US3898379A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Means for reducing effect of low frequency component of video signal
Assignee: Allard Way Holdings Ltd
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Filing: 1974-01-09
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Granted: 1975-08-05
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Expires: 1994-01-09
Abstract
Abstract A television system is provided with circuitry which improves the quality of the video signals obtained under viewing conditions which usually have resulted in poor quality pictures being obtained. The circuitry removes any very low frequency component which is superimposed on the video signal without significantly reducing the useful information content of the video signals. The undesirable low frequency component arises particularly when a hazy scene is viewed or even when the camera is subjected to shock or vibration.
Inventors
- 👤 Michael Bernard Howe
- 👤 Charles Raymond Wil Richardson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:45
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/21
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
50 words
A television system including means for processing the picture content of the video signal to reduce the effects of relatively low frequency modulation signals having a frequency substantially less than the television line frequency which modulation signals are present due to haze or relatively bright areas in the viewed scene.
Claim 2
Dependent Claim
50 words
A television system including means for processing the picture content of the video signal to reduce the effects of relatively low frequency modulation signals having a frequency substantially less than the television line frequency which modulation signals are present due to haze or relatively bright areas in the viewed scene.
Claim 3
Dependent Claim
48 words
A television system as claimed in claim 1 and including means for extracting from received video signals said superimposed low frequency modulation signals, and means for subsequently recombining the extracted signals with the said received video signals so as to cancel therefrom the said low frequency modulation signals.
Claim 4
Dependent Claim
29 words
A system as claimed in claim 2 wherein said means for extracting from the received video signals the low frequency modulation signals superimposed thereon comprises a low pass filter.
Claim 5
Dependent Claim
39 words
A system as claimed in claim 2 wherein the extracted low frequency modulation signals are inverted prior to recombination with the said video signals, whereby a simple additive recombination results in algebraic cancellation of the low frequency modulation signals.
Claim 6
Dependent Claim
24 words
A system as claimed in claim 2, wherein means are provided for clamping the level of the recombined signal to any desired d.c. level.
Claim 7
Dependent Claim
21 words
A system as claimed in claim 2, wherein blanking signals are reinserted into said extracted signals prior to the recombination step.
Claim 8
Dependent Claim
142 words
In a television system including a video signal input which may contain successive line data signals which, within a field period, define a low frequency signal envelope whIch includes components having frequencies generally not in excess of one order of magnitude greater than the field frequency of the television system, the combination of: low pass filter means connected to said video signal input for producing an output approximating said low frequency signal envelope; combining means for combining said video signal input with said output of the low pass filter means to produce a composite signal in which said successive line data signals are present substantially in the absence of interference by said low frequency components beyond a selected d.c. level; means for recovering only that portion of said composite signal beyond said selected d.c. level; and means for amplifying the recovered signal.
Claim 9
Dependent Claim
142 words
In a television system including a video signal input which may contain successive line data signals which, within a field period, define a low frequency signal envelope whIch includes components having frequencies generally not in excess of one order of magnitude greater than the field frequency of the television system, the combination of: low pass filter means connected to said video signal input for producing an output approximating said low frequency signal envelope; combining means for combining said video signal input with said output of the low pass filter means to produce a composite signal in which said successive line data signals are present substantially in the absence of interference by said low frequency components beyond a selected d.c. level; means for recovering only that portion of said composite signal beyond said selected d.c. level; and means for amplifying the recovered signal.
Claim 10
Dependent Claim
16 words
In a television system as defined in claim 7 wherein said combining means includes an inverter.
Claim 11
Dependent Claim
27 words
In a television system as defined in claim 7 wherein said means for recovering comprises a clamp circuit clamping said composite signal to said selected d.c. level.
Claim 12
Dependent Claim
33 words
In a television system as defined in claim 7 wherein said combining means includes on insertion circuit for inserting gaps in said envelope caused by blanking periods between said successive line data signals.
Claim 13
Dependent Claim
27 words
In a television system as defined in claim 10 wherein said means for recovering comprises a clamp circuit clamping said composite signal to said selected d.c. level.
Claim 14
Dependent Claim
16 words
In a television system as defined in claim 11 wherein said combining means includes an inverter.
References Cited (Backward Citations)
US3780215A
Cited
US3643011A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |