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AssigneeZenith Electronics Corporation
InventorGopal K. Srivastava
Estimating the term…
An adaptive oscillator control system for use in television receivers or monitors includes a phase locked loop together with a static phase error correction system which responds to long term error signals of significant magnitude within the phase locked loop to adjust the free-running frequency of the oscillator. An oscillator range control includes a processor having a plurality of established oscillator frequency ranges which are identified by oscillator range code numbers. A measuring counter and clock circuit cooperate to count the number of clock signals occurring during the horizontal sync reference signal period to establish a frequency reference number. A first frequency approximation is provided based upon the oscillator range code number or a known standard scan frequency. A frequency detector examines the oscillator output and provides a second frequency approximation to adjust the oscillator frequency until it falls within the appropriate frequency range. A confidence circuit examines the consistency of oscillator frequency maintenance within the appropriate frequency range and upon establishing the desired confidence level enables the phase locked loop to provide synchronization. Thereafter, a lock detector responds to the occurrence of frequency and phase lock by the phase lock loop to enable the static phase error corrector and deactivate the oscillator range control system. The lock detector upon detecting horizontal synchronization, for broadcast type video, increases the second frequency approximation range.
For use within a system receiving an information signal and a periodic reference signal, an oscillator control for controlling the frequency and phase of an oscillator in accordance with a periodic reference signal having a frequency within a spectrum of reference frequencies, said oscillator control comprising:
For use within a system receiving an information signal and a periodic reference signal, a method for controlling the frequency and phase of an oscillator in accordance with the periodic reference signal having a frequency within a spectrum of reference frequencies comprising the steps of:
For use within a system receiving a video signal and a periodic sync signal, a horizontal scan oscillator control for controlling the frequency and phase of a horizontal scan oscillator in accordance with a periodic sync signal having a frequency within a spectrum of reference frequencies, said oscillator control comprising:
A method for controlling a horizontal oscillator forming part of a phase locked loop in response to a received horizontal sync signal, said method comprising:
Dependencies are inferred from the claim text.