US3896265A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frame synchronization system
Assignee: Fujitsu Ltd
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Filing: 1973-10-26
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Granted: 1975-07-22
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Expires: 1993-10-26
Abstract
Abstract A frame synchronization system has false random signals produced by output clock signals of a voltage controlled oscillator and clock signals produced by shifting the output clock signals by pi /2 and input signals correlated by correlators. The voltage corresponding to the phase difference is applied to an input of the voltage controlled oscillator. Correlators correlate the output clock signals of the voltage controlled oscillator. A level detection circuit detects a specific level of positive polarity of the output of the correlators. The system pulls a frame into synchronization at a true stable point by feeding to an input of the voltage controlled oscillator the voltage corresponding to the phase difference obtained from the correlation between the clock signals shifted by pi /2 and the input signals when a specific level is detected in the level detection circuit.
Inventors
- 👤 Takao Hara
- 👤 Yukio Murayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:26
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/10; H03L7/101; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/204; H04B7/212; H04B7/2125; H04J; H04J3/00; H04J3/02; H04J3/06; H04J3/0602; H04J3/0605; H04J3/0611
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
344 words
A frame synchronization system for input signals comprising a combination of false random signals and clock signals, a first phase detector having an input supplied with the input signals, the first phase detector comprising A first correlator and a second correlator and having other inputs and an output, a voltage controlled oscillator having an input selectively coupled to the output of the first phase detector, the voltage controlled oscillator having an input, a first feedback circuit comprising a first feedback loop and a 90* phase shifter circuit connected therein for shifting output signals of the oscillator 90* in phase, the first feedback loop being connected between the output of the voltage controlled oscillator and another input of the first phase detector and a second feedback circuit comprising a second feedback loop and a false random signal generator connected therein for generating false random signals, the second feedback loop being connected between the output of the voltage controlled oscillator and still another input of the first phase detector, the frame synchronization system comprising a second phase detector including the first correlator and a third correlator and having an input coupled to the output of the voltage controlled oscillator for correlating the input signals with the output of the voltage controlled oscillator, the second phase detector having an output; a first level detection circuit having an input coupled to the output of the second phase detector for detecting a specific level of positive polarity of the output of the second phase detector, the first level detection circuit having an output; a source of constant voltage; and a switch circuit having an armature connected to the input of the voltage controlled oscillator, a first contact coupled to the output of the first phase detector and a second contact connected to the source of constant voltage, the switch circuit being coupled to the output of the first level detection circuit whereby the armature of the switch circuit selectively contacts the first and second contacts in accordance with specific levels of positive polarity detected by the level detection circuit.
Claim 2
Dependent Claim
344 words
A frame synchronization system for input signals comprising a combination of false random signals and clock signals, a first phase detector having an input supplied with the input signals, the first phase detector comprising A first correlator and a second correlator and having other inputs and an output, a voltage controlled oscillator having an input selectively coupled to the output of the first phase detector, the voltage controlled oscillator having an input, a first feedback circuit comprising a first feedback loop and a 90* phase shifter circuit connected therein for shifting output signals of the oscillator 90* in phase, the first feedback loop being connected between the output of the voltage controlled oscillator and another input of the first phase detector and a second feedback circuit comprising a second feedback loop and a false random signal generator connected therein for generating false random signals, the second feedback loop being connected between the output of the voltage controlled oscillator and still another input of the first phase detector, the frame synchronization system comprising a second phase detector including the first correlator and a third correlator and having an input coupled to the output of the voltage controlled oscillator for correlating the input signals with the output of the voltage controlled oscillator, the second phase detector having an output; a first level detection circuit having an input coupled to the output of the second phase detector for detecting a specific level of positive polarity of the output of the second phase detector, the first level detection circuit having an output; a source of constant voltage; and a switch circuit having an armature connected to the input of the voltage controlled oscillator, a first contact coupled to the output of the first phase detector and a second contact connected to the source of constant voltage, the switch circuit being coupled to the output of the first level detection circuit whereby the armature of the switch circuit selectively contacts the first and second contacts in accordance with specific levels of positive polarity detected by the level detection circuit.
Claim 3
Dependent Claim
118 words
A frame synchronization system as claimed in claim 1, wherein the first phase detector comprises the first correlator, said first correlator having an input connected to the false random signal generator via the second feedback loop for correlating the input signals and the output of the false random signal generator, the first correlator having an output, and the second correlator having an input connected to the output of the first correlator and another input connected to the 90* phase shifter circuit via the first feedback loop for correlating the output of the first correlator and the output of the 90* phase shifter circuit, the second correlator having an output coupled to the first contact of the switch circuit.
Claim 4
Dependent Claim
80 words
A frame synchronization system as claimed in claim 2, wherein the second phase detector comprises the first correlator and the third correlator, said third correlator having an input connected to the output of the first correlator and another input coupled to the output of the voltage controlled oscillator for correlating the output of the first correlator and the output of the voltage controlled oscillator, the third correlator having an output coupled to the input of the first level detection circuit.
Claim 5
Dependent Claim
145 words
A frame synchronization system as claimed in claim 3, further comprising a second level detection circuit having an input coupled to the output of the third correlator of the second phase detector for detecting a specific level of negative polarity of the output of the second phase detector, the second level detection circuit having an output, and circuit means having an input connected to the output of the voltage controlled oscillator and another input coupled to the output of the second level detection circuit when the specific level of negative polarity is detected by the second level detection circuit, the circuit means having an output connected to the input of the 90* phase shifter of the first feedback loop, the inpuT of the false random signal generator of the second feedback loop and the other input of the third correlator of the second phase detector.
Claim 6
Dependent Claim
65 words
A frame synchronization system as claimed in claim 4, further comprising a low pass filter connected between the output of the second correlator of the first phase detector and the first contact of the switch circuit and another low pass filter connected between the output of the third correlator of the second phase detector and the inputs of the first and second level detection circuits.
Claim 7
Dependent Claim
50 words
A frame synchronization system as claimed in claim 4, further comprising a flip flop connected between the output of the first level detection circuit and the switch circuit and another flip flop connected between the output of the second level detection circuit and said another input of the circuit means.
Claim 8
Dependent Claim
18 words
A frame synchronization system as claimed in claim 4, wherein the circuit means comprises a 180* phase shifter.
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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) | 1978-07-21 | 1979-01-20 | 1979-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-21 | 1983-01-20 | 1983-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-21 | 1987-01-20 | 1987-07-22 | $7700.00 | Window Closed / Lapsed |