METHOD FOR DETERMINING RMS VALUE OF HARMONIC COMPONENTS IN SIGNAL Russian patent published in 1997 - IPC

FIELD: measurement technology. SUBSTANCE: method for spectral analysis of signal depends on conversion of input signal whereupon definite time intervals are discriminated according to this signal; RMS value of input signal and input-signal first harmonic frequency are found, sine-wave reference signal of first-harmonic frequency is shaped, first time interval within which signal does not reverse its polarity is selected, center of first time interval is determined, second time interval within which sine-wave reference signal does not reverse its polarity is selected, center of second time interval is determined, instant values of input signal are measured at time moment t₁ and that of reference signal, at time moment t₂; selected time moments t₁ and t₂ should be equally spaced from centers of time intervals; module of ratio of instant values of input and reference signals is determined; modules of ratios of instant values of input and reference signals are repeatedly measured for each pair of time intervals equally spaced from center of respective first and second time intervals; averaged value of modules of ratios of instant values of input and reference signals are found and RMS value of harmonic components of input signal is determined as square root of square difference of two values: RMS value of input signal and product of RMS value of sine-wave reference signal by averaged value of modules of ratio of instant values of input and reference signals. EFFECT: improved speed and measurement accuracy.