Disciplined oscillator system with frequency control and accumulated time control
First Claim
1. A disciplined oscillator system which comprises means for providing constant frequency signals including pulses which are repetitive at fixed intervals of time, standard frequency oscillator means for providing a standard frequency output and having an input for controlling the frequency thereof, frequency controller means responsive to said constant frequency signals for detecting variances in the frequency of said standard frequency output and providing a frequency control signal, time controller means responsive to said pulses for detecting time displacements of said standard frequency output with respect to said pulses for providing a timing control signal, and means responsive to said frequency control signal and to said timing control signal for applying a correction signal to said input.
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Abstract
A disciplined oscillator system having a standard oscillator which is automatically corrected for both frequency errors and time error accumulation to a constant frequency signal which is derived from the WWVB carrier frequency and the WWVB TIME CODE to maintain overall frequency accuracy within one part in 109 notwithstanding oscillator aging and in spite of jitter and distortion due to propagation delays and noise which may cause loss of, or time jitter in, the WWVB signals. Frequency errors are detected through the use of a counter (24) having a measurement accuracy greater than one part in 1010. An error detector (26) derives correction signals by averaging a plurality of frequency variances obtained in successive measurement cycles. Timing errors are corrected by dividers (34, 40) controlled by a timing discriminator (36) which responds to timing variance between signals from the standard oscillator and from the WWVB reference which are phase locked to those TIME CODE signals which are substantially free of noise and jitter. The timing correction is inhibited after the standard oscillator is corrected. Frequency correction is applied continuously.
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Citations
39 Claims
- 1. A disciplined oscillator system which comprises means for providing constant frequency signals including pulses which are repetitive at fixed intervals of time, standard frequency oscillator means for providing a standard frequency output and having an input for controlling the frequency thereof, frequency controller means responsive to said constant frequency signals for detecting variances in the frequency of said standard frequency output and providing a frequency control signal, time controller means responsive to said pulses for detecting time displacements of said standard frequency output with respect to said pulses for providing a timing control signal, and means responsive to said frequency control signal and to said timing control signal for applying a correction signal to said input.
- 25. In a disciplined oscillator system utilizing a constant frequency reference signal and having standard frequency oscillator means for providing a standard frequency output which is variable in response to a frequency control signal, frequency controller means comprising a counter having a capacity to count to a number greater than the resolution in frequency to which said standard frequency output is to be controlled, means responsive to said constant frequency signal for repetitively enabling said counter to count each repetition of said standard frequency output for an interval changed upon each repetitive enablement sufficient to count a number of cycles of said standard frequency output at least equal to said frequency resolution, and means responsive to the counts stored in said counter for providing said frequency control signal.
- 32. In a disciplined oscillator system utilizing a source of pulses repetitive at fixed intervals of time and having standard oscillator means having a standard frequency output which is variable in frequency in response to a control signal, time controller means comprising means responsive to said standard frequency output and said fixed interval pulses for providing a train of reference pulses time-locked to said fixed interval pulses, and means responsive to the phase difference between said fixed interval pulses and said reference pulses for producing said control signal.
Specification