Patent US3733431A successfully refreshed from Google Patents.
US3733431A
Expired / Lapsed
US
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Electronic communication apparatus employing encripted signal distribution
Assignee: —
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Filing: 1971-03-10
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Granted: 1973-05-15
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Expires: 1991-03-10
Abstract
Abstract Private programming information, e.g., television programs provided for a community antenna television signal distribution system (CATV) to supplement those programs received from local commercial television stations, are encripted by switching the private program signals between predetermined transmission channels at a low, preferably nonperiodic rate. A modulated pilot carrier is provided to communicate synchronizing information. A special signal recovery apparatus at the station of a private service subscriber recovers the special programming by effecting a switching procedure inverse to that performed upon signal generation under control of the demodulated pilot signal. The video and sound programs presented by a conventional television receiver tuned to a private service channel comprises offensive interrupted bursts of two intermittently alternating programs which, moreover, may vary in intensity.
Inventors
No inventors recorded.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:19
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/167
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
205 words
In combination in a converter for receiving and operating upon an incident composite signal formed of at least one information signal, successive passages of which are distributed among and conveyed by plural transmission channels, and a pilot signal having modulated thereon switching information for identifying the transmission channel conveying said information signal, said converter including an output port, Means for selecting and demodulating said pilot signal and for generating a switching control signal corresponding to said switching information, means for selectively receiving said plural transmission channels, means responsive to said switching control signal for operatively selecting the changing, particular transmission channel of the channel array signal then conveying said information signal for receiving by said receiving means and connections thereby to said output port, wherein said converter further comprises variable gain amplifier means connected to said selecting means, means for monitoring the amplitude of the output of said variable gain means, means for varying the gain of said variable gain means in accordance with the output of said monitoring means, wherein said amplitude monitoring means includes sample and hold means including plural storage elements, and means for operatively selecting a changing one of said storage elements for operative service responsive to said switching control signal.
Claim 2
Dependent Claim
205 words
In combination in a converter for receiving and operating upon an incident composite signal formed of at least one information signal, successive passages of which are distributed among and conveyed by plural transmission channels, and a pilot signal having modulated thereon switching information for identifying the transmission channel conveying said information signal, said converter including an output port, Means for selecting and demodulating said pilot signal and for generating a switching control signal corresponding to said switching information, means for selectively receiving said plural transmission channels, means responsive to said switching control signal for operatively selecting the changing, particular transmission channel of the channel array signal then conveying said information signal for receiving by said receiving means and connections thereby to said output port, wherein said converter further comprises variable gain amplifier means connected to said selecting means, means for monitoring the amplitude of the output of said variable gain means, means for varying the gain of said variable gain means in accordance with the output of said monitoring means, wherein said amplitude monitoring means includes sample and hold means including plural storage elements, and means for operatively selecting a changing one of said storage elements for operative service responsive to said switching control signal.
Claim 3
Dependent Claim
191 words
In combination in a signal converter for operating on an ensemble of television signals comprising at least one unencripted video signal, at least one encripted video signal having consecutive segments thereof present on differing transmission channels, and a pilot carrier having modulated thereon switching information sufficient to identify the transmission channel conveying each encripted signal, said converter comprising pilot demodulator means for generating switching control signals in accordance with said pilot modulation, a mixer, plural controlled gates, plural local oscillators, means for enabling a selected changing one of said controlled gates responsive to said switching control signals for connecting a changing one of said local oscillators to said mixer, means for connecting the signal ensemble to said mixer, further comprising automatic gain control means including a variable gain amplifier connected to said mixer, means for sampling a measure of the output of said amplifier, and means for varying the gain of said variable gain amplifier responsive to said signal sampling means, said gain varying means including plural gain control signal storage elements, and means responsive to said switching control signal for operatively selecting a changing one of said plural storage elements.
Claim 4
Dependent Claim
191 words
In combination in a signal converter for operating on an ensemble of television signals comprising at least one unencripted video signal, at least one encripted video signal having consecutive segments thereof present on differing transmission channels, and a pilot carrier having modulated thereon switching information sufficient to identify the transmission channel conveying each encripted signal, said converter comprising pilot demodulator means for generating switching control signals in accordance with said pilot modulation, a mixer, plural controlled gates, plural local oscillators, means for enabling a selected changing one of said controlled gates responsive to said switching control signals for connecting a changing one of said local oscillators to said mixer, means for connecting the signal ensemble to said mixer, further comprising automatic gain control means including a variable gain amplifier connected to said mixer, means for sampling a measure of the output of said amplifier, and means for varying the gain of said variable gain amplifier responsive to said signal sampling means, said gain varying means including plural gain control signal storage elements, and means responsive to said switching control signal for operatively selecting a changing one of said plural storage elements.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-14 | 1976-11-13 | 1977-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-14 | 1980-11-13 | 1981-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-14 | 1984-11-13 | 1985-05-15 | $7700.00 | Window Closed / Lapsed |