Video and data co-channel communication system

摘要

In the present invention, ancillary data is modulated onto a carrier frequency which is within a low energy density portion of a frequency band of a video signal, and the modulated carrier data is combined with the video signal so that the modulated carrier is in an overscan region of the video signal. The ancillary data may be spread over several frequencies and summed at the output of a decoder to enhance the legibility of the ancillary data at the output of the decoder. Frequency-stepping may be used to add the ancillary data at ones of a plurality of selected frequencies within the frequency band of the video signal. The ancillary data may be hierarchically apportioned between respective uniquely specified sequential segments corresponding to many distribution points of the video signal. This hierarchical ancillary data may be frequency-interleaved between harmonics of the horizontal sync frequency of the video signal. The ancillary data may be redundantly added above and below the roll-off frequency of a VCR.