A Comparison of Line Difference Predictions for Time-Frequency Multiplexing of Television Signals

A Comparison of Line Difference Predictions for Time-Frequency Multiplexing of Television Signals By R. L. S C H M I D T * (Manuscript received January 27, 1983) Studies are presented of a scheme utilizing time-frequency multiplexing (TFM) to multiplex two television signals on a microwave radio channel. This scheme transmits alternate lines of the television signal at full bandwidth, along with a differential signal for the remaining lines. The differential signal is derived by subtracting the true value of each picture element from a prediction for that value based on surrounding elements located in the transmitted lines. This differential signal is then placed on a carrier, and frequency multiplexed with the baseband signal. In this way, two television lines of information can be transmitted in one line time, allowing a second similarly constructed signal to be transmitted during the vacated line. Thus, the television signals will be time interleaved on a line-to-line basis. This paper describes the comparison of two different prediction algorithms used to construct the line-differential signal. Time and frequency domain analyses were carried out on the computer and then verified with hardware testing.