Method and apparatus for digitally encoding color video signals having guadrature modulated subcarriers

摘要

An analog PAL color television signal which is to be encoded is passed through a comb filter to separate the signal into a chrominance component and a luminance component each having a carrier frequency. Each signal is then separately scanned at a rate which is directly related to the color carrier frequency (4.43 MHz) of the signal. The luminance signal is fed to a scanning and holding circuit which scans it at a rate of twice the color carrier frequency or 8.86 MHz. The chrominance signal is fed to a scanning and holding circuit which scans it at a rate which is one-half the color carrier frequency of 2.21 MHz. This scanning and holding of each component signal converts the signals into a corresponding PAM signal. Each PAM signal is then quantized and encoded in a PCM coder. The resulting signals are applied to a digital combiner which thereby produces a digital color video signal.