Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1988-01-20
1989-10-03
Brigance, Gerald
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358149, 358150, 315364, 340814, H04N 504
Patent
active
048720550
ABSTRACT:
A line sychronizing circuit in a picture display device, has a phase control loop including an oscillator and a phase comparison stage. In order to enlarge the capture range of the control loop, the phase comparison stage is in the form of a phase-frequency detector having a trigger action on edges of pulses applied, the circuit being provided with means for inhibiting the supply of the control signal form the phase-frequency detector during a predetermined period after establishing that the phase difference measured by the phase-frequency detector between the local line-frequency signal and the incoming line synchronizing signal is larger than a predetermined value. In the perdetermined period, the oscillator signal has substantially the same frequency as before establishing that the phase difference measured by the phase frequency detector is larger than the predetermined value. The supply of the control signal is restored during a second predetermined period after the supply of the control signal has been inhibited, and this irrespective of the phase difference between the local line signal and the incoming line synchronizing signal.
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Hulshof Jozef J. M.
Teuling Dirk J.
Brigance Gerald
Goodman Edward W.
Hjerpe Richard
U. S. Philips Corporation
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