EP0323258A2
Expired / Lapsed
EP
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Communications distribution system
Assignee: Arris Technology Inc
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Filing: 1988-12-29
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Granted: —
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Expires: 2008-12-29
Abstract
Abstract A video distribution system (e.g., CATV or MATV) employs at least one channel having a reception-defeating jamming signal which changes frequency periodically or, preferably, randomly. The signal originating head end distributes information characterizing the operative frequency of the jamming wave. At controller apparatus for authorized viewers, the jamming frequency specifying data is employed on a frequency agile basis to heterodyne the protected channel into a proper (fixed) frequency relationship with a notch band suppression filter to remove the jamming signal. The secure channel with the jamming wave removed is then again shifted to its original or other intended frequency to permit normal reception either directly by a standared television receiver, or via a frequency converter.
Inventors
- 👤 David E. Wachob
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 16:44
CPC Classifications
H; H04; H04K; H04K3/00; H04K3/80; H04K3/82; H04K3/825; H04K3/20; H04K3/28; H04K3/40; H04K3/42; H04N; H04N7/00; H04N7/16; H04N7/166; H04N7/167; H04K2203/00; H04K2203/10; H04K2203/14
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
45 words
A communications system wherein, for the purpose of inhibiting unauthorized reception of transmitted communications, a variable characteristic jamming signal together with information representative thereof is included in transmitted signals and authorized receivers have means responsive to reception of such information for removing the jamming signal.
Claim 2
Dependent Claim
45 words
A communications system wherein, for the purpose of inhibiting unauthorized reception of transmitted communications, a variable characteristic jamming signal together with information representative thereof is included in transmitted signals and authorized receivers have means responsive to reception of such information for removing the jamming signal.
Claim 3
Dependent Claim
105 words
In combination in apparatus for electronically restoring a video program which includes an in-band jamming wave characterized by a time varying frequency, means for receiving the jammed video program, a band reject filter, heterodyning means haviang first and second inputs and an output connected to said band reject filter; said receiving means coupling the video program having the variable frequency jamming wave to said first input of said heterodyning means, and means for supplying to said second input of said heterodyning means a signal of time varying frequency appropriate to heterodyne the changing frequency of the jamming signal to that of the band reject filter.
Claim 4
Dependent Claim
105 words
In combination in apparatus for electronically restoring a video program which includes an in-band jamming wave characterized by a time varying frequency, means for receiving the jammed video program, a band reject filter, heterodyning means haviang first and second inputs and an output connected to said band reject filter; said receiving means coupling the video program having the variable frequency jamming wave to said first input of said heterodyning means, and means for supplying to said second input of said heterodyning means a signal of time varying frequency appropriate to heterodyne the changing frequency of the jamming signal to that of the band reject filter.
Claim 5
Dependent Claim
25 words
A combination as in claim 2, further comprising second heterodyning means for varying the output frequency of the signal passing through said band reject filter.
Claim 6
Dependent Claim
15 words
A combination as in claim 3, wherein said band reject filter is of fixed frequency.
Claim 7
Dependent Claim
20 words
A combination as in claim 3, wherein said time varying frequency signal supplying means comprises frequency agile frequency synthesizer means.
Claim 8
Dependent Claim
19 words
A combination as in claim 5, further comprising head end means for supplying the jamming wave including video program.
Claim 9
Dependent Claim
51 words
A combination as in claim 6, wherein said head end means includes means for communicating the operative frequency of said jamming wave, said restoring apparatus further comprising means responsive to the jamming wave frequency supplied by said jamming wave frequency communicating means for controlling the frequency of said frequency synthesizer means.
Claim 10
Dependent Claim
45 words
A combination as in claim 5, wherein said band reject filter has a rejection frequency z , the jamming wave has a frequency j ′, and said frequency agile frequency synthesizer means an output frequency z+j′, where z and j ′ are independent positive numbers.
Claim 11
Dependent Claim
34 words
A combination as in claim 2, wherein said restoring apparatus further includes first band pass filter having sufficient frequency capacity to pass said video program connected to said first input of said heterodyning means.
Claim 12
Dependent Claim
51 words
A combination as in claim 9, wherein said restoring apparatus further comprises additional heterodyne means haviang an input connected to said band reject filter and an output, and second band pass filter means having sufficient frequency capacity to pass said video program connected to said output of said additional heterodyne means.
Claim 13
Dependent Claim
20 words
A combination as in claim 2, further comprising viewer-actuated demand signalling means for selectively enabling operation of said heterodyne means.
Claim 14
Dependent Claim
29 words
A combination as in claim 6, wherein said head end means supplies plural video programs having a jamming wave of varying frequency in a time-changing one of said programs.
Claim 15
Dependent Claim
94 words
In apparatus for recovering an electronic signal which includes a frequency varying jamming signal, a band reject filter of fixed frequency, heterodyning means having first and second inputs and an output connected to said fixed frequency filter; means for supplying the signal having the variable frequency jamming signal to said first input of said heterodyning means, and means for supplying to said second input of said heterodyning means a wave of time varying frequency of appropriate value to shift the then-obtaining frequency of the jamming signal to that of the fixed band reject filter.
Claim 16
Dependent Claim
94 words
In apparatus for recovering an electronic signal which includes a frequency varying jamming signal, a band reject filter of fixed frequency, heterodyning means having first and second inputs and an output connected to said fixed frequency filter; means for supplying the signal having the variable frequency jamming signal to said first input of said heterodyning means, and means for supplying to said second input of said heterodyning means a wave of time varying frequency of appropriate value to shift the then-obtaining frequency of the jamming signal to that of the fixed band reject filter.
Claim 17
Dependent Claim
25 words
A combination as in claim 13, further comprising second heterodyning means for varying the output frequency of the signal passing through said band reject filter.
Claim 18
Dependent Claim
18 words
A combination as in claim 14, wherein said heterodyne wave supplying means comprises frequency agile frequency synthesizer means.
Claim 19
Dependent Claim
19 words
A combination as in claim 15, further comprising signal origination means for supplying the jamming signal including electronic signal.
Claim 20
Dependent Claim
50 words
A combination as in claim 16, wherein said signal origination means includes means for communicating the operative frequency of said jamming signal, said recovering apparatus further comprising means responsive to the jamming signal frequency supplied by said jamming signal communicating means for controlling the frequency of said frequency synthesizer means.
References Cited (Backward Citations)
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