Improving the Transient Response of Television Receivers

Larger kinescopes and the advent of compatible color television have given increased importance to the problem of improving the transient response of television receivers. This paper is concerned with receiver design factors that make for improved electrical fidelity, although the interlocking nature of the transmitter and receiver requires some consideration of the transmitter aspects of the problem. In the receiver, the electrical fidelity is primarily determined by the delay distortion produced in the video IF amplifier, and the extent to which this distortion is compensated in the peaking circuits of the video detector and the video amplifier. Optimum results are obtained by working with both the phase-delay characteristic of the over-all receiver and the corresponding amplitude characteristic. In color receivers, prevention of delay distortion has been found to be of primary importance, as might be expected from the fact that the channel is being used to greater capacity. The factors which determine cross talk between the I and Q color-difference signals and coincidence of the luminance and chrominance information are described. Ultimately, obtaining a uniformly high standard of receiver transient response depends upon industry agreement on a standard monitor. Widespread use of a standard monitor should go far toward eliminating the present tendency for receiver designers to vary their designs to meet the peculiarities of particular transmitters.