US3729576A
Expired / Lapsed
US
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Encoding and decoding system for catv
Assignee: Optical Systems Corp
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Filing: 1971-02-08
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Granted: 1973-04-24
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Expires: 1991-02-08
Abstract
Abstract A video signal encoding system is provided by amplitude modulating a video carrier modulated with video, with a sinusoidal waveform whereby the amlitude levels of the sync portion of the video waveform as well as the video portion of the video waveform are altered. Decoding may be achieved by remodulating the encoded video waveform with a decoding sine wave in antiphase with the encoding sine wave and thereafter modulating the result, to eliminate residual error, with a cosine function wave applied in phase opposition to the error component of the resultant, which has twice the frequency of the basic encoding sine wave, but preferably the sequence of the decoding remodulations is reversed.
Inventors
- 👤 P Court
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:27
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/167; H04N7/171; H04N7/1713
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
181 words
A system for encoding and decoding video signals modulated on a carrier comprising: a transmitter having a source of first sinewave signals having a predetermined frequency and phase relationship relative to the freequency and occurrence of the horizontal synchronizing signal portions of said video signals, first means for modulating said video signals modulated on a carrier with said first sinewave signals, a source of second sinewave signals having a predetermined frequency and phase relationship relative to the frequency and phase of said first sinewave, second means for modulating the output of said first means for modulating with said second sinewave, and means for transmitting the output of said second means for modulating, a receiver for receiving said output from said second means for modulating from said transmitter, said receiver having a source of third sinewave signals having the frequency of said first sinewave signals and being in antiphase therewith, and third means for modulating said output from said second means for modulating with said third sinewave signals to substantially restore said video signals modulated on a carrier to their original state.
Claim 2
Independent Claim
181 words
A system for encoding and decoding video signals modulated on a carrier comprising: a transmitter having a source of first sinewave signals having a predetermined frequency and phase relationship relative to the freequency and occurrence of the horizontal synchronizing signal portions of said video signals, first means for modulating said video signals modulated on a carrier with said first sinewave signals, a source of second sinewave signals having a predetermined frequency and phase relationship relative to the frequency and phase of said first sinewave, second means for modulating the output of said first means for modulating with said second sinewave, and means for transmitting the output of said second means for modulating, a receiver for receiving said output from said second means for modulating from said transmitter, said receiver having a source of third sinewave signals having the frequency of said first sinewave signals and being in antiphase therewith, and third means for modulating said output from said second means for modulating with said third sinewave signals to substantially restore said video signals modulated on a carrier to their original state.
Claim 3
Dependent Claim
56 words
A system as recited in claim 1 wherein the frequency of said first sinewave signals is the same as the frequency of the horizontal synchronizing signals, and the phase of said first sinewave signals is established to reduce the amplitude of said horizontal synchronizing signals by the relatively negative going portions of said first sinewave signals.
Claim 4
Dependent Claim
24 words
A system as recited in claim 1 wherein the frequency of said second sinewave signals is twice the frequency of said first sinewave signals.
Claim 5
Dependent Claim
54 words
A system as recited in claim 1 wherein the frequency of said first sinewave signals is twice the frequency of the horizontal synchronizing signals, and the phase of said first sinewave signals is established to reduce the amplitude of said horizontal synchronizing signals by the relatively negative going portions of said first sinewave signals.
Claim 6
Dependent Claim
113 words
A system as recited in claim 4 wherein at said transmitter there is included a source of a fourth sinewave for having the frequency of said horizontal synchronizing signals and a phase which is periodically switched to be plus or minus 90* out of phase therefrom, and a fourth means at said transmitter for modulating the output of said second means for modulating, at said receiver there being means for generating fifth sinewave signals which are switched to be in antiphase with said fourth sinewave signals, and fifth means for modulating the output of said third means for modulating with said fifth sinewave signals to decode said video signals modulated on a carrier.
Claim 7
Dependent Claim
24 words
A system as recited in claim 4 wherein the frequency of said second sinewave signals is twice the frequency of said first sinewave signals.
Claim 8
Dependent Claim
74 words
A system as recited in claim 1 wherein said transmitter includes means for generating program audio signals smodulated on a carrier, and means for adding said program audio modulated on a carrier, said first and second means for modulating said video modulated on a carrier modulating said respective first and second sinewaves on said program audio signals modulated on a carrier simultaneously with their being modulated on said video signals modulated on a carrier.
Claim 9
Dependent Claim
37 words
A system as recited in claim 1 wherein the modulation index of said first sinewave signals is on the order of 0.3, and the modulation index of said second sinewave signals is on the order of 0.045.
Claim 10
Independent Claim
130 words
A system for encoding video signals moduLated on a carrier comprising: a first source of first sinewave signals having a predetermined frequency relative to the frequency of the horizontal synchronizing and blanking signals of said video signals and having a phase established to reduce the amplitude of the horizontal synchronizing signals by the relatively negative going portions of said first sinewave signals, a second source of second sinewave signals having a predetermined frequency and phase relationship relative to the frequency and phase of said first sinewave, first means for modulating said video signals modulated on a carrier with said first sinewave signals, second means for modulating the output of said first means for modulating with said second sinewave, and means for transmitting the output of said second means for modulating.
Claim 11
Independent Claim
130 words
A system for encoding video signals moduLated on a carrier comprising: a first source of first sinewave signals having a predetermined frequency relative to the frequency of the horizontal synchronizing and blanking signals of said video signals and having a phase established to reduce the amplitude of the horizontal synchronizing signals by the relatively negative going portions of said first sinewave signals, a second source of second sinewave signals having a predetermined frequency and phase relationship relative to the frequency and phase of said first sinewave, first means for modulating said video signals modulated on a carrier with said first sinewave signals, second means for modulating the output of said first means for modulating with said second sinewave, and means for transmitting the output of said second means for modulating.
Claim 12
Dependent Claim
42 words
A system as recited in claim 1 wherein the frequency of said first sinewave signals is the same frequency as that of said horizontal synchronizing signals, the frequency of said second sinewave signals is twice the freqeuncy of said first sinewave signals.
Claim 13
Dependent Claim
104 words
A system as recited in claim 9 wherein the said horizontal of said first sinewave signals is twice the frequency of said horizontal synchronizing signals, the frequency of said second sinewave signals is twice the frequency of said first sinewave signals, and there is included a source of fourth sinewave signals having the frequency of said horizontal synchronizing signals and a phase which is periodically switched to be in plus or minus 90* out of phase with the time of occurrence of said horizontal synchronizing signals, and third means for modulating the output of said second means for modulating with said third sinewave signals.
Claim 14
Dependent Claim
46 words
A system as recited in claim 10 wherein the degree of modulation of said video signals modulated on a carrier by said first sinewave signals is 0.3, the degree of modulation of said video signals modulated on a carrier by said second sinewave signals is 0.045.
Claim 15
Dependent Claim
65 words
A system as recited in claim 11 wherein the degree of modulation of said video signals modulated on a carrier by said first sinewave signals is 0.3, the degree of modulation of said video signals modulated on a carrier by said second sinewave signals is 0.045, the degree of modulation of said video signals modulated on a carrier by said third sinewave signals is 0.1.
Claim 16
Dependent Claim
83 words
A system as recited in claim 9 wherein there is included means for generating program audio signals modulated on a carrier, and means for adding said program audio signals moudulated on a carrier to said video signals modulated on a carrier prior to being applied to said first and second means for modulating, for modulating said respective first and second sinewaves on said program audio signals modulated on a carrier simultaneously with their being modulated on said video signals modulated on a carrier.
Claim 17
Dependent Claim
89 words
In a system wherein video signals modulated on a carrier are encoded by being first modulated with first sinewave signals and thereafter with second sinewave signals having a predetermined phase and frequency relative to said first sinewave signals, a decoder comprising: means for deriving from said encoded signals third sinewave signals having the same frequency as said first sinewave signals but being in antiphase therewith, and means for modulating said encoded video signals modulated on a carrier with said third sinewave signals for eliminating the effects of the encoding.
Claim 18
Dependent Claim
89 words
In a system wherein video signals modulated on a carrier are encoded by being first modulated with first sinewave signals and thereafter with second sinewave signals having a predetermined phase and frequency relative to said first sinewave signals, a decoder comprising: means for deriving from said encoded signals third sinewave signals having the same frequency as said first sinewave signals but being in antiphase therewith, and means for modulating said encoded video signals modulated on a carrier with said third sinewave signals for eliminating the effects of the encoding.
Claim 19
Dependent Claim
151 words
In a system wherein video signals modulated on a carrier are encoded by being first modulated with first sinewave signals and thereafter with second sinewave signals having a predetermined phase and frequency relative to said first sinewave signals and thereafter being modulated with third sinewave signals having the frequency of the horizontal synchronizing signals and a phase which varies plus or minus 90* relative to the phase thereof, a Decoder comprising: means for deriving fourth sinewave signals from said encoded signals having the same frequency but being in antiphase with said first sinewave signals, fourth means for modulating said encoded signals with said fourth sinewave signals, means for deriving fifth sinewave signals having the same frequency but being in antiphase with said third sinewave signals, and means for modulating the output of said fourth means for modulating with said fifth sinewave signals to decode said video signals modulated on a carrier.
Claim 20
Dependent Claim
151 words
In a system wherein video signals modulated on a carrier are encoded by being first modulated with first sinewave signals and thereafter with second sinewave signals having a predetermined phase and frequency relative to said first sinewave signals and thereafter being modulated with third sinewave signals having the frequency of the horizontal synchronizing signals and a phase which varies plus or minus 90* relative to the phase thereof, a Decoder comprising: means for deriving fourth sinewave signals from said encoded signals having the same frequency but being in antiphase with said first sinewave signals, fourth means for modulating said encoded signals with said fourth sinewave signals, means for deriving fifth sinewave signals having the same frequency but being in antiphase with said third sinewave signals, and means for modulating the output of said fourth means for modulating with said fifth sinewave signals to decode said video signals modulated on a carrier.
References Cited (Backward Citations)
US3081376A
Cited
US3184537A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-23 | 1976-10-23 | 1977-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-23 | 1980-10-23 | 1981-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-23 | 1984-10-23 | 1985-04-24 | $7700.00 | Window Closed / Lapsed |