential "Coop's Satellite Digest", covering the technology of TVRO, with explanations of such issues as block downconversion (most converters of the day were tunable), feed horn design, LNA design (a practical D-i-Y example used Plessey GaAsFETs), tracking polar mount geometry (introducing the concept of declination offset), Ku-Band techniques and threshold extension demodulators. International satellite reception was also covered, as the USA's fledgeling TVRO industry began to export its technology around the world.

Five years into the American TVRO boom, with close on a million 10-foot dishes in use, the premium cable programmers began to realise that these "home terminals" could be an additional source of revenue beyond their normal CATV business. Channels like HBO began to encrypt their transmissions with GI's VideoCipher, and, although there were still well over 100 TV channels in clear, the growth of TVRO began seriously to slow down. By the time IRDs and subscriber management systems were in place, some of the magic had gone. TVRO had lost its pioneer charm and become another arm of Big Business. And America began to think in terms of a future small-dish DBS.

But in Europe things were just beginning. By 1982 Steve Birkill had quit his BBC career -- at that time he was Transmitter Manager at the Holme Moss / Emley Moor high power TV station complex in Northern England -- to concentrate full time on RWT and the satellite business.

To be continued ...




Copyright © 1996, 97, Real-World Technology Ltd.

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