US 4,066,952 AGranted

Phase measuring apparatus

AssigneeThe Solartron Electronic Group Limited

InventorAnthony John Ley

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Abstract

Apparatus for measuring the phase difference between two electrical signals Asin (wt+.theta.), Bsin (wt+.phi.), given a reference signal Vsin wt generated by the apparatus, comprises a phase lock loop for generating a clock frequency f = 360F where F is the frequency of the reference signal. This clock frequency f is then used to tune a 360 stage CCD transversal filter which is used to filter successively the two first-mentioned signals, whose phase difference is then measured by a zero intercept system. The clock frequency f is used to give phase difference in degrees. The phase lock loop comprises a 90-stage CCD to which the reference signal is applied. The output of the CCD is applied to one input of a phase sensitive detector whose other input is connected to receive the reference signal, and the control signal produced by the phase sensitive detector controls a voltage controlled oscillator whose output is applied to the clock input of the CCD.

Claims18

Dependent claims

Apparatus for measuring the phase difference between two electrical signals having the same frequency f, one of which is a reference signal and the other of which may be contaminated by harmonics, comprising:

circuit means responsive to the reference signal for generating clock pulses at a frequency which is a predetermined multiple of the frequency f of the reference signal;
a transversal filter for receiving and filtering the other signal to produce a filtered output signal, the filter comprising an N-stage charge-coupled device for receiving and sampling the other signal in combination with summing means arranged to generate the filtered output signal by receiving and summing respective weighted signals each derived from a respective stage of the charge-coupled device, the charge-coupled device being clocked in dependence upon the clock pulses at a rate equal to N times f and the weights of said weighted signals being selected in accordance with a predetermined function such that the transversal filter substantially reduces the harmonics in said other signal;
means responsive to the reference signal for generating a first timing signal at a predetermined point in each cycle thereof;
means responsive to said output signal of the transversal filter to produce a second timing signal at a point in each cycle thereof corresponding to said predetermined point;
and
means for determining the number of clock pulses between said first and second timing signals, said number being representative of the phase difference between the reference signal and the other signal.

3 more elements

Dependencies are inferred from the claim text.