SU484471A1 - The method of measuring the magnitude of the phase angle - Google Patents

Description

one

The invention relates to the field of phase-measuring technology and can be used to create meters for small phase shifts between two electrical oscillations in a wide frequency range.

A known method for measuring the magnitude of the phase shift of a periodic sequence of rectangular pulses relative to a reference pulse train formed from a reference harmonic signal. However, the known method has insufficient measurement accuracy.

The purpose of the invention is to improve the measurement accuracy. For this, a sequence whose pulse duration is proportional to the current phase difference is formed from the input pulse sequence and the reference sequence, one of the harmonics of the repetition frequency is selected from this sequence. After amplitude detection, this harmonic is used as a control voltage, causing a change in the delay time of pulses of constant duration, which follow a frequency that is N times less than the frequency of the measured voltage. From the sequence of the mentioned pulses of constant duration, the Lth harmonic is selected, then the magnitude of the phase shift of the given harmonic is measured relative to the harmonic harmonic signal. A harmonic of the repetition frequency is selected that is closest to one nz transition frequency of the envelope of the amplitude spectrum through zero. The drawing shows a block diagram of one of

possible implementation of the proposed method.

The block diagram contains drivers 1, 2 in the input and reference voltage channels; 3 matches, pulse duration

the output of which is proportional to the current phase difference between the input and reference voltages; selective system 4 tuned to the pulse frequency harmonic closest to the frequency

f - / A 1 94.- - fo

/ - I A - ii o ,. . ., O - 7,

Ф - initial phase difference); amplitude detector 5 (accurate rectifier); divider 6

pulse frequency L times; time modulator 7, which converts the change in control voltage from the output of the amplitude detector to changes in the length of the voltage generated by the pulses; generator 8 pulses of constant duration, operating in standby mode; an electoral system 9 tuned to a harmonic of a pulse duration of a constant duration with the number L, the output voltage of which

is the end result of a conversion, and a standard phase meter 10 for measuring amplified phase shift changes.

The device that implements the proposed method works as follows.

When the coincidence of 3 square-shaped pulses arrives at the output of the electoral system 4, the n-th harmonic voltage appears at its output closest to one of the transition frequencies of the envelope of the amplitude spectrum through zero. Changes in the output voltage of the selective system, proportional to changes in the phase difference at the input, after amplitude detection (accurate rectification) by detector 5, cause proportional changes in the pulse duration at the output of the time modulator 7, which is triggered by pulses of L measured frequency times voltage. The back edges of the output pulses of the time modulator start a pulse generator of constant duration 8, the output pulses of which are fed to the input of the electoral system 9, which separates the harmonic of the frequency of the measured voltage divided by L times, i.e., the voltage of the measured frequency. The change in the phase of this voltage relative to the reference voltage significantly exceeds the change in the phase of the input voltage relative to the reference voltage, so

the resolving power of the phase meters increases, and, consequently, the accuracy of the phase measurements by the proposed method.

Subject invention

Claims (2)

1. A method for measuring the magnitude of the phase shift of a periodic sequence of rectangular pulses relative to a reference pulse sequence formed from a reference harmonic signal, characterized in that, in order to improve the measurement accuracy, a sequence whose pulse duration is proportional to the current difference is formed from the input pulse sequence and reference signal of the phases, one of the harmonics of the repetition frequency is extracted from this sequence, which, after amplitude detection and used as a control voltage, causing a change in the delay time of a pulse-in constant duration, following with a frequency that is N times smaller than the frequency of the measured voltage, from the sequence of the said pulses of constant duration, the N-th harmonic is measured, then the magnitude of the phase angle of a given harmonic relative to the reference harmonic signal. 2. A method according to claim 1, characterized in that the harmonic of the repetition frequency is selected which is closest to one of the transition frequencies of the envelope of the amplitude spectrum through zero.