Phase comparison systems employing improved phaselock loop apparatus
First Claim
1. A phase comparison system comprising a pair of phase lock loops responsive to first and second input signals, respectively, and means for comparing corresponding output signals of said phase lock loops, each phase lock loop comprising:
- means for producing an error signal representative of the phase difference between an input signal and a reference signal;
means responsive to said error signal for generating a signal having a frequency which varies in accordance with said phase difference;
means for generating a pulse train signal having a pulse repetition frequency which is orders of magnitude higher than the frequency of said variable-frequency signal; and
means for deriving said reference signal from said variable-frequency signal and said pulse train signal, said deriving means including a pulse deletion circuit which deletes pulses from said pulse train signal in response to said variable-frequency signal.
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Abstract
A high-accuracy phase comparison system for noise-contaminated fixed-frequency input signals, such as Omega radionavigation signals, employs a pair of phaselock loops in which output pulses from a high-frequency oscillator are deleted at the frequency of a variable-frequency oscillator which is responsive to the detected phase difference between the associated input signal and an associated reference signal, thereby to provide a high-frequency intermediate signal which is frequency-divided to produce the reference signal continuously and free of noise. The relative phase of the input signals may be determined by phase-comparing the reference signals of the two phaselock loops or, to provide even higher precision, by phase-comparing the variable-frequency signals of the two loops.
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Citations
17 Claims
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1. A phase comparison system comprising a pair of phase lock loops responsive to first and second input signals, respectively, and means for comparing corresponding output signals of said phase lock loops, each phase lock loop comprising:
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means for producing an error signal representative of the phase difference between an input signal and a reference signal; means responsive to said error signal for generating a signal having a frequency which varies in accordance with said phase difference; means for generating a pulse train signal having a pulse repetition frequency which is orders of magnitude higher than the frequency of said variable-frequency signal; and means for deriving said reference signal from said variable-frequency signal and said pulse train signal, said deriving means including a pulse deletion circuit which deletes pulses from said pulse train signal in response to said variable-frequency signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification