FIELD: instrument making.
SUBSTANCE: present invention pertains to information processing systems and measuring techniques and can be used in determining spectral content of a periodic multiple frequency signal, containing interharmonics and given by digital read-outs. For an initial signal a(ti), given by readings of instantaneous values for a series of frequencies ω1, ω2,…, ωk,…, ωn, the instantaneous spectral density is determined. Amplitude Amk and phase φ'k of detected frequency components of the signal ωk, are successively determined. From the obtained values of Amk, ωk, φk , the spectral content of the initial signal a(ti), can be determined. Values of instantaneous spectral density S(ωk) are determined using the first programming unit. Using the third programming unit, values of auxiliary instantaneous spectral density S0(ωk) can be determined at the same time as the values of instantaneous spectral density S(ωk). The given values for the next frequency are determined. The process is repeated until equation of frequencies ωk and ωn. Using the second programming unit, the difference Sp(ωk) between values of instantaneous S(ωk) and auxiliary instantaneous S0(ωk) spectral densities is determined. Using the expression: 
, where Amy is the preset value of amplitude, from frequency values ωk, corresponding to extreme values of difference in characteristic of distribution of instantaneous spectral density Sp(ωk) of the initial signal, extreme values of Sp(ωk), are detected. The amplitude Amk of detected frequency components of the initial signal (ωk) is then determined using the first calculator. The phases φk of detected frequency components of the signal (ωk) are determined using the second calculator. When determining phases of frequency components the following conditions are used: for S1(ωk)>0 and S2(ωk)>0, φk(ωk)=φ'k(ωk); for S1(ωk)<0 and S2(ωk)>0, φk(ωk)=φ'k(ωk)+180; for S1(ωk)<0 and S2(ωk)<0, φk(ωk)=φ'k(ωk)-180; for S1(ωk)>0 and S2(ωk)<0, φk(ωk)=φ'k(ωk); using the fourth programming unit, values Amk and φk, corresponding to ωk, are stored. The first and third programming units are set such that, the signal at the inputs of the programming units reach the outputs of the sensor of the analysed signal. The first and second calculators are set such that, the signal at the inputs of the calculators reaches the outputs of the second programming at the same time, and the signal from the output of the calculators and the second programming unit reaches the outputs of the fourth programming unit.
EFFECT: increased selectivity of detecting frequency components of a signal during analysis of the spectral content of a periodic multiple frequency signal, containing interharmonics and given by digital read-outs.
3 dwg, 2 tbl
