Video system for conveying digital and analog information
First Claim
1. A system for forming a composite signal by combining digital information with scanlines of an analog video signal generated by a line scanning device and for recovering the digital information from the composite signal, which comprises:
- means for combining digital information with the analog video signal at predetermiined locations along scanlines of the analog video signal to form said composite signal, the predetermined locations being substantially different as between a multiplicity of scanlines to substantially prevent visible deterioration of the image represented by the analog video scanlines; and
means for recovering the digital information by examining the composite signal at said predetermined locations along the scanlines to extract the digital information combined with the analog video signal.
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Accused Products
Abstract
A video system having a transmitter in which a composite signal is formed by combining digital information with scanlines of an analog video signal generated by a line scanning device, and a receiver in which the digital information is recovered. The digital information is combined with the analog video signal at predetermined locations along scanlines of the video signal, and these predetermined locations are varied in order to prevent visible deterioration of the video image. In the video receiver, the digital information is recovered by examining the composite signal at the predetermined locations to extract the digital information. Each bit of digital information to be conveyed is represented by a first pseudo-random digital pulse sequence (or its complement, depending on whether the data bit is 1 or 0) which is superimposed on a selected scanline of the analog video signal to form the composite signal. The digital information is recovered at the receiver by generating a second pseudo-random digital pulse sequence in synchronism with the first sequence, and by examining the composite signal at locations determined by the second digital pulse sequence to extract the digital information contained in the composite signal.
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Citations
51 Claims
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1. A system for forming a composite signal by combining digital information with scanlines of an analog video signal generated by a line scanning device and for recovering the digital information from the composite signal, which comprises:
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means for combining digital information with the analog video signal at predetermiined locations along scanlines of the analog video signal to form said composite signal, the predetermined locations being substantially different as between a multiplicity of scanlines to substantially prevent visible deterioration of the image represented by the analog video scanlines; and means for recovering the digital information by examining the composite signal at said predetermined locations along the scanlines to extract the digital information combined with the analog video signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 46)
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16. A method for forming a composite signal by combining digital information with scanlines of an analog video signal generated by a line scanning device and for recovering the digital information from the composite signal, which comprises:
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combining digital information with the analog video signal at predetermined locations along scanlines of the analog video signal to form said composite signal, the predetermined locations being substantially different as between a multiplicity of scanlines to substantially prevent deterioration of the image represented by the analog video scanlines; and recovering the digital information by examining the composite signal at said predetermined locations along the scanlines to extract the digital information from the composite signal. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 47)
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30. A method of combining digital information with an analog video signal generated by a line scanning device providing video frames and subsequently recovering said digital information, which comprises:
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generating a line count proportional to the number of line scans which have occurred within a video frame; generating a first pseudo-random digital pulse sequence and its complementary sequence synchronously with each line scan, the pulse distribution of said first pseudo-random digital pulse sequence and its complement being a function of said line count; selecting, for each scanline, either said first pseudo-random digital pulse sequence or said first complementary pulse sequence, depending upon the level of a selected bit of said digital information; superimposing each said selected first pulse sequence upon each corresponding line of said analog video signal to provide a composite line; for each first sequence generating a corresponding second pseudo-random digital sequence synchronized with said first sequence; coherently detecting each said composite line of said analog video signal by multiplying the composite line with the corresponding second pseudo-random digital sequence to provide a product signal; integrating the product singal of each coherent detection over at least a portion of the duration of the corresponding line; generating a signal representing the average level of each line of the composite signal; comparing each integrated signal with the signal representing the average level of said composite signal for each said corresponding line; determining whether said pseudo-random digital pulse sequence or said complementary sequence was superimposed upon each line of said video signal based upon whether each said integrated signal differs substantially from each average level; and generating a signal to indicate whether said pseudo-random digital pulse sequence or its complement was superimposed on each line of said analog video signal. - View Dependent Claims (48, 49)
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31. An apparatus for combining digital information with an analog video signal generated by a line scanning device providing video frames and subsequently recovering said digital information, which comprises:
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means for generating a line count proportional to the number of line scans which have occurred within a video frame; means for generating a first pseudo-random digital pulse sequence and its complementary sequence sychronously with each line scan, the pulse distribution of said first pseudo-random digital pulse sequence and its complement being a function of said line count; means for selecting, for each scanline, either said first pseudo-random digital pulse sequence or said first complementary pulse sequence, depending upon the level of a selected bit of said digital information; means for superimposing each said selected first pulse sequence upon each corresponding line of said analog video signal to provide a composite line; means for generating, for each first sequence, a second pseudo-random digital sequence synchronized with said first sequence; means for coherently detecting each said composite line of said analog video signal by multiplying the composite line with the corresponding second pseudo-random digital sequence to provide a product signal; means for integrating the product signal of each coherent detection over at least a portion of the duration of the corresponding line; means for generating a signal representing the average level of each line of the composite signal; means for comparing each integrated signal to the signal representing the average level of said composite signal for each corresponding line; means for determining whether said pseudo-random digital pulse sequence or said complementary sequence was superimposed upon each line of said video signal based upon whether each said integrated signal differs substantially from each average level for the corresponding line; and means for generating a signal to indicate whether said pseudo-random digital pulse sequence or its complement was superimposed on each line of said analog video signal. - View Dependent Claims (50, 51)
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- 32. A system for forming a composite signal by combining digital information with scanlines of an analog video signal generated by a line scanning device, which comprises means for combining digital information at predetermined locations along scanlines of the analog video signal to form said composite signal, the predetermined locations being substantially different as between a multiplicity of scanlines to substantially prevent visible deterioration of the image represented by the analog video scanlines.
- 38. A method for forming a composite signal by combining digital information with scanlines of an analog video signal generated by a line scanning device, which comprises combining digital information at predetermined locations along scanlines of the analog video signal to form said composite signal, the predetermined locations being subtantially different as between a multiplicity of scanlines to substantially prevent visible deterioration of the image represented by the analog video scanlines.
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44. An apparatus for recovering digital information from a composite signal containing video scanlines and digital information combined with scanline portions at predetermined locations along each of a multiplicity of scanlines, said predetermined locations being substantially different as between a multiplicity of scanlines to substantially prevent visible deterioration of the image represented by the analog video scanlines, which comprises means for examining the composite signal at said predetermined locations along the scanlines to extract the digital information, and means for providing the extracted digital information.
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45. A method for recovering digital information from a composite signal containing digital information at predetermined locations along scanlines of an analog video signal generated by a line scanning device, said predetermined locations being substantially different as between a multiplicity of scanlines to substantially prevent visible deterioration of the image represented by the analog video scanlines, which comprises examining the composite signal at said predetermined locations along the scanlines to extract the digital information, and providing an indication of the extracted digital information.
Specification