EP0341801A2
Expired / Lapsed
EP
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Video scrambling systems
Assignee: PAYVIEW Ltd
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Filing: 1986-10-24
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Granted: —
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Expires: 2006-10-24
Abstract
Abstract A multimode scrambling system for video signal transmission systems is described. The system provides for baseband video scrambling controlled by a central originating computer facility. The scrambling of each field of a video changes on a per field basis. The video signal is scrambled in several modes including vertical interval scrambling, alternate line inversion, bogus sync pulse generation, video compression and video offset techniques. A scrambling sequence is sent by a unique algorithm, sent during the vertical interval to each system decoder. The algorithm is reordered for each of a plurality of fields of the video signal and the reordering position is identified by a unique synchronization pulse transmitted during the vertical interval of the video signal. Additional security measures are provided to inhibit a subscriber from avoiding a transmitted disable command, or an attempt to invade the subscriber decoder mechanical packaging security.
Inventors
- 👤 John Robert Thompson
- 👤 Curtis Joseph Hunting
- 👤 Ronald K. Masson
- 👤 Craig Evan Trivelpiece
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 16:35
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/167; H04N7/1675; H04N7/171
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
121 words
In a system for scrambling a video signal, an apparatus for transmitting a signal identifying one of a plurality of scrambled sequences comprising: means for generating during a vertical blanking interval of said video signal at least three unique horizontal synchronization pulse having a pulse width different from the pulse width of a plurality of remaining horizontal synchronization pulses, said unique pulses identifying specific lines of each field of said video signal; and means for inserting two of said generated synchronization pulses at the beginning of two lines of said video signal vertical interval, said two lines being the same for every transmitted field, and inserting a third of said unique pulses at a line number which identifies a scrambling sequence.
Claim 2
Dependent Claim
121 words
In a system for scrambling a video signal, an apparatus for transmitting a signal identifying one of a plurality of scrambled sequences comprising: means for generating during a vertical blanking interval of said video signal at least three unique horizontal synchronization pulse having a pulse width different from the pulse width of a plurality of remaining horizontal synchronization pulses, said unique pulses identifying specific lines of each field of said video signal; and means for inserting two of said generated synchronization pulses at the beginning of two lines of said video signal vertical interval, said two lines being the same for every transmitted field, and inserting a third of said unique pulses at a line number which identifies a scrambling sequence.
Claim 3
Dependent Claim
26 words
The scrambling system of claim 1 wherein said two unique synchronization pulses are inserted at the beginning of lines 1 and 10 of each vertical interval.
Claim 4
Dependent Claim
21 words
The scrambling system of claim 2 wherein said third unique pulse is located at the beginning of any of lines 10-17.
Claim 5
Dependent Claim
120 words
In a system for scrambling and descrambling a video signal, in accordance with one of a plurality of scrambling algorithms, means for transmitting to a receiving station the identity of a scrambling sequence comprising: means for inserting during the vertical interval of a field of said video signal a first group of horizontal synchronization pulses at predetermined line numbers having a width greater than the remaining synchronization pulses; means for inserting a second group of synchronization pulses of a pulse width less than the width of said synchronization pulses of a predetermined number of lines between said predetermined lines, said predetermined line numbers identifies one of said scrambling sequences; and means for transmitting said video signal to said receiving stations.
Claim 6
Dependent Claim
120 words
In a system for scrambling and descrambling a video signal, in accordance with one of a plurality of scrambling algorithms, means for transmitting to a receiving station the identity of a scrambling sequence comprising: means for inserting during the vertical interval of a field of said video signal a first group of horizontal synchronization pulses at predetermined line numbers having a width greater than the remaining synchronization pulses; means for inserting a second group of synchronization pulses of a pulse width less than the width of said synchronization pulses of a predetermined number of lines between said predetermined lines, said predetermined line numbers identifies one of said scrambling sequences; and means for transmitting said video signal to said receiving stations.
Claim 7
Dependent Claim
173 words
In a system for scrambling and descrambling video signals, wherein a plurality of video lines are inverted in accordance with one of a series of scrambling sequences, a method for sending and reordering a decoding signal, comprising: inserting during each field of said video signal at a plurality of predetermined line numbers horizontal synchronization pulses which are greater in width than the remaining synchronization pulses in said video signal; the position of said pulses identifying one of a series of said scrambling sequences; inserting for a plurality of lines between said horizontal synchronization pulses a number of synchronization pulses of a different width; transmitting to a receiving station said video signal; detecting the width of each of said horizontal synchronization pulses received at said receiving station whereby said predetermined line numbers are identified; storing in a predetermined order at said receiving station each of said scrambling sequences; identifying one of said stored scrambling sequences by said predetermined line numbers; and inverting lines of said video signal in accordance with said identified scrambling sequence.
Claim 8
Dependent Claim
173 words
In a system for scrambling and descrambling video signals, wherein a plurality of video lines are inverted in accordance with one of a series of scrambling sequences, a method for sending and reordering a decoding signal, comprising: inserting during each field of said video signal at a plurality of predetermined line numbers horizontal synchronization pulses which are greater in width than the remaining synchronization pulses in said video signal; the position of said pulses identifying one of a series of said scrambling sequences; inserting for a plurality of lines between said horizontal synchronization pulses a number of synchronization pulses of a different width; transmitting to a receiving station said video signal; detecting the width of each of said horizontal synchronization pulses received at said receiving station whereby said predetermined line numbers are identified; storing in a predetermined order at said receiving station each of said scrambling sequences; identifying one of said stored scrambling sequences by said predetermined line numbers; and inverting lines of said video signal in accordance with said identified scrambling sequence.
Claim 9
Independent Claim
124 words
A system for scrambling a video signal with a different scrambling sequence for each field of said video signal comprising: means for inverting each of a plurality of video lines in accordance with one of a plurality of scrambling sequences; means for transmitting during a vertical interval of said video signal a unique pulse having a position in said vertical field which identifies said one of a plurality of scrambling sequences; means for receiving said transmitted video signal including: means for detecting the position of said unique pulse from a received video signal whereby one of a plurality of scrambling sequences is identified; and means for reinverting said video signal in accordance with said identified scrambling sequence whereby a descrambled video signal is produced.
Claim 10
Independent Claim
124 words
A system for scrambling a video signal with a different scrambling sequence for each field of said video signal comprising: means for inverting each of a plurality of video lines in accordance with one of a plurality of scrambling sequences; means for transmitting during a vertical interval of said video signal a unique pulse having a position in said vertical field which identifies said one of a plurality of scrambling sequences; means for receiving said transmitted video signal including: means for detecting the position of said unique pulse from a received video signal whereby one of a plurality of scrambling sequences is identified; and means for reinverting said video signal in accordance with said identified scrambling sequence whereby a descrambled video signal is produced.
Claim 11
Dependent Claim
72 words
The system of scrambling a video signal of claim 6 further comprising: means for transmitting a scrambling algorithm signal during the vertical interval of said video signal, said scrambling algorithm identifying one plurality of scrambling sequences from another plurality of scrambling sequences; and, means for reinverting each video line of a field in accordance with one of said scrambling sequences identified by the position of said unique pulse and said scrambling algorithm.
Claim 12
Independent Claim
158 words
A system for scrambling a video signal which includes a plurality of fields of line information, each field separated by a vertical interval, comprising: means for transmitting during said vertical interval data identifying a scrambling algorithm, said scrambling algorithm specifying a plurality of scrambling sequences for a plurality of fields of said video signal; means for inserting a unique pulse of a specified duration at a location in said vertical interval which identifies one of said scrambling sequences; means for decoding said descrambling algorithm signal and generating the identity of each of said plurality of scrambling sequences from said algorithm; means for detecting the position of said unique pulse in said vertical interval whereby one of said scrambling sequences are identified; and means for descrambling each of said video signal fields in accordance with an identified sequence, said sequence changing in subsequent fields in accordance with the position of each newly received vertical interval containing said unique pulse.
Claim 13
Independent Claim
158 words
A system for scrambling a video signal which includes a plurality of fields of line information, each field separated by a vertical interval, comprising: means for transmitting during said vertical interval data identifying a scrambling algorithm, said scrambling algorithm specifying a plurality of scrambling sequences for a plurality of fields of said video signal; means for inserting a unique pulse of a specified duration at a location in said vertical interval which identifies one of said scrambling sequences; means for decoding said descrambling algorithm signal and generating the identity of each of said plurality of scrambling sequences from said algorithm; means for detecting the position of said unique pulse in said vertical interval whereby one of said scrambling sequences are identified; and means for descrambling each of said video signal fields in accordance with an identified sequence, said sequence changing in subsequent fields in accordance with the position of each newly received vertical interval containing said unique pulse.
Claim 14
Dependent Claim
18 words
The system of claim 8 wherein said scrambling sequences identify lines of said video signal which are inverted.
Claim 15
Dependent Claim
34 words
The system of claim 9 wherein each scrambling sequence comprises a plurality of alternate inverted lines of said video signal, the beginning line of each sequence changing for different fields of said video signal.
Claim 16
Independent Claim
168 words
A system for descrambling a video signal including false synchronization pulses are inserted in the video signal, an offset added to said video signal whereby active portions of said video signal are biased to below a black level, said video signal including during a specified line of said video signal, a reference black level and a white level, comprising: means for sampling said video signal reference black level and white level whereby first and second video signal reference levels are produced; buffer amplifier means for receiving said video signal and clamping said video signal at a level proportional to said black level whereby said video signal is removed; means for detecting the pedestal edge of each horizontal blanking interval, and generating a sync pulse synchronized with said detected pedestal edge having a leading and falling edge of a normal descrambled video signal sync pulse; means for inserting said synchronization pulse into said video signal in place of said false synchronization pulses whereby said video signal synchronization is restored.
Claim 17
Independent Claim
168 words
A system for descrambling a video signal including false synchronization pulses are inserted in the video signal, an offset added to said video signal whereby active portions of said video signal are biased to below a black level, said video signal including during a specified line of said video signal, a reference black level and a white level, comprising: means for sampling said video signal reference black level and white level whereby first and second video signal reference levels are produced; buffer amplifier means for receiving said video signal and clamping said video signal at a level proportional to said black level whereby said video signal is removed; means for detecting the pedestal edge of each horizontal blanking interval, and generating a sync pulse synchronized with said detected pedestal edge having a leading and falling edge of a normal descrambled video signal sync pulse; means for inserting said synchronization pulse into said video signal in place of said false synchronization pulses whereby said video signal synchronization is restored.
Claim 18
Dependent Claim
21 words
The system of claim 11 further comprising means for inverting alternate lines of a video signal produced by said buffer amplifier.
Claim 19
Dependent Claim
30 words
The apparatus of claim 11 wherein said horizontal synchronization pulses have an amplitude level which is scaled from the level of said white signal and black level signal reference samples.
Claim 20
Dependent Claim
83 words
In a vidoe scrambling system wherein a video signal is scrambled in a plurality of different modes, including extending horizontal synchronization pulse amplitudes and establishing said video signal at a level which produces an opaque picture when viewed on a television receiver, a decoder circuit comprising means for removing said horizontal synchronization pulses and replacing said removed pulses with horizontal synchronization pulses of a normal amplitude, and means for clamping said video signal at a reference level which renders said video signal visible.
Claim 21
Dependent Claim
83 words
In a vidoe scrambling system wherein a video signal is scrambled in a plurality of different modes, including extending horizontal synchronization pulse amplitudes and establishing said video signal at a level which produces an opaque picture when viewed on a television receiver, a decoder circuit comprising means for removing said horizontal synchronization pulses and replacing said removed pulses with horizontal synchronization pulses of a normal amplitude, and means for clamping said video signal at a reference level which renders said video signal visible.
Claim 22
Dependent Claim
43 words
The decoder circuit of claim 14 further comprising: means for detecting both a white sample level and black sample level contained in said video signal; and means for generating replacement synchronization pulses having an amplitude proportional to said white and black sample level.
Claim 23
Dependent Claim
22 words
The decoder circuit of claim 14 further comprising a reference level detection circuit for determining said reference level from said video signal.
References Cited (Backward Citations)
No citation records indexed.
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