Abstract: A differentially encoded digital signal waveform is generated as a discrete time representation of a desired analog signal utilizing multi-frequency modulation techniques. The computational capability of present day, industry-standard microcomputers equipped with a floating point array processor or digital signal processor chip is utilized to perform digital frequency encoding and compute both discrete Fourier transforms and inverse discrete Fourier transforms to provide a transmitter and receiver system utilizing suitably programmed microcomputers coupled by a communications channel.

Abstract: A video multiplexing communications system for distributing two distinct video programs via a single satellite channel utilizes time division principles, transmitting alternating lines of video information for the two programs by a single frequency modulated carrier to increase FM carrier-to-noise, thereby also maintaining each video program signal-to-noise ratio above FM detection threshold. The alternating lines are compacted in time and occupy a substantial portion of the synchronizing pulse period of the video lines; one line is partially repeated to reduce spurious system transient responses upon inter-program line switching; and amplitude expansion/reduction may be employed to maintain a large FM carrier deviation.

Abstract: A television communications system enhances the video signal-to-noise ratio by delaying video intelligence over an interval (as by loading the video into a store therefor), while obtaining a measure of its average value and dynamic range. At the transmitter, the video is then read out from memory, has its average value diluted and is amplified before transmission to approach the channel amplitude capacity.At the receiver, the communicated average value and dynamic range signals are utilized to restore the average value to the received wave--and to appropriately reduce its relative amplitude. The concomitant channel amplitude reduction, with offsetting amplitude enhancement at the transmitter, improves the composite channel transmission ratio.