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Automatic oscillator frequency control systemA frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder.
Document ID
19860011197
Acquisition Source
Legacy CDMS
Document Type
Other - Patent
Authors
Smith, S. F.
(Smith (Stephen F.), Knoxville Tenn., United States)
Date Acquired
August 12, 2013
Publication Date
October 29, 1985
Subject Category
Electronics And Electrical Engineering
Accession Number
86N20668
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
US-PATENT-4,550,292|NASA-CASE-GSC-12804-1
Patent Application
US-PATENT-APPL-SN-529803
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