US3699256A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for accurately detecting the time of occurrence of a waveform
Assignee: Tektronix Inc
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Filing: 1970-12-28
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Granted: 1972-10-17
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Expires: 1990-12-28
Abstract
Abstract A circuit for accurately determining the time of occurrence of television synchronization pulses includes a means for establishing sync waveform tips at a first voltage value and means for controlling the amplitude of the video waveform so the blanking level achieves a second voltage value. The time of the synchronization pulse is then determined midway between these values. A pair of feedback loops are provided for substantially clamping the sync tips to the first value via a first low pass feedback circuit operating outside of the gain controlled system, and a high pass feedback circuit operating within a relatively fixed signal level environment.
Inventors
- 👤 Stephen A Roth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:41
CPC Classifications
G; G01; G01R; G01R13/00; G01R13/20; G01R13/22; G01R13/32; H; H04; H04N; H04N5/00; H04N5/04; H04N5/08
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
108 words
A circuit for accurately detecting the time of occurrence of a waveform comprising: first means for detecting a first amplitude level of said waveform, second means for detecting a second amplitude level of said waveform, amplifying means for receiving said waveform and for varying the amplitude of said waveform under the control of the first means For detecting a first level of said waveform, for changing the first level of said waveform until such level as detected corresponds to a first predetermined value, and means for detecting a third level of said waveform between the first and second levels to establish the time of occurrence of said waveform.
Claim 2
Dependent Claim
108 words
A circuit for accurately detecting the time of occurrence of a waveform comprising: first means for detecting a first amplitude level of said waveform, second means for detecting a second amplitude level of said waveform, amplifying means for receiving said waveform and for varying the amplitude of said waveform under the control of the first means For detecting a first level of said waveform, for changing the first level of said waveform until such level as detected corresponds to a first predetermined value, and means for detecting a third level of said waveform between the first and second levels to establish the time of occurrence of said waveform.
Claim 3
Dependent Claim
60 words
The circuit according to claim 1 further including means, under the control of the second means for detecting a second level of said waveform, for adding a value to said waveform until the second level thereof corresponds to a second predetermined value, said third level detecting means detecting a third level of said waveform between said first and second values.
Claim 4
Dependent Claim
119 words
A circuit for detecting synchronization pulses of a television video signal waveform comprising: means for detecting the tips of synchronization pulses in said video waveform and means responsive thereto for adding a value to the video waveform for causing said tips of said synchronization pulses to assume a first predetermined level, second means for detecting the blanking level of said video waveform, amplifier means for said video waveform responsive to said means for detecting the blanking level for changing the amplitude of said video waveform until the blanking level corresponds to a second predetermined level, and means responsive to an intermediate level of said video waveform between said first and second predetermined levels for providing a synchronization pulse output.
Claim 5
Dependent Claim
119 words
A circuit for detecting synchronization pulses of a television video signal waveform comprising: means for detecting the tips of synchronization pulses in said video waveform and means responsive thereto for adding a value to the video waveform for causing said tips of said synchronization pulses to assume a first predetermined level, second means for detecting the blanking level of said video waveform, amplifier means for said video waveform responsive to said means for detecting the blanking level for changing the amplitude of said video waveform until the blanking level corresponds to a second predetermined level, and means responsive to an intermediate level of said video waveform between said first and second predetermined levels for providing a synchronization pulse output.
Claim 6
Dependent Claim
61 words
The apparatus according to claim 3 wherein said means for causing said synchronization tips to assume a first predetermined level includes a first feedback loop including low pass filter means for adding a value to said video waveform, and a second feedback loop, including high pass filter means, inside said first feedback loop for adding a value to said video waveform.
Claim 7
Dependent Claim
69 words
The circuit according to claim 3 wherein said means for causing said synchronization tips to assume a first predetermined level comprises a first feedback circuit including low pass filter means for adding a value to said video waveform before amplification thereof by said amplifier means, and second feedback means including high pass filter means for adding a value to said video waveform after amplification thereof by said amplifier means.
Claim 8
Dependent Claim
30 words
The circuit according to claim 5 wherein said second feedback means is responsive to high frequency waveform tilt components while being rate-limited for rendering it relatively unresponsive to noise components.
Claim 9
Dependent Claim
44 words
The circuit according to claim 3 wherein said means for detecting the tips of synchronization pulses in said video waveform includes means responsive to the variations in said waveform substantially for the duration of synchronization pulses, and means for remembering the last value reached.
Claim 10
Dependent Claim
65 words
The circuit according to claim 7 wherein said means responsive to the variations in said waveform substantially during the duration of synchronization pulses comprises a comparator operative during said synchronization pulses as the same reach a predetermined value and wherein said means for remembering comprises capacitor means for receiving current in response to operation of said comparator when said synchronization pulses reach said predetermined value.
Claim 11
Dependent Claim
119 words
The circuit according to claim 3 wherein said second means for detecting the blanking level comprises: first means responsive to the duty cycle of the television video waveform including means for receiving said video waveform as an input and including means for providing a predetermined output for a given duration of input corresponding to the blanking level of the video waveform, a feedback circuit, responsive to said duty cycle responsive means, for affecting the level of the video waveform relative to the duty cycle responsive means, and a gating circuit between said feedback circuit and said duty cycle responsive means for coupling the video waveform to the duty cycle responsive means as the video waveform reaches a predetermined value.
Claim 12
Dependent Claim
28 words
The circuit according to claim 9 including means responsive to said video waveform failing to reach an intermediate level for decoupling a discharge path from said capacitor means.
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) | 1975-10-17 | 1976-04-17 | 1976-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-17 | 1980-04-17 | 1980-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-17 | 1984-04-17 | 1984-10-17 | $7700.00 | Window Closed / Lapsed |