SU759973A1 - Device for measuring oscillation frequency deviation - Google Patents

Description

The invention relates to a measuring technique and can be used to measure the parameters and characteristics of deviations of the frequency of the oscillations from the nominal values without using sources of the reference frequency.

A device is known for measuring fluctuations in the frequency of oscillations from but-, θ minal values, containing phase-locked loops and variable frequency generators [ί}.

A disadvantage of the known device is its complexity.

A device is known that contains a two-channel comparator connected in series, the inputs of which are the device inputs, a frequency multiplier, a delay line, a 20-ee detector, a low-pass filter and a recording device (measuring unit) (D ..

Its disadvantages are the low frequency resolution, 25 due to the small frequency multiplication factor, which cannot be made greater than the maximum permissible value and the need for a reference oscillator. thirty

2

The purpose of the invention is to increase the measurement accuracy and simplify the device.

This goal is achieved by the fact that in a device for measuring fluctuations in the frequency of oscillations, containing a series-connected phase detector, a low-pass filter and a measuring unit and series-connected K-frequency converters, each of which consists of a series-connected mixer and multiplier, synthesizer, delay line and input multiplier, the output of the K-th converter is connected to the first input of the phase detector, the second input of which is connected to the output of the input signal frequency multiplier ala, with _b · synthesizer first input and to the input of the delay line, whose output is connected to the signal input of the first inverter and the input of the heterodyne mixer frequency converters are connected to the output of the synthesizer, a second input coupled to the input of the multiplier input signal,

The drawing shows a block diagram of the device. ·

759973

The device contains an input signal multiplier 1, a delay line 2, a phase detector 3, a low-pass filter 4, a measuring unit 5., a synthesizer 6, converters 7-1-7 to a frequency, each of which contains a mixer 8 and a multiplier 9, input ³ bus 10.

Multipliers 1.9 frequencies can consist, for example, of a chain of resonant (or parametric) multipliers, _n frequencies of sinusoidal oscillations with '® common frequency multiplication factor,

equal to l, the amplitude of the voltage at the output of which does not depend on time and remains constant. In particular, multipliers of two vibrations can be used as frequency multipliers, loaded and band-pass filters, whose tuning frequency is equal to twice the frequency of the signal under study.

As a delay line 2, an analogue partitioned, tunable, or non-tunable delay line can be used.

Mixers 8 are a frequency mixer or a multiplier of two oscillations, the load of which is a bandpass filter, the average tuning frequency of which is equal to the nominal frequency of the signal under study, and the resonant amplifier, the amplitude of the output voltage of which does not depend on time and remains constant.

As the phase detector 3 can be used a balanced phase detector, a mixer or a multiplier of two oscillations with a low pass filter or an adder and an amplitude detector with a low pass filter.

The operation of the device for measuring fluctuations in the frequency of oscillations can be represented as follows.

Signal to be investigated

. £ (1) - ^ (1) ^^ 1 ^ (¼) ^

where Α (ι) is the signal amplitude; ω ₀ is the signal frequency;

F - phase signal

comes in the form of oscillation with a constant amplitude to the input of frequency multiplier 1, in which it is converted into an oscillation of the form

15

20

25

thirty

35

40

The low pass filter 4 is a low noise active low pass KS filter with a necessary transmission coefficient in a given frequency band. . .. '45

Measuring unit 5 may contain a voltage amplitude measurement node, a measurement of the effective voltage value, amplitude, phase and energy spectra analyzers or a device for calculating Fourier coefficients in a trigonometric basis and other computing devices.

The synthesizer 6 comprises a mixer or multiplier frequency oscillation of two ^{33-oscillations} whose load is a bandpass filter, whose average frequency setting in the (n-1) times the nominal frequency of the signal, the resonant amplifying limiter 60 and the output from the dispenser to the outputs of the amplitude voltage on which does not depend on time and remains constant. ,five

/(+.)- А + пф (1) + л.у

where η is the frequency multiplication factor and (X is the phase shift introduced by the frequency multiplier 1 to the second input of the synthesizer 6.

Oscillation T; (c) from the output of the frequency multiplier 1 is fed to the first input of the synthesizer 6 and through the delay line 2 in the form of oscillation

Г, (1 -1 = А тт [η ω ₀ 1 + and Ф (ί -1 _& ) + <\],

where is the delay time of line 2, on

signal input of the first mixer 8 of the converter. As a result of this, the oscillations of the form are formed on all K outputs of the synthesizer b

n _g <b) = ΑδΑη ^ η- ι) ω _ο 1 + (P- ήΡ (ΐ) + ^ _τ ],

which go directly to the heterodyne inputs of the respective mixers 8, and at the output of the mixers

8 oscillation is formed

P _b (1) 'A5, pGi ₀ 1 + ^ (1-1,) - ^ - 1) ^ (1) + ^,

which is fed to the input of the multiplier

9 frequency, which is converted to oscillation of the form

^ (1) -Α5) η [ηω _ο 1 ++ 1 ^^ (1-1 ^) - ^ (9-1) ^ (1) + ^]. . Swing

^g GM1 ^1A 5'π [υ _ο ν ι Ich (1-g _s) = η * ψ (ι) + ^ ( 1) + ^^ 0

from the output of the mixer 8 is fed to the input of the multiplier 9 K-th frequency converter 7, in which, is converted into oscillation

р2к ₊ 2 (1) "А51п {pi» ₀ 14 η ^{Λ +} ν (ΐ-1 ^) - η ^ο ν (ΐ) +

⁺ pP (1) + <* _Ш2 ],

then coming to the first input of the phase detector 3. In the phase detector 3, the desired result is formed at its output

where a is the coefficient of proportionality. further coming through filter 4

.75-9973

low frequencies to the input of the measuring unit 5, in which it is further processed and the necessary parameters and characteristics are recorded that give full information about the frequency deviations of the signal under study from its nominal value.

Thus, the introduction of new connections favorably distinguishes the proposed device for measuring deviations of the oscillation frequency from the known ones, since it allows to significantly increase the frequency resolution without using a reference oscillator.

Claims (1)

Claim . A device for measuring fluctuations in the frequency of oscillations, containing a series-connected phase detector, a low-pass filter and a measuring unit and series-connected K-frequency converters, each of which consists of The mixer and multiplier, the synthesizer, the delay line and the input signal multiplier are connected in series, characterized in that in order to increase the measurement accuracy, the output of the K-th frequency converter ^{5 is} connected to the first input of the phase detector, the second input of which is connected to the output of the input frequency multiplier signal, with the first input. the synthesizer and the input of the delay line, the output of which is connected to the signal input of the first frequency converter, and the heterodyne inputs of all mixer mixers of the frequency converters are connected to the output of the synthesizer, the second input of which is connected to the input of the input signal multiplier.