DIGITAL METHOD OF MEASURING PHASE OF HARMONIC SIGNAL Russian patent published in 2018 - IPC G01R19/25 G01R25/00 

FIELD: measurement technology; physics.

SUBSTANCE: digital method for measuring phase of harmonic signal makes it possible to simplify the realization of determination of phase of a harmonic signal and to improve the accuracy of the phase determination when the original signal is noisy. Method is based on receiving the primary signal x(t) followed by analog-to-digital conversion using two analog-to-digital converters (ADCs) at two different frequencies. As a result, we get two number arrays y1[i], i=1…K and y2[i], i=1…K-d, where K and K-d are the number of samples of the first and second ADCs, respectively, in measurement interval T, d>1. We select for further processing one of these arrays, which will represent the secondary signal obtained as a result of sampling the primary signal with a frequency below the Nyquist frequency. We calculate with a fast Fourier transform the approximate integer value of the number of periods kp0 of the secondary signal. Create M*N reference signals in range of the number of periods kp2(p)=kp0-1+p*2/N, N – number of steps to search for the number of periods of the secondary signal and phase ϕ2(j)=-π/2+j*27π/M, M is the number of steps to search for the phase value of the secondary signal. We calculate the sums of squared deviations of the secondary source and reference signals for each value of p: ssd(j), j=1…M. We find the minimum values ssd(j); j=1:M, and the value of jmin corresponding to the condition ssd(jmin)=min(ssd(j)), j=1:M each value of p, calculate the current values of the phase function ϕ_result(p)=-π/2+jmin*2π/M, p=1…N. Find the values min(ϕ_result(p)), p=1:N, and the value of pmin corresponding to the condition ϕ_result (pmin)=min(ϕ_result(p)), p=1:M, calculate the total phase value ϕ_res=ϕ_result(pmin), calculate the resulting phase value ϕ_out=ϕ_res or ϕ_out=π-ϕ_res, if abs(ϕ_res)>π/2.

EFFECT: technical result in the realization of claimed method is simplification of the method implementation and an increase in the accuracy of the phase detection with noisy initial signal.

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