Protected television signal distribution system
First Claim
1. In combination in video distribution apparatus;
- signal originating means including means for transmitting a picture carrier selectively modulated in amplitude to reduce vertical and horizontal synchronizing information relative to video picture information, and means for transmitting a sound carrier modulated in amplitude with horizontal synchronizing pulse timing information except during the vertical synchronizing interval and a digital video tag interleaved with said horizontal synchronizing pulse timing information and at least one receiver coupled to said signal originating means for receiving said picture and sound carriers, each of said receivers including authorization register means, sound carrier amplitude demodulator means for recovering said horizontal synchronizing pulse timing information and said digital video tag, vertical detector means connected to said sound carrier amplitude demodulator means for recovering vertical synchronizing timing from the absence of said horizontal synchronizing pulse timing information on said sound carrier during said vertical synchronizing interval, authorization comparator means connected to said digital video tag recovering means and said authorization register means for selectively permitting video reception, and means enabled by said authorization comparator means for increasing the amplitude of said received modulated picture carrier during said horizontal and vertical synchronizing periods relative to said video picture information.
2 Assignments
0 Petitions
Accused Products
Abstract
A television signal distribution system protects outgoing programs from unauthorized reception; and marks or tags the conveyed signals with a digital word identifying the class of viewers authorized to receive the program ("level of service"). Basic encription is accomplished by effectively suppressing the horizontal and vertical synchronizing information. Horizontal sync information, and the program-characterizing level of service word which is interleaved in time with prescribed horizontal sync pulses, is distributed via pulse amplitude modulation of the audio carrier.
At subscriber receiving stations, the sound carrier amplitude modulation is recovered to permit level of service authorization verification; and to reconstitute the video carrier to receivable form by an amplitude modulation which is the inverse of the sync-suppressing modulation of the head end.
In accordance with one feature of the present invention, a further data channel may be employed to very subscriber service authorizations--as to permit pay-per-view billing.
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Citations
15 Claims
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1. In combination in video distribution apparatus;
- signal originating means including means for transmitting a picture carrier selectively modulated in amplitude to reduce vertical and horizontal synchronizing information relative to video picture information, and means for transmitting a sound carrier modulated in amplitude with horizontal synchronizing pulse timing information except during the vertical synchronizing interval and a digital video tag interleaved with said horizontal synchronizing pulse timing information and at least one receiver coupled to said signal originating means for receiving said picture and sound carriers, each of said receivers including authorization register means, sound carrier amplitude demodulator means for recovering said horizontal synchronizing pulse timing information and said digital video tag, vertical detector means connected to said sound carrier amplitude demodulator means for recovering vertical synchronizing timing from the absence of said horizontal synchronizing pulse timing information on said sound carrier during said vertical synchronizing interval, authorization comparator means connected to said digital video tag recovering means and said authorization register means for selectively permitting video reception, and means enabled by said authorization comparator means for increasing the amplitude of said received modulated picture carrier during said horizontal and vertical synchronizing periods relative to said video picture information.
- View Dependent Claims (2, 3, 4, 5, 6)
- 7. In combination in receiver means for receiving a composite transmitted television wave comprising a picture carrier selectively modulated in amplitude to reduce vertical and horizontal synchronizing information relative to video picture information, and a sound carrier modulated in amplitude with horizontal synchronizing pulse timing information except during the vertical synchronizing interval and a digital video tag interleaved with said horizontal synchronizing pulse timing information, said receivers including authorization register means, sound carrier amplitude demodulator means for recovering said horizontal synchronizing pulse timing information and said digital video tag, vertical detector means connected to said sound carrier amplitude demodulator means for recovering vertical synchronizing timing from the absence of said horizontal synchronizing pulse timing information on said sound carrier, authorization comparator means connected to said digital video tag recovering means and said authorization register means for selectively permitting video reception, and means enabled by said authorization comparator means for increasing the amplitude of said received modulated picture carrier during said horizontal and vertical synchronizing periods relative to said video picture information.
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10. In combination in video distribution apparatus;
- signal originating means including means for transmitting a picture carrier selectively modulated in amplitude to reduce vertical and horizontal synchronizing information relative to video picture information, and means for transmitting a sound carrier modulated in amplitude with horizontal synchronizing pulse timing information except during the vertical synchronizing interval; and
not bearing vertical interval modulation; and
at least one receiver coupled to said signal originating means for receiving said picture and sound carriers, each of said receivers including sound carrier amplitude demodulator means for recovering said horizontal synchronizing pulse timing information, vertical detector means connected to said sound carrier amplitude demodulator means for recovering vertical synchronizing timing from the absence of said horizontal synchronizing pulse timing information on said sound carrier, and means for increasing the amplitude of said received modulated picture carrier during said horizontal and vertical synchronizing periods relative to said video picture information. - View Dependent Claims (11, 12, 13)
- signal originating means including means for transmitting a picture carrier selectively modulated in amplitude to reduce vertical and horizontal synchronizing information relative to video picture information, and means for transmitting a sound carrier modulated in amplitude with horizontal synchronizing pulse timing information except during the vertical synchronizing interval; and
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14. In combination in receiver means for receiving a composite transmitted wave comprising a picture carrier selectively modulated in amplitude to reduce vertical and horizontal synchronizing information relative to video picture information, and a sound carrier modulated in amplitude with horizontal synchronizing pulse timing information except during the vertical synchronizing interval;
- and not bearing vertical interval modulation;
said receiver means including sound carrier amplitude demodulator means for recovering said horizontal synchronizing pulse timing information, vertical detector means connected to said sound carrier amplitude demodulator means for recovering vertical synchronizing timing from the absence of said horizontal synchronizing pulse timing information on said sound carrier, and means for increasing the amplitude of said received modulated picture carrier during said horizontal and vertical synchronizing periods relative to said video picture information. - View Dependent Claims (15)
- and not bearing vertical interval modulation;
Specification