SU1629869A1 - Harmonic analyzer - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the amplitude values of the harmonic components of periodic signals. The aim of the invention is to expand the frequency range of the first harmonic. This is achieved by a special spectrum conversion, at which the measured harmonic at the inputs of the low-pass filters does not depend on the change in the fundamental frequency of the signal, or on the number of the measured harmonic. The analyzer contains modulator 1, filters 2 and 4 of the lower frequencies, modulator 3, voltmeter 5, frequency multiplier 6, aggregate frequency allocation unit 7, frequency generator 8. 1 il.

Description

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The invention relates to a measurement technique and is intended to measure the amplitude values of the harmonic components of periodic signals.

The purpose of the invention is to expand the frequency range of the first harmonic.

This goal is achieved due to a special spectrum conversion, in which the measured harmonic at the inputs of low-pass filters does not depend on the change in the fundamental frequency of the signal or on the number of the measured harmonic.

The drawing shows a block diagram of the device.

The analyzer contains modulator 1 (additional electronic key), first lowpass filter 2, modulator 3 (electronic key), second lowpass filter 4, voltmeter 5, frequency multiplier 6, total frequency extraction unit 7, frequency generator 8. The output of modulator 1 is connected through a serially connected first filter 2, modulator 3 and second filter 4 connected to the input of a voltmeter 5. The input of modulator 1 is the input of a harmonic analyzer and is connected to the input of a multiplier 6, the output of which is connected to the first input of block 7, the output of which is connected to the control input of the modulator 1. The first and second outputs of the generator 8 are connected respectively to the control input of the modulator 3 and to the second input of the block 7.

The harmonic analyzer works as follows

In the initial state, the multiplication factor of the frequency multiplier 6 is numerically equal to the number of the measured harmonic (for example, K).

The signal under study is fed to the input of the modulator 1 and multiplier 6. At the output of multiplier 6, there is a square wave signal (square wave) with a frequency that is K times the basic frequency (first harmonic) of the signal under study. This signal arrives at the first input of block 7, the second input of which receives square pulses from the first output of generator 8. Block 7 forms output pulses of rectangular shape (square wave) with a frequency equal to the sum of the frequencies of signals received at its inputs. The output of block 7 acts on the control input of the modulator 1.

In modulator 1, the signal under investigation is multiplied by the control signal. Multiplication result

enters the input of filter 2, which extracts a useful signal from it. This signal is fed to the input of the modulator 3, where it is multiplied with a square wave signal (square wave) coming from the second output of the generator 8, the output signal of the modulator 3 is fed to the input of filter 4, which extracts a signal proportional to the amplitude of the K-th output measurable

harmonics accurate to a constant multiplier. Voltmeter 5 measures the magnitude (amplitude, mean value) of this signal. At this point, the measurement of the Qth harmonic is completed.

Thus, the main effect resulting from the implementation of these transformations is that regardless of the frequency of the first harmonic of the signal under study and the number of the measured harmonic, the first and second low-pass filters filter (select) fixed stable frequencies. Consequently, the measurement error depends only on the temporal and temperature stability of the parameters of the elements included in the device and does not depend on the frequency range of the first harmonic of the signal under study, on the number of the measured harmonic and, most importantly, on the frequency characteristics of the filters. This achieves the ability to analyze signals with a wide frequency range of the first harmonic, which is a new feature by which known devices

do not possess.

Claims (1)

A harmonic analyzer comprising a frequency multiplier and a first low pass filter connected in series, a modulator, a second low pass filter, a voltmeter, characterized in that, in order to expand the frequency range of the first harmonic, A series-connected frequency generator and a cumulative frequency selection unit are introduced, as well as an additional modulator, the output of which is connected to the input of the first low-pass filter, and the input 0 is connected to the input of the harmonic analyzer and to the input of the frequency multiplier, the output of which is connected to the first input of the cumulative frequency selection unit, the output connected to the control input of an additional modulator, and the second output of the frequency generator is connected to the control input of the modulator.