Transmission of telemetry data by existing television systems

By encoding an existing TV system in which the signal contains predictable patterns or redundancy, each of which implies that less than an available bandwidth is being used, it is possible to transmit telemetry data and video simultaneously. A nearly orthogonal system could be inserted into blank portions of an existing black-and-white or color video presentation. Theoretically at least, the added data stream should not affect the existing picture, nor should the existing picture interfere with the added data stream. A demonstration model is described that was designed to measure the effects of adding piggyback data to an existing video system to evaluate results by comparison with known data signals and for subjective evaluation of the resulting picture. The report covers characteristics of black-and-white and color TV systems; determinations on what additional data could be transmitted without interference; and descriptions of a modulator-demodulator, a carrier generator, and other hardware designed to test the concept.