SU552569A1 - Phase fluctuation measuring device - Google Patents

Description

one

The device for measuring phase fluctuations can be used in the radio measuring technique.

A device for measuring phase fluctuations is known, which includes frequency detectors, low-frequency amplifiers, a subtractive element and an indicator.

However, this device does not have sufficient reliability.

It is also known a phase fluctuation measurement device comprising a phase detector, one of whose inputs is connected to one of the outputs of a reference crystal, the output of a phase detector is connected to the inputs of a spectrum analyzer and a low-frequency filter, the output of which is connected to one of the inputs of a reference crystal.

Measurement of phase fluctuations is reduced to their conversion to amplitude, which are then measured by a spectrum analyzer. However, a similar scheme of the meter makes it impossible to measure the small level of these fluctuations relative to the carrier, since the steepness of the transformations of phase fluctuations into amplitude fluctuations is not known.

The aim of the invention is to extend the measurement range towards small fluctuations and increase measurement accuracy.

This is achieved by the fact that a phase fluctuation measurement device containing a phase detector, one of whose inputs is connected to one of the outputs of a reference crystal oscillator, is output of a phase detector connected to the inputs of a spectrum analyzer and a low frequency filter, the output of which is connected to one of the inputs of a reference crystal oscillator It is equipped with a sound generator, a deviometer, a frequency modulation index meter and a fluctuation power indicator, and another input of the reference crystal oscillator through tion connected deviometr and Meter

The frequency modulation index is connected to the fluctuation power indicator, the outputs of the sound generator are connected separately to the second inputs of the reference crystal oscillator and the frequency modulation index meter.

The drawing shows a structural diagram of the meter phase fluctuations.

The meter contains a phase detector 1, a reference generator 2, a low frequency filter 3, a spectrum analyzer 4, a sound generator 5, a deviometer 6. A meter 7 of the frequency modulation index, an indicator 8 of fluctuation power. Works meter slsduiyii1m way.

The signal under study is fed to one of the inputs of phase detector 1, and the signal from the output of reference oscillator 2 goes to the second input. The voltage from the output of phase detector 1 is fed through low-pass filter 3 to oscillator 2 and performs phase frequency tuning without changing oscillator phase fluctuations .

The output voltage of phase detector 1 is a measure of phase fluctuations whose speed exceeds the passband of filter 3. It is measured by spectrum analyzer 4 by comparing it with the power of the side component of the reference frequency modulation carried out with the aid of sound generator 5. For this From one of the outputs of the sound generator 5 to the reference generator 2, the modulating sinusoidal voltage of a certain amplitude and frequency is applied. Then, using the deviometer 6, the value of the deviation of the reference modulation at the output of the reference oscillator 2 is measured, and a voltage proportional to the measured deviation is applied to one of the inputs of the meter 7 of the frequency modulation index. To the second input of this meter, the voltage of the generator 5 is applied. From the output of the meter 7, a voltage proportional to

t,

them

where A is the frequency deviation;

QH is the frequency of the modulating voltage, and is supplied to the power indicator 8, for example, a quadratic voltmeter with an averaging (integrating filter). As is well known, the contribution to the full spectrum of a signal made by standard modulation with small indices m is equal to

"

with

Byo RM power fluctuation; introduced by reference modulation;

PC is the signal power, t is the index of the reference modulation. R

Thus, the ratio value is

PC

determined by the additional circuit introduced, but at the same time the lateral components of the reference modulation pass through

the same transformations as the phase fluctuations of the generator under study (detection, amplification). This makes it possible to determine a small level of phase fluctuations, comparing them in the spectrum analyzer 4 with the known

level side modulation component.

Claims (1)

Invention Formula A phase fluctuation measurement device containing a phase detector, one of the inputs of which is connected to one of the outputs of the reference crystal oscillator, an output A phase detector is connected to the inputs of a spectrum analyzer and a low frequency filter, the output of which is connected to one of the inputs of a reference crystal oscillator, characterized in that, in order to expand measurement range in the direction of small fluctuations and improved measurement accuracy, it is equipped with a sound generator, a deviometer, a frequency modulation index meter and a fluctuation power indicator, and another output of the reference crystal oscillator is connected via a series-connected deviometer and a frequency modulation index meter to the fluctuation power indicator, sound generator outputs separately connected with the second inputs of the reference crystal oscillator and the frequency modulation index meter.