SU1383283A1 - Device for measuring non-identity of phase delay time - Google Patents

Abstract

The invention relates to the field of radio measurements and serves to increase the accuracy of measuring the nonidentity of the phase time delay of two-channel devices. The device contains high-frequency and low-frequency oscillators 1 and 2, switch 6, mixers 10 and 15, low pass filters 11 and 13, phase discriminator 19 and indicator 20. Measurement accuracy is mainly determined by the relative error of indicator 20 and is achieved by introducing a balanced modulator 3, bandpass filters 4 and 5, wideband amplifier 8 with automatic gain control, limiting amplifiers 12 and 17, low pass filters 16 and 18, which allow to stabilize the amplitude of the test signal from the upper it and the lower side frequencies, and the amplitude of the informative signals. This, in turn, reduces the amplitude-phase error. In addition, the use of two channels in the device with nodes of identical technical characteristics provides compensation for additionally introduced or phase shifts. 1 il. (C sl

Description

The invention relates to radio measuring technology and can be recommended for measuring the nonidentity of the phase delay time of two-channel devices with lumped and distributed parameters.

The purpose of the invention is to improve the accuracy of measuring the nonidentity of the phase time delay of two-channel devices.

The drawing shows a block diagram of a device for measuring the nonidentity of the phase delay time

The device contains a high-frequency generator 1, a low-frequency generator 2, the output of which is connected to the first input of a balanced module 3, the second input of which is connected to the code of the high-frequency generator 1, and the output to the inputs of bandpass filters 4 and 5, the outputs connected to the first and second inputs switch 6, the control input of which is connected to the output of the frequency divider 7, the input of which is connected to the output of the low-frequency generator 2, the output of the switch 6 through successively connected broadband amplifier 8 with automatic tion gain control, vy first investigated mixer circuit 10, the first filter 11, a low pass, the first limiter-amplifier 12 is connected to the input of the second lowpass filter 13. The output of the broadband amplifier 8 is connected through the second test circuit 14, the second mixer 15, the third low pass filter 16, the second limiting amplifier 17, the fourth low pass filter 18 to one input of the phase discriminator 19, the second input of which is connected to the output of the second filter 13. low pass, and the output - with the input of the indicator 20.

The device works as follows.

The high frequency signal U, (t) Um, cos (wt + H (,) and the low frequency signal U (t) and cos (jt + qi) from the outputs of generators 1 and 2 are fed to the inputs of the balanced modulator 3, the output signal which has the form

and, (t) Un ,, (cot + h o) cos (at + q) (co-Q) t + qio-Cp; + cos (a + 9) t +

(one)

where tvpo is the initial phase of the high-frequency and low-frequency signal

Yu

tS

20 25 jq 40

45

50

55

fishing and

W

 and. the resulting amplitude of the output signal.

Signal (1) is simultaneously fed to the inputs of bandpass filters 4 and 5, which select the upper and lower sidebands, i.e.

U4 (t) (u + n) t + Cfo + q; + cp, - / (2) U (t) (p-0) t + (f ,, p)

where Cf, and qi, phase shifts introduced by bandpass filters 4 and 5, Signals (2) and (3) arrive at the first and second inputs of switch 6, which is switched by low-frequency pulses generated from the signal of low-frequency generator 2 using a splitter 7 frequencies and incoming to the controlled input of the switch 6. In the first half-period of switching, the signal (2) from the output of the switch 6 is fed through a broadband amplifier 8 with automatic gain control to the input of the first circuit under study 9. the output of which is

U5- (t) U cos (u + d) t + C + Cfё + Cf, - 35 -c, + cf,, - (4)

where tf is the phase shift introduced

The circuit under study is 9j tf, the phase shift introduced by the wideband amplifier 8 with automatic gain control. The signal (4) is fed to the first input of the first mixer 10, where it is mixed with the high-frequency signal U) (t) fed to its second input from the output of the high-frequency generator 1. Signal at the output of the mixer 10 using a low-pass filter 11 expressed by the formula

Ue (t) UmeCOsCnt + Cp + Cf, -, + cp) ,, (5)

where is the phase shift introduced

11 low pass filter. The signal (5), in which the information q) is enclosed about the phase shift of the circuit 9 under study, enters through

the limiting amplifier 12 for the purpose of normalizing the amplitude to the input of the low-pass filter 13, which is intended to eliminate the influence of higher harmonics on the measurement result. The output signal of the filter 13 of the lower frequencies at the first input of the phase discriminator 19, has the form

UyCt) (nt + cf + 4, -4, +

+ H s + H 4 + M 5 + 0 b), (6)

where cfg and tfg are the phase shifts introduced by the first limiting amplifier 12 and the second low-pass filter 13.

At the same time, in the first half-cycle of switching, the signal (2) from the output of switch 6 is fed through a broadband amplifier 8 with automatic gain control to the input of the second circuit 14, the output signal of which is

UgCt) (Q + Q) t + q o + + Q o + q; -4 i + q ,, (7)

The signal (7) is fed to the first input of the mixer 15, where it is also mixed with the high-frequency signal U, (t) fed to its second input from the output of the high-frequency generator 1. The differential frequency signal allocated to the output of the mixer 15 can be represented as

U, (t) U cos (Qt + (, - Cf, + q, + q l,), (8)

where Cp is the phase shift introduced by the lowpass filter 16.

The signal (8), in which information is enclosed (about the phase shift of the circuit 14 under study, is fed through the second amplifier-limiter.17 in order to normalize the amplitude to the input of the low-pass filter 18, intended to eliminate the effect of higher harmonics on the measurement result. The output the signal of the filter 18. the lower frequencies supplied to the second input of the phase discriminator 19, has the form

and, o (t) Um jCosCQt + q q, - - + 4} +4 l + cf; + Cf J, (9)

where tp j and Cf are the phase shifts introduced by the amplifier-limiter 17 and the filter of 18 ngs frequencies.

83283.

After comparing the signals (6) and (9) in phase in the phase discriminator 19, a constant voltage is released at its output, varying in proportion to the difference, i.e. non-identity phase time delay G () / is measured by indicator 20, the scale of which is calibrated in units of phase delay time.

In the second half-period of commutation of switch 6, the inputs of the studied circuits 9 and 14 are applied simultaneously.

15, the signal of the lower sideband described by expression (3), the principle of operation of the device is similar to that considered.

The proposed device for measuring the nonidentity of the phase time delay compared to the known method provides a measure of the nonidentity of the phase time delay with high accuracy, which is mainly determined by the relative error of the indicator used. This advantage is achieved due to the use of additional nodes in the device, which allow stabilizing both the amplitude of the test signal with the upper and lower side frequencies and the amplitude of the informative signals, which reduces the amplitude-phase error. In addition, the use of two channels in the device with nodes of identical technical characteristics provides compensation for the phase shifts that they additionally introduce and contributes to the fulfillment of the set goal.

Claims (1)

Invention Formula A device for measuring the non-identity phase delay time, containing a high-frequency and low-frequency oscillator, a switch, terminals for connecting the first circuit under study, the first and second mixers, the first and second low-pass filters, the phase discriminator and the indicator, the output of the first mixer being connected to the input of the first lower filter frequency, the first input of the second mixer is connected to the output of the high-frequency generator, characterized in that, in order to increase the measurement accuracy non-identical phase time delay of two-channel circuits; a balanced modulator, two bandpass filters, a frequency divider, a wideband amplifier with automatic gain control, terminals for connecting the second circuit under study, two limiting amplifiers, the third and fourth low-pass filters, and balanced the modulator inputs are connected to the outputs of the high-frequency and low-frequency oscillators, and the output simultaneously with the inputs of the first and second band-pass filters are connected to the outputs the first and second inputs .kommutatora controlling e my11 input of which via a frequency divider coupled to an output Nogo low-frequency oscillator output of the switch via a broadband amplifier with automatic gain control 0 five The single terminal of the first circuit under study is connected to the first input of the first mixer, the second input of which is connected to the output of the high-frequency generator, the first limiting amplifier is connected to the output of the first low-pass filter, and the output through the third low-pass filter - with the first input of the phase discriminator, the second input of which is connected via a fourth low-pass filter connected in series, a second amplifier-limiter and Ora lowpass filter with the output of the second mixer, a second input coupled to the second output terminal to the circuit, this output .If phase discriminator is connected to input indicator.