US3845240A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sync pulse detector for video telephone system
Assignee: AG Communication Systems Corp
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Filing: 1972-10-16
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Granted: 1974-10-29
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Expires: 1992-10-16
Abstract
Abstract A video sync pulse detector for use in video telephone systems. Detection of sync pulses of proper frequency and duration is used to operate switching equipment to connect video telephone subscribers to a service operator. Sync pulse, separation, frequency and duration detection are all combined in the circuitry to accurately determine video signals.
Inventors
- 👤 J Alaily
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:56
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/14; H04N7/141; H04N7/147
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
192 words
A video signal sync pulse detector including: sync pulse separating means connected to a source of composite video signals operated in response to detection of pulses included in said video signals to generate sync pulses of a predetermined polarity and of a fixed amplitude at the same frequency and same width as said detected pulses; frequency detecting means connected to said pulse separating means, operated in response to said sync pulses generated by said separating means being within predetermined frequency limits to generate a first output signal; duty cycle detecting means connected to said pulse separating means, operated in response to said pulses generated by said separating means being within predetermined duration limits to generate a second output signal; first gating means connected to said frequency detecting means and to said duty cycle detecting means, operated in response to both said first and second output signals in combination, to generate a third output signal; an output means connected to said first gating means operated in response to said third output signal to provide an indication of the presence of sync pulses of correct frequency and correct duration in said composite video signals.
Claim 2
Dependent Claim
192 words
A video signal sync pulse detector including: sync pulse separating means connected to a source of composite video signals operated in response to detection of pulses included in said video signals to generate sync pulses of a predetermined polarity and of a fixed amplitude at the same frequency and same width as said detected pulses; frequency detecting means connected to said pulse separating means, operated in response to said sync pulses generated by said separating means being within predetermined frequency limits to generate a first output signal; duty cycle detecting means connected to said pulse separating means, operated in response to said pulses generated by said separating means being within predetermined duration limits to generate a second output signal; first gating means connected to said frequency detecting means and to said duty cycle detecting means, operated in response to both said first and second output signals in combination, to generate a third output signal; an output means connected to said first gating means operated in response to said third output signal to provide an indication of the presence of sync pulses of correct frequency and correct duration in said composite video signals.
Claim 3
Dependent Claim
47 words
A video signal sync pulse detector as claimed in claim 1 wherein said sync pulse separating means comprises a clamp circuit connected to said source of composite video signals and connected to said clamp circuit a comparator amplifier further including connection to a source of reference potential.
Claim 4
Dependent Claim
64 words
A video signal sync pulse detector as claimed in claim 1 wherein said frequency detecting means comprises: first and second monostable multivibrators each connected to said sync pulse separating means, second gating means; a first bistable multivibrator connected between said first monostable multivibrator and said second gating means and a second bistable multivibrator connected between said second monostable multivibrator and said second gating means.
Claim 5
Dependent Claim
46 words
A video signal sync pulse detector as claimed in claim 3 wherein said first and second monostable multivibrators each include a separate connection to an adjustable source of reference potential whereby upper and lower frequency limits of said pulses generated by said separating means are established.
Claim 6
Dependent Claim
101 words
A video signal sync pulse detector as claimed in claim 1 wherein said duty cycle detection means includes a first operational amplifier circuit; a clamp circuit connecting said sync separating means to said first operational amplifier; said first operational amplifier operated in response to output pulses from said sync pulse separating means; and comparator means including second and third operational amplifiers each connected to said first operational amplifier and each connected to a separate adjustable source of reference potential, said second and third operational amplifiers operated in response to operation of said first operational amplifier to generate said second output signal.
Claim 7
Dependent Claim
19 words
A video signal sync pulse detector as claimed in claim 1 wherein said gating means comprises a NAND gate.
Claim 8
Dependent Claim
42 words
A video signal sync pulse detector as claimed in claim 1 wherein said output means comprises a first inverting amplifier connected to said first gating means, a relay, and a second inverting amplifier connected between said first inverting amplifier and said relay.
Claim 9
Dependent Claim
32 words
A video signal sync pulse detector as claimed in claim 1 wherein there is further included: a differential amplifier connected between said source of video signals and said sync pulse separating means.
Claim 10
Dependent Claim
31 words
A video signal sync pulse detector as claimed in claim 1 wherein there is further included: an inverted amplifier connected between said sync pulse separating means and said frequency detecting means.
Claim 11
Dependent Claim
30 words
A video signal sync pulse detector as claimed in claim 1 wherein there is further included signal inverting means connected between said frequency detecting means and said first gating means.
Claim 12
Dependent Claim
31 words
A video signal sync pulse detector as claimed in claim 1 wherein there is further included: signal inverting means connected between said duty cycle detecting means and said first gating 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) | 1977-10-28 | 1978-04-29 | 1978-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-28 | 1982-04-29 | 1982-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-28 | 1986-04-29 | 1986-10-29 | $7700.00 | Window Closed / Lapsed |