Encryption/decryption process and apparatus for a multichannel television system

Claim 3

The method of claim 1, wherein said decrypting step includes the step of synchronizing the decryption of said channel signals with said common timing reference signal.

Claim 4

The method of claim 1, wherein said causing step includes the step of simultaneously amplitude modulating said channel signals in accordance with said predetermined encoding rule.

Claim 5

The method of claim 3, wherein said decrypting step includes the steps of: recovering said common timing reference signal; and simultaneously amplitude modulating, synchronous with said common timing reference signal, said channel signals in accordance with the inverse of said encoding rule.

Claim 6

The method of claim 1, wherein said causing step includes the step of simultaneously amplitude modulating said channel signals in accordance with said encoding rule.

Claim 7

The method of claim 5, wherein said decrypting step includes the steps of: recovering said common timing reference signal; and simultaneously amplitude modulating, synchronous with said common timing reference signal, said channel signals in accordance with the inverse of said encoding rule.

Claim 8

The method of claim 1, further comprising the step of adding authorization data to said common timing reference signal before distributing said common timing reference signal to said subscriber sites.

Claim 9

The method of claim 7, wherein said responding step includes extracting said authorization data from said common timing reference signal at each subscriber site and enabling or disabling said decrypting step in response to said authorization data.

Claim 10

The method of claim 1, further including modulating a selected channel signal with said common timing reference signal before distributing to said subscriber sites.

Claim 11

The method of claim 9, wherein said responding step includes extracting said common timing reference signal from said selected channel signal by demodulating said selected channel signal.

Claim 12

The method of claim 9, wherein said modulating step comprises frequency modulation.

Claim 13

The method of claim 11, wherein each channel signal is comprised of an audio component at a first carrier frequency and a video component at a second different carrier frequency and said frequency modulation does not alter the difference between said carrier frequencies.

Claim 14

Apparatus for distributing multiple video signals, each produced by a different video source at a system headend and each containing picture and synchronization components, to a plurality of subscriber sites located remote from said headend, the apparatus comprising: means at said headend for generating multiple carrier signals; means at said headend for modulating each of said carrier signals with a different one of said video signals to form multiple channel signals, all of said channel signals having their respective video signal synchronization components in time coincidence; means at said headend for generating a common timing reference signal synchronous with said time coincident synchronization components; means at said headend for causing each of said channels signals to be encrypted in accordance with a common predetermined encoding rule; means to data modulate a selected encoded channel signal in response to said common timing reference signal; means at said headend for distributing said multiple encrypted channels signals to said subscriber sites as a common RF signal; and means at each subscriber site responsive to said common timing reference signal for simultaneously decrypting all of said channel signals distributed thereto by operating upon said common RF signal with a single downconverter/decoder in accordance with the inverse of said encoding rule to recover multiple decrypted signals for direct simultaneous application to a conventional television receiver.

Claim 15

Apparatus for distributing multiple video signals, each produced by a different video source at a system headend and each containing picture and synchronization components, to a plurality of subscriber sites located remote from said headend, the apparatus comprising: means at said headend for generating multiple carrier signals; means at said headend for modulating each of said carrier signals with a different one of said video signals to form multiple channel signals, all of said channel signals having their respective video signal synchronization components in time coincidence; means at said headend for generating a common timing reference signal synchronous with said time coincident synchronization components; means at said headend for causing each of said channels signals to be encrypted in accordance with a common predetermined encoding rule; means to data modulate a selected encoded channel signal in response to said common timing reference signal; means at said headend for distributing said multiple encrypted channels signals to said subscriber sites as a common RF signal; and means at each subscriber site responsive to said common timing reference signal for simultaneously decrypting all of said channel signals distributed thereto by operating upon said common RF signal with a single downconverter/decoder in accordance with the inverse of said encoding rule to recover multiple decrypted signals for direct simultaneous application to a conventional television receiver.

Claim 16

The apparatus of claim 13, wherein said means for decrypting includes means for synchronizing the decryption of said channel signals with said common timing reference signal.

Claim 17

The apparatus of claim 13, wherein means for causing includes means for simultaneously amplitude modulating said channel signals in accordance with said predetermined encoding rule.

Claim 18

The apparatus of claim 15, wherein said means for decrypting includes: means for recovering said common timing reference signal; and means for simultaneously amplitude modulating, synchronous with said common timing reference signal, said channel signals in accordance with the inverse of said encoding rule.

Claim 19

The apparatus of claim 13, wherein said means for causing includes means for simultaneously amplitude modulating said channel signals in accordance with said encoding rule.

Claim 20

The apparatus of claim 17, wherein said means for decrypting includes: means for recovering said common timing reference signal; and means for simultaneously amplitude modulating, synchronous with said common timing reference signal, said channel signals in accordance with the inverse of said encoding rule.

Claim 21

The apparatus of claim 13, further comprising means for adding authorization data to said common timing reference signal before distributing said common timing reference signal to said subscriber sites.

Claim 22

The apparatus of claim 19, further comprising means for extracting said authorization data from said common timing reference signal at each subscriber site to enable or disable said decrypting means in response to said authorization data.

Claim 23

The apparatus of claim 13, further comprising means to modulate a selected channel signal with said common timing reference signal before distributing to said subscriber sites.

Claim 24

The apparatus of claim 21, wherein said decrypting means includes means to extract said common timing reference signal from said selected channel signal by demodulating said selected channel signal.

Claim 25

The apparatus of claim 21, wherein said modulation means modifies said selected channel signal using frequency modulation.

Claim 26

The method of claim 23, wherein each channel signal is comprised of an audio component at a first carrier frequency and a video component at a second different carrier frequency and said frequency modulation means does not alter the difference between said carrier frequencies.

Claim 27

Apparatus for distributing multiple video signals, each produced by a different video source at a system headend and each containing picture and synchronization components, to a plurality of subscriber sites located remote from said headend, the apparatus comprising: a video reference clock for generating a synchronizing signal; a plurality of frame synchronizers responsive to said synchronizing signal and said video signals for generating a plurality of time synchronized video signals; a plurality of IF modulators responsive to said time synchronized video signals for generating a plurality of modulated video signals; a plurality of encoders responsive to said synchronizing signal for removing said synchronization components from said modulated video signals to generate a plurality of encoded video signals; means to data modulate a selected encoded video signal in response to said synchronizing signal; and means to distribute said encoded video signals to a plurality of subscriber sites; and means at each subscriber site to simultaneously decode each of said encoded video signals by reinserting said synchronization components in response to said selected modulated video signal.

Claim 28

Apparatus for distributing multiple video signals, each produced by a different video source at a system headend and each containing picture and synchronization components, to a plurality of subscriber sites located remote from said headend, the apparatus comprising: a video reference clock for generating a synchronizing signal; a plurality of frame synchronizers responsive to said synchronizing signal and said video signals for generating a plurality of time synchronized video signals; a plurality of IF modulators responsive to said time synchronized video signals for generating a plurality of modulated video signals; a plurality of encoders responsive to said synchronizing signal for removing said synchronization components from said modulated video signals to generate a plurality of encoded video signals; means to data modulate a selected encoded video signal in response to said synchronizing signal; and means to distribute said encoded video signals to a plurality of subscriber sites; and means at each subscriber site to simultaneously decode each of said encoded video signals by reinserting said synchronization components in response to said selected modulated video signal.

Claim 29

The apparatus of claim 25, wherein said data modulation means is additionally responsive to authorization data.

Claim 30

The apparatus of claim 26, wherein said decoding means is enabled or disabled in response to said authorization data.

Claim 31

The apparatus of claim 25, wherein said modulating means uses frequency modulation.

Claim 32

The apparatus of claim 28, wherein each modulated video signal is comprised of an audio component at a first carrier frequency and a video component at a second different carrier frequency and said frequency modulation does not alter the difference between said carrier frequencies.

Claim 33

The apparatus of claim 25, wherein said decoding means comprises: receiving means to extract said synchronization signal from said selected modulated video signal; and means to phase lock said receiving means to said extracted synchronization signal.

Claim 34

The apparatus of claim 30, wherein said phase locking means comprises: an oscillator generating a clock frequency in responsive to a control signal; and a processor, executing software to control said receiving means, at a rate responsive to said clock frequency; said processor additionally being responsive to said extracted synchronization signal by altering said control signal.

Claim 35

Apparatus for distributing multiple video signals, each produced by a different video source at a system headend and each containing picture and synchronization components, to a plurality of subscriber sites located remote from said headend, the apparatus comprising: a video reference clock for generating a synchronizing signal; a plurality of frame synchronizers responsive to said synchronizing signal and said video signals for generating a plurality of time synchronized video signals; a plurality of encoders responsive to said synchronizing signal for removing said synchronization components from said video signals to generate a plurality of encoded video signals; a plurality of IF modulators responsive to said time synchronized video signals for generating a plurality of modulated encoded video signals; means to data modulate a selected encoded video signal in response to said synchronizing signal; and means to distribute said encoded video signals to a plurality of subscriber sites; and means at each subscriber site to simultaneously decode each of said encoded video signals by reinserting said synchronization components in response to said selected modulated video signal.

Claim 36

Apparatus for distributing multiple video signals, each produced by a different video source at a system headend and each containing picture and synchronization components, to a plurality of subscriber sites located remote from said headend, the apparatus comprising: a video reference clock for generating a synchronizing signal; a plurality of frame synchronizers responsive to said synchronizing signal and said video signals for generating a plurality of time synchronized video signals; a plurality of encoders responsive to said synchronizing signal for removing said synchronization components from said video signals to generate a plurality of encoded video signals; a plurality of IF modulators responsive to said time synchronized video signals for generating a plurality of modulated encoded video signals; means to data modulate a selected encoded video signal in response to said synchronizing signal; and means to distribute said encoded video signals to a plurality of subscriber sites; and means at each subscriber site to simultaneously decode each of said encoded video signals by reinserting said synchronization components in response to said selected modulated video signal.