US 4,070,634 AGranted

Phase comparison systems employing improved phaselock loop apparatus

AssigneeNavidyne Corporation

InventorsA. Clifford Barker, Edmund S. Zavada

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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.

Claims17

Dependent claims

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.

2 more elements

Dependencies are inferred from the claim text.