Importance

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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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First Claim