VOICE OVER VIDEO
Voice Over Video was a breakthrough for Voice and Data Transmission on TV Networks
In the early days of TV networks it was not know how to combine the audio with the video. The early terrestrial and satellite networks transmitted the TV sound on the telephone network. This was expensive, very low quality, and often lead to voice to video sync miss-matches. Below are examples how Voice Over Video solved some of these problems
Western Microwave had a cable TV microwave network serving cable companies throughout Montana.The US Government had Titan missile sites in isolated areas of Montana where there was no telephone service. WTCI was ask to find a way to use it’s microwave network to provide telephone service to these sites.WTCI came to the TDC at Coastcom to see if we had a solution. Coastcom combined their specialized low density telephone multiplex with a TV subcarrier to solve the problem. A test package was put together and was successfully tested on the Montana cable TV network.
A lot was learned about video microwave and subcarrier threshold characteristic, inter-modulation problem between the video subcarriers and where was the optimal location on the baseband for the VoV subcarrier.
WTCI NETWORK MAP
INTELSAT World Wide Use of VoV
In the early days of INTELSAT’s worldwide satellite network it made it possible to get breaking news from Europe and Asia. Here again the sound was a telephone quality circuit on the submarine cable with the resulting quality and sync problems. The use of a full satellite transponder was very very expensive. INTELSAT developed half transponder video to cut costs. Conventional TV sound subcarriers were tried to cut out the telephone lines but was not successful due to the bandwidth constraints of half transponder transmission. The Canadian Broadcast Network and TELSAT had the same problem.
INTELSAT came to the TDC team at Coastcom to solve what was considered an impossible problem of audio transmission on half transponder video. What we learned on the WTCI project was applied to INTELSAT’s half transponder TV transmission an it was very successful and at the time became the world standard for half transponder TV sound transmission. The VoV solution was also adopted by the Canadian Broadcast Network transmission on the Anik satellite network.
Mr. Johnson was awarded three US and Canadian patents for his development of VoV.
Intelsat Lab team in WDC
VoV Video Baseband Spectrum Shot
VoV Subcarrer Mux Configuration
Field tests in Montana
Tipical Montana Facility
Intelsat Jamesburg test site
Jamesburg Equipment Room
Walt Running Test on Intelsat Bird
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