System and method for inserting and recovering an add-on data signal for transmission with a video signal
First Claim
1. A system for transmitting a data signal with a video signal, comprising:
- a first delay element receiving the data signal, the data signal being unrelated to the video signal, and producing a delayed data signal that is delayed a predetermined period of time from the data signal;
a first adder element adding the data signal and said delayed data signal to produce a first filtered signal having a plurality of spectral peaks with a spacing corresponding to spacing in an unused portion of the frequency spectrum of the video signal;
a modulator modulating a single unmodulated carder frequency with said first filtered signal to produce a modulated filtered signal, said carder frequency being selected to permit said first filtered signal to be inserted into said unused portion of the frequency spectrum of the video signal;
a second adder element adding said modulated filtered signal and the video signal to produce a modified video signal containing said modulated filtered signal with said first filtered signal inserted into said unused portion of the frequency spectrum of the video signal;
a transmitter transmitting said modified video signal;
a receiver receiving said transmitted modified video signal and processing said modified video signal to regenerate the video signal;
a separator circuit separating said modulated filtered signal from said transmitted modified video signal to reconstruct said first filtered signal; and
an inverse filter processing said reconstructed first filtered signal to recover the data signal, whereby the data signal is transmitted with the video signal and subsequently separated from the data signal in said receiver.
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Accused Products
Abstract
A system and method for inserting a data signal into a preexisting video signal in a transmitter so that the data signal is transmitted along with the video signal. The data signal is inserted into an unused portion of the video signal spectrum. The data signal is separated from the video signal in a receiver and may be used for any purpose, even purposes unrelated to the video signal. The data signal is filtered to create a filtered data signal having spectral characteristics that correspond to the unused portion of the video signal spectrum. The filtered signal modulates a carrier signal whose frequency is selected to permit direct insertion of the modulated filtered data signal into the video signal spectrum. In the receiver, the video signal is processed in a normal manner; and the data signal is undetected by normal television receivers. A signal separator separates the filtered data signal from the combined video signal, and an inverse filter recovers the original data signal. In one embodiment, a comb filter is used to generate the filtered data signal with 60 Hertz peaks. An inverse comb filter in the receiver recovers the original data signal. A recirculating buffer may also be used to generate the filtered data signal.
195 Citations
44 Claims
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1. A system for transmitting a data signal with a video signal, comprising:
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a first delay element receiving the data signal, the data signal being unrelated to the video signal, and producing a delayed data signal that is delayed a predetermined period of time from the data signal; a first adder element adding the data signal and said delayed data signal to produce a first filtered signal having a plurality of spectral peaks with a spacing corresponding to spacing in an unused portion of the frequency spectrum of the video signal; a modulator modulating a single unmodulated carder frequency with said first filtered signal to produce a modulated filtered signal, said carder frequency being selected to permit said first filtered signal to be inserted into said unused portion of the frequency spectrum of the video signal; a second adder element adding said modulated filtered signal and the video signal to produce a modified video signal containing said modulated filtered signal with said first filtered signal inserted into said unused portion of the frequency spectrum of the video signal; a transmitter transmitting said modified video signal; a receiver receiving said transmitted modified video signal and processing said modified video signal to regenerate the video signal; a separator circuit separating said modulated filtered signal from said transmitted modified video signal to reconstruct said first filtered signal; and an inverse filter processing said reconstructed first filtered signal to recover the data signal, whereby the data signal is transmitted with the video signal and subsequently separated from the data signal in said receiver. - View Dependent Claims (2, 3, 4, 5)
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6. A system for transmitting a data signal with a video signal, comprising:
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a first filter receiving the data signal and producing a filtered signal having a plurality of spectral peaks with spacing corresponding to spacing of an unused portion of the frequency spectrum of the video signal, said data signal being unrelated to the video signal; a modulator element modulating a single unmodulated carrier frequency with said filtered signal to produce a modulated filtered signal, said carrier frequency being selected to modulate said filtered signal into said unused portion of the frequency spectrum of the video signal to produce a modified video signal containing said modulated filtered signal with said filtered signal inserted into said unused portion of the frequency spectrum of the video signal; a signal separator processing, said modified video signal to recover said filtered signal; and a second filter receiving said recovered filtered signal from said signal separator to recover the data signal from said recovered filtered signal, whereby the data signal is inserted into said unused portion of the frequency spectrum of the video signal and subsequently recovered from the video signal. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A system for inserting a data signal into a video signal, comprising:
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a filter receiving the data signal and producing a filtered signal having a plurality of spectral peaks with spacing corresponding to spacing in an unused portion of the frequency spectrum of the video signal, said data signal being uncorrelated to the video signal; and a modulator element modulating a single unmodulated carrier frequency having a predetermined phase with said filtered signal to produce a modulated filtered signal, said carrier frequency being selected to modulate said filtered signal into said unused portion of the frequency spectrum of the video signal to produce a modified video signal containing said modulated filtered signal with said filtered signal inserted into said unused portion of the frequency spectrum of the video signal. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A system for recovering a data signal inserted into an unused portion of the frequency spectrum of an unrelated video signal, the data signal being filtered to generate a filtered signal having a plurality of spectral peaks with a spacing corresponding to spacing in an unused portion of the frequency spectrum of the video signal and modulated with a single unmodulated carrier frequency to generate a modulated data signal, the system comprising:
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a signal separator separating the modulated data signal from the unused portion of the frequency spectrum of the video signal; a demodulator coupled to said signal separator and demodulating the modulated data signal to recover the filtered signal, said demodulator having a single carrier frequency with a predetermined phase and a carrier frequency selected to correspond to the unused portion of the frequency spectrum of the video signal; and a receiver filter receiving said filtered signal from said demodulator to recover the data signal from the filtered signal, said recovered data signal being uncorrelated to the video signal, whereby the data signal is inserted into the unused portion of the frequency spectrum of the video signal and subsequently recovered from the video signal. - View Dependent Claims (28, 29, 30, 31)
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32. A method for transmitting a data signal with a video signal, comprising the steps of:
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filtering the data signal to produce a filtered signal having a plurality of spectral peaks with spacing corresponding to spacing of an unused portion of the frequency spectrum of the video signal, the data signal being independent of the video signal; modulating a single unmodulated carrier frequency with said filtered signal to produce a modulated filtered signal, said carrier frequency being selected to modulate said filtered signal into said unused portion of the frequency spectrum of the video signal to produce a modified video signal containing said modulated filtered signal with said filtered signal inserted into said unused portion of the frequency spectrum of the video signal; separating said filtered signal from said modified video signal; and inverse filtering said filtered signal separated by said signal separator to recover the data signal from said filtered signal. - View Dependent Claims (33, 34, 35, 36, 37)
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38. A method for inserting a data signal into a video signal, comprising the steps of:
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filtering the data signal to produce a filtered signal having a plurality of spectral peaks with spacing corresponding to spacing in an unused portion of the frequency spectrum of the video signal the data, signal being unrelated to the video signal; and modulating a single unmodulated carrier frequency having a predetermined phase with said filtered signal to produce a modulated filtered signal, said carrier frequency being selected to modulate said filtered signal into said unused portion of the frequency spectrum of the video signal to produce a modified video signal containing said modulated filtered signal with said filtered signal inserted into said unused portion of the frequency spectrum of the video signal. - View Dependent Claims (39, 40, 41, 42)
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43. A method for recovering a data signal inserted into an unused portion of the frequency spectrum of an unrelated video signal, the data signal being filtered to generate a filtered signal having a plurality of spectral peaks with a spacing corresponding to spacing in an unused portion of the frequency spectrum of the video signal and modulated with a single unmodulated carrier frequency to generate a modulated data signal, the method comprising the steps of:
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separating the modulated data signal from the unused portion of the frequency spectrum of the video signal; demodulating the modulated data signal separated from the unused portion of the spectrum of the video signal to recover the filtered signal, said step of demodulating using a single carrier frequency having a predetermined phase with said carrier frequency selected to correspond to said unused portion of the frequency spectrum of the video signal; and inverse filtering the filtered signal following said step of demodulating to recover the data signal from the filtered signal, said recovered data signal being uncorrelated to the video signal. - View Dependent Claims (44)
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Specification