Multiplexed video transmission apparatus for satellite communications
First Claim
1. In combination in video wave communications apparatus, cooperating transmitter and receiver means;
- said transmitter means including means for delaying a video wave being processed over a predetermined interval;
means for determining a statistical level of the video wave characterizing said wave over said period, means for determining the maximum variation of said video signal level from said statistical level over said period, means for delaying the video wave for at least said period of time, means connected to the output of said delaying means for subtracting from said output video wave said statistical level determined by said statistical level determining means for creating a variation content signal, variable amplification means comprising a first read only memory connected to said subtracting means for amplifying said variation content signal by a scale factor dependent upon the output of said maximum variation determining means, and means for transmitting said statistical level, said scale factor and said amplified variation content signal;
said receiver means comprising means for receiving said transmitted statistical level, scale factor and amplified variation content signal, variable reducing means comprising a second read only memory for selectively reducing said variation content signal dependent upon said received scale factor, means for combining said reduced variation signal and said received statistical level to thereby reconstitute the video wave.
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Abstract
Improved multiplexed communications apparatus distributes plural video signals via a single satellite transponder with enhanced reproduced quality, i.e., improved signal-to-noise ratio. The up-link transmitter delays each signal for one line period, and computes statistics characterizing the preceding subject line (e.g., minimum signal level and dynamic range) which are transmitted during the horizontal synchronizing pulse period. The transmitted video is then shifted in level and selectively amplified in accordance with the line statistics to more fully occupy the available transponder deviation allotted to the channel.
Following satellite frequency shifting and transponder re-broadcasting, the received, modified video is restored utilizing the sync-period transmitted information (minimum level/offset; range/scale factor). Each multiplexed received video signal thus exhibits a substantially enhanced signal-to-noise ratio vis-a-vis video information transmitted in unmodified form.
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Citations
18 Claims
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1. In combination in video wave communications apparatus, cooperating transmitter and receiver means;
- said transmitter means including means for delaying a video wave being processed over a predetermined interval;
means for determining a statistical level of the video wave characterizing said wave over said period, means for determining the maximum variation of said video signal level from said statistical level over said period, means for delaying the video wave for at least said period of time, means connected to the output of said delaying means for subtracting from said output video wave said statistical level determined by said statistical level determining means for creating a variation content signal, variable amplification means comprising a first read only memory connected to said subtracting means for amplifying said variation content signal by a scale factor dependent upon the output of said maximum variation determining means, and means for transmitting said statistical level, said scale factor and said amplified variation content signal;
said receiver means comprising means for receiving said transmitted statistical level, scale factor and amplified variation content signal, variable reducing means comprising a second read only memory for selectively reducing said variation content signal dependent upon said received scale factor, means for combining said reduced variation signal and said received statistical level to thereby reconstitute the video wave. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- said transmitter means including means for delaying a video wave being processed over a predetermined interval;
- 16. In combination in video wave receiving apparatus for receiving a video wave transmission comprising a scale factor, statistical video level over a predetermined period, and a variation content signal comprising the difference between the video level and said statistical level selectively amplified in accordance with said transmitted scale factor, said video wave receiving apparatus comprising means for receiving said scale factor, statistical video level and variation content signal, means comprising a read only memory having plural memory sections each storing a different transfer characteristic and an addressing input port connected to said received variation content signal for selectively reducing said variation content signal depending upon said received scale factor, means for combining said reduced variation signal and said received statistical level to thereby reconstitute the video wave.
Specification