Channel Matching Techniques for 2-Channel Television

Interest and progress in the area of high definition television (HDTV) has led to a wider aspect ratio image as an integral part of the evolutionary process. Encoder systems decompose the wide aspect ratio source image into a center 4:3 image and two side panels, maintaining compatibility with existing standards (NTSC) for the center picture. Transmission schemes then transmit the center image over a standard 6 Mhz TV channel (channel 1) and the panel information over another channel (channel 2). Decoders which accept the center and panel information recombine the signals to construct the original wider image. An example of this technique is utilized in the two channel ENTSC System [1]. Due to linear distortions, various parameters such as hue, saturation, black level, gain and static time delay must be normalized in both video signals before recombination of the wide aspect ratio picture. A description of techniques which employ insertion of a training signal at the transmitter and a microprocessor at the receiver, used to control these parameters is presented in this paper.