System for transparent transmission and reception of a secondary data signal with a video signal in the video band
First Claim
1. A signal processor for combining data in the same communications channel as a video signal for an image, the video signal having a video bandwidth and having horizontal and vertical blanking interval defined by sync pulses and an active video intervals between blanking intervals, the video signal having luminance and chrominance information frequency interleaved with each other, the data being uncorrelated to the image, the signal processor comprising:
- means for receiving a video signal and the data signal;
means for detecting the frequency of at least one of the blanking and active video intervals and the sync pulses; and
means responsive to the detecting means for modulating the data within the video bandwidth with carrier; and
combining the modulated data with the video signal without phase inversion of the data such that the modulated data signal is present during at least some parts of each active video interval but not during the blanking intervals such that the modulated data information is frequency interleaved with both the chrominance and the luminance information such that the phase of the data remains substantially unaltered between successive fields.
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Accused Products
Abstract
Signal processors for permitting the transparent, simultaneous transmission and reception of a secondary data signal with a video signal in the video band is disclosed. The signal processor in the transmitter rasterizes the data at the horizontal scanning rate and modulates the data with a data carrier at a non-integral multiple of the horizontal scanning rate to obtain frequency interleaving. The data is transmitted during the active video portion of each video line.
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Citations
45 Claims
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1. A signal processor for combining data in the same communications channel as a video signal for an image, the video signal having a video bandwidth and having horizontal and vertical blanking interval defined by sync pulses and an active video intervals between blanking intervals, the video signal having luminance and chrominance information frequency interleaved with each other, the data being uncorrelated to the image, the signal processor comprising:
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means for receiving a video signal and the data signal; means for detecting the frequency of at least one of the blanking and active video intervals and the sync pulses; and means responsive to the detecting means for modulating the data within the video bandwidth with carrier; and combining the modulated data with the video signal without phase inversion of the data such that the modulated data signal is present during at least some parts of each active video interval but not during the blanking intervals such that the modulated data information is frequency interleaved with both the chrominance and the luminance information such that the phase of the data remains substantially unaltered between successive fields. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for transmitting data other than a video signal in the same communications channel as a color video signal comprised of chrominance and luminance information frequency interleaved with each other being transmitted in a given frequency band, the color video signal having a video bandwidth and active and blanking intervals with a sync frequency, and the video signal, and the data being uncorrelated with respect to each other, the method comprising:
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detecting the active video intervals; and transmitting the data at frequencies within the band substantially centered around quarter non-integral multiples of the sync frequency without phase inversion of the data during at least some of the active video intervals and the transmitting the data further includes blanking the data signal other than during the active video .period whereby the data signal is rasterized. - View Dependent Claims (9, 10)
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11. A system for combining a secondary data signal with a color frequency interleaved video signal having audio information in a frequency band above frequency bands of luminance and chrominance information interleaved with each other, horizontal sync pulses at a predetermined rate and gaps in the video frequency spectra, the system comprising:
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a timing circuit responsive to the sync pulses, the timing circuit producing a data carrier at a frequency that is an odd quarter non-integral multiple of the rate; a combiner having at least two inputs; a video portion providing the primary video signal to one input of the combiner; a secondary data portion providing a second input to the combiner; a blanking interval detector producing a blanking signal indicating the time periods of the blanking interval; the secondary data portion including; a data buffer receiving the secondary data and providing rasterized data at an output based upon the blanking signal and the secondary data without altering the phase of the secondary data substantially; a modulator for providing a modulated data signal responsive to the data carrier and the output of the data buffer, the modulated data signal being coupled to the second input of the combiner such that the spectra of the modulated data signal lies substantially within the gaps of the video spectra such that the modulated data is only present during the blanking intervals. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A signal processor for separating a data signal from a rasterized video signal having horizontal and vertical blanking intervals at predetermined intervals and having chrominance and luminance information frequency interleaved in a bandwidth and the data information being contained substantially in an unused portion of the same bandwidth, the processor comprising:
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a timing circuit generating a timing signal at a predetermined frequency based upon the rate of the horizontal intervals; a band pass filter passing as an output the frequencies for the data signal; and a data separator responsive to the timing signal and the output of the filter for outputting the data signal at a data rate above about 100 kilobits per second without altering the phase of the data signal substantially. - View Dependent Claims (22, 23, 24, 26)
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25. A system for adding a secondary data signal to a primary video signal blanking intervals defined by sync pulses and a frequency baseband, the data signal being uncorrelated to the video signal, the system comprising:
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means for detecting at least some of the sync pulses in the video signal; means for modulating a data carrier within the baseband based upon the detected sync pulses with the data without altering substantially the phase relationship of the data to provide a modulated data signal having the frequency band of the modulated data carrier at least partially overlapping the video band of the video signal; and means for combining the modulated data signal with the video signal such that the data signal is transparent to a receiver designed to receive the video signal.
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27. An apparatus for injection of a data signal into a rasterized, frequency interleaved, color baseband video signal having blanking intervals a color carrier located in an upper half of the video bandwidth and a bandwidth with an upper limit, the apparatus comprising:
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a rasterizer providing blanking intervals in the data signal to form a rasterized data signal; a carrier generator generating a data carrier to modulate the rasterized data signal to produce a modulated, rasterized data signal without phase inversion of the carrier or the data, the frequency of the carrier lying within the color baseband video signal; a filter to attenuate at least some of the frequencies between the video carrier and the data carrier to produce a filtered video signal; and a combiner to inject the modulated, rasterized data signal into the filtered video signal at a sufficiently low level of injection such that the data creates no visible artifacts on the screen of a television receiver. - View Dependent Claims (28, 29, 30, 31)
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32. A method for injecting data other than a video signal in the same communications channel as a color video signal having a given frequency baseband with color and luminance portions, the video signal having a video bandwidth and active and blanking intervals, the color portion and luminance portion of the video signal being frequency interleaved at evenly spaced frequency gaps with the luminance portion and the video signal and the data being uncorrelated with respect to each other, the method comprising:
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detecting the active video intervals; and injecting data having a data rate of greater than one hundred kilobits per second at frequencies within the baseband during at least some of the active video intervals but not during the blanking intervals and without causing visibly discernable interference effects at the receiver. - View Dependent Claims (33, 34)
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35. A system for interleaving a secondary data signal with a color video signal having color and luminance portions of the video signal spaced equidistant from each other to provide a frequency interleaved signal and having horizontal sync pulses at a predetermined rate, the system comprising:
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a timing circuit responsive to the sync pulses, the timing circuit producing a data carrier at a frequency that is a non-integral multiple of the predetermined rate and a timing signal at an integral multiple or submultiple of the rate; a combiner having at least two inputs; a video portion providing the primary video signal to one input of the combiner; a secondary data portion providing a second input to the combiner; a blanking interval detector producing a blanking signal indicating the time periods of the blanking interval; the secondary data portion including; a data buffer receiving the secondary data and providing rasterized data at an output based upon the blanking signal and the secondary data; a modulator for providing a modulated data signal responsive to the data carrier, the modulated data signal being coupled to the second input of the combiner. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. A signal processor for separating a data signal frequency interleaved with a rasterized video signal having horizontal and vertical blanking intervals at predetermined intervals, the processor comprising
a timing circuit generating a timing signal at a predetermined frequency based upon the rate of the horizontal and vertical intervals; -
a band pass/comb filter passing as an output the frequencies for the data signal; a data separator responsive to the timing signal and the output of the filter for outputting the data signal.
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Specification