A Method for Exactly Decodable PCM Color Television
R. Frank Quick · SMPTE Journal · 1980
A method is described for PCM encoding of the Y, I, and Q components of an NTSC signal in such a way that exact recovery of the components is possible, while compatibility with NTSC standards is approximately preserved. With this method, a digital decoder can separate Y, I, and Q exactly from the PCM signal; with a digital-to-analog conversion, the same PCM signal could be broadcast to standard analog NTSC receivers. The basis of the method is a block interpolation which increases the sampling rate of each component (to 4× subcarrier in the example presented here). Proper choice of the interpolation coefficients can produce a signal which approximates an NTSC standard signal. How good the approximation can be is an open question, but an example is given which demonstrates the concept and the design methods.