Abstract: In the present invention, an ancillary code is added to a composite video signal in its active video portion. The ancillary code may be spread over several frequencies and summed at the output of a decoder to enhance the legibility of the ancillary code at the output of the decoder. Frequency-stepping may be used to add the ancillary code at ones of a plurality of selected frequencies within the bandwidth of the composite video signal. The ancillary code may be hierarchically apportioned between respective uniquely specified sequential segments corresponding to many distribution points of the composite television signal. This hierarchical ancillary code may be frequency-interleaved between harmonics of the horizontal sync frequency of the composite video signal. The ancillary code may be redundantly added above and below the roll-off frequency of a VCR.

Abstract: 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.

Abstract: An ancillary signal is injected into a program signal within the frequency band normally occupied by the program signal alone. The program signal includes a modulated carrier having a carrier frequency and a low energy density portion of the frequency band. The ancillary signal is selectively added at an injection frequency within the lower energy density portion of the frequency band so that the injection frequency is locked to the carrier frequency and to the frequency of a local oscillator.