The S terminal cable is mainly used to provide a connection cable for the TV to output video signal interface.
At present, many video cards have added video output. As far as the installed video output is concerned, there are mainly S terminal output and ordinary composite video output.
The S terminal is a five-core interface, consisting of two video luminance signals, two video chrominance signals, and one public shielded ground wire. There are five core wires (in fact, there are matching luminance and chroma separators). It is not difficult to see from its structure that it is a device used to separate the output of brightness and chrominance. Why do we do this? This design is mainly to overcome the mutual interference of brightness and chrominance in the composite output of video programs. The brightness signal bandwidth of general broadcast television is 6MHz, while the domestic PAL standard color signal bandwidth is 1.5MHz. The composite video output is to place the chrominance subcarrier signal at a frequency of 4.43MHz into the video luminance signal, perform chroma demodulation during the display output, and filter the chrominance subcarrier from the composite video signal, which may be lost The frequency of 4.43MHz ± 0.75MHz in the luminance signal reduces the horizontal definition. In addition, the chrominance subcarriers that are not completely filtered out may interfere with the luminance channel, and the luminance signal at the edge of 4.43MHz will enter the chrominance demodulation circuit, which interferes with each other and reduces the broadcast quality. Separating the brightness and chrominance output of the S terminal can improve the picture quality, which is why some people call it "high definition output".