Statistical Word Synchronization in PCM Transmission of TV Signals

Word synchronization in PCM of TV signals is more important than that of audio signals, since often a single channel of TV signals is transmitted independently. For this purpose, new word synchronization is proposed, where the statistical property of TV signals is utilized instead of adding a bit for synchronization. The property is that a more significant bit in PCM does not change word by word as frequently as a less significant bit, because of the correlation between adjacent picture elements, i.e., sampled values or words. Mathematical calculation shows that the average time between misframes is as long as 10⁴years and the average recovery time is less than several lines when a 4-bit reversible counter for synchronization is used in transmitting 500-kHz narrow-band TV-phone signals.