US3961135A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Synchronized demodulation system
Assignee: NEC Corp
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Filing: 1973-12-27
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Granted: 1976-06-01
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Expires: 1993-12-27
Abstract
Abstract A demodulation system for use in a vestigial sideband system of an over-modulation type including a sampler for sampling a reduced carrier frequency component from a received modulated wave to be used for demodulation. A discriminator is operative to detect a vertical synchronizing signal portion in a vertical blanking period and thereupon to actuate the sampler, causing a carrier burst signal to build up. The carrier burst signal is subjected to filtering to derive a carrier wave which is supplied to a demodulator. A synchronizing pulse separator is connected to the demodulator to separate horizontal synchronizing pulses from a demodulated output, which pulses are fed back to the sampler to actuate it during the absence of the vertical synchronizing signal.
Inventors
- 👤 Miyoji Ohyama
- 👤 Yushi Uchida
- 👤 Tateo Onodera
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:09
CPC Classifications
H; H03; H03D; H03D1/00; H03D1/22; H04; H04N; H04N5/00; H04N5/44; H04N5/455
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
242 words
In a synchronized demodulation system including means for receiving a modulated carrier wave modulated by a composite signal containing first and second synchronizing signals having different time periods, said second synchronizing signal containing substantially no frequency components of said first synchronizing signal, the excess carrier ratio of said modulated carrier wave being smaller than unity but not smaller than 0.5, means for demodulating said modulated carrier wave by means of an internal carrier wave synchronized with the carrier rrequency component of said modulated carrier wave, thereby to regenerate said composite signal, means for separating said first synchronizing signal from said regenerated composite signal, means for generating sampling pulses upon reception of said separated first synchronizing signal, means for sampling said modulated carrier wave by said sampling pulses to derive a carrier burst signal, and means for selecting the carrier frequency component from said carrier burst signal to deliver said internal carrier wave for demodulation in said demodulating means, the improvement comprising: means responsive to said modulated carrier wave for generating a gate pulse in the time period of said second synchronizing signal; means responsive to said gate pulse for generating self-running synchronizing pulses with a repetition rate substantially equal to that of said first synchronizing signal during the time period of said gate pulse; and means responsive to said self-running synchronzing signal for generating addition sampling pulses to be applied to said sampling means during the time period of said gate pulse.
Claim 2
Dependent Claim
242 words
In a synchronized demodulation system including means for receiving a modulated carrier wave modulated by a composite signal containing first and second synchronizing signals having different time periods, said second synchronizing signal containing substantially no frequency components of said first synchronizing signal, the excess carrier ratio of said modulated carrier wave being smaller than unity but not smaller than 0.5, means for demodulating said modulated carrier wave by means of an internal carrier wave synchronized with the carrier rrequency component of said modulated carrier wave, thereby to regenerate said composite signal, means for separating said first synchronizing signal from said regenerated composite signal, means for generating sampling pulses upon reception of said separated first synchronizing signal, means for sampling said modulated carrier wave by said sampling pulses to derive a carrier burst signal, and means for selecting the carrier frequency component from said carrier burst signal to deliver said internal carrier wave for demodulation in said demodulating means, the improvement comprising: means responsive to said modulated carrier wave for generating a gate pulse in the time period of said second synchronizing signal; means responsive to said gate pulse for generating self-running synchronizing pulses with a repetition rate substantially equal to that of said first synchronizing signal during the time period of said gate pulse; and means responsive to said self-running synchronzing signal for generating addition sampling pulses to be applied to said sampling means during the time period of said gate pulse.
Claim 3
Dependent Claim
61 words
The demodulation system as set forth in claim 1, in which said additional sampling pulse generating means includes: an OR circuit having two inputs connected to the outputs of said first synchronizing signal separating means and of said self-running synchronizing pulse generating means; and a pulse generator responsive to the output of said OR circuit for generating said additional sampling pulses.
Claim 4
Dependent Claim
26 words
The demodulation system as set forth in claim 1, in which said carrier frequency component selecting means includes a band-pass filter for filtering the sampled output.
Claim 5
Dependent Claim
57 words
The demodulation system as set forth in clailm 1, in which said gate pulse generating means includes: suppressor means for suppressing the frequency components of said received modulated wave in the vicinity of said carrier frequency; a slicer connected to the output of said suppressor means; and a mono-stable multivibrator responsive to the output of said slicer.
Claim 6
Dependent Claim
57 words
The demodulation system as set forth in clailm 1, in which said gate pulse generating means includes: suppressor means for suppressing the frequency components of said received modulated wave in the vicinity of said carrier frequency; a slicer connected to the output of said suppressor means; and a mono-stable multivibrator responsive to the output of said slicer.
Claim 7
Dependent Claim
29 words
The demodulation system as set forth in claim 4, in which said self-running synchronizing pulses generating means includes: an astable multivibrator responsive to the output of said mono-stable multivibrator.
Claim 8
Dependent Claim
34 words
The demodulation system as set forth in claim 4, in which said mono-stable multivibrator has an output pulse, the width of which is somewhat longer than the time interval between said first synchronizing signals.
Claim 9
Dependent Claim
154 words
A demodulation system for use in a transmission system of the character in which a carrier wave is subjected to over-modulation with a composite signal containing first and second synchronizing signals, said demodulation system comprising: discriminator means for discriminating a first synchronizing signal portion from a second synchronizing signal portion in a received modulated wave; sampler means for sampling said received modulated wave during the presence of said first synchronizing signal portion in order to derive said carrier wave; demodulator means for demodulating said received modulated signal with said carrier wave; and separator means for separating said second synchronizing signal from said received modulated wave, said separated second synchronizing signal being fed back to said sampler means to actuate it during the absence of said first synchronizing signal, said separator means including a peak clamper responsive to the output of said demodulator means and a slicer responsive to the output of said peak clamper.
Claim 10
Dependent Claim
154 words
A demodulation system for use in a transmission system of the character in which a carrier wave is subjected to over-modulation with a composite signal containing first and second synchronizing signals, said demodulation system comprising: discriminator means for discriminating a first synchronizing signal portion from a second synchronizing signal portion in a received modulated wave; sampler means for sampling said received modulated wave during the presence of said first synchronizing signal portion in order to derive said carrier wave; demodulator means for demodulating said received modulated signal with said carrier wave; and separator means for separating said second synchronizing signal from said received modulated wave, said separated second synchronizing signal being fed back to said sampler means to actuate it during the absence of said first synchronizing signal, said separator means including a peak clamper responsive to the output of said demodulator means and a slicer responsive to the output of said peak clamper.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-06-01 | 1979-12-01 | 1980-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-01 | 1983-12-01 | 1984-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-01 | 1987-12-01 | 1988-06-01 | $7700.00 | Window Closed / Lapsed |