SU946003A1 - Device for monitoring amplitude-frequency characteristics of four-terminal networks - Google Patents

Description

(54) DEVICE FOR MONITORING AMPLITUDE-FREQUENCY CHARACTERISTICS OF FOUR-POLES

one

The invention relates to a technique of measurement and control and can be used when checking for compliance with the standards of the temporal frequency characteristics of channels and communication devices.

A device for monitoring the amplitude-frequency characteristics of four-port networks is known, comprising, on the transmitting side, a reference frequency generator, the output of which is connected to the first BXO-JQ of the doubles of the switch, the second input of which is connected to the output of the oscillating frequency generator, and the third input to the first output of the first unit control, the second output of which is connected to the first one of the first key, the output of the switch is connected to the input of the quadrupole, the output of which is on the receiving side through a matching amplifier connected to the first the second key and to the input-20 of the reference frequency filter, the output of which is connected to the first input of the automatic level control unit and to the input of the second control unit, the first

the output of which is connected to the second input of the second switch, the output of which is connected to the input of the voltage conversion unit, the second output of the second control unit, the bluetooth automatic level control unit is connected to another input of the matching amplifier, the counter whose output is connected through the serially connected first decipher, first memory block , the first code converter, the first voltage divider is connected to the first input of the first comparator, the second decoder, the input of which is connected to the output of the counter, and the output through Consequently, the connected second memory block, the second code converter, the second voltage divider are connected to the first input of the comparator, the second input of which is combined with the second input of the first comparator, the outputs of the first and second comparators are connected to the corresponding inputs of the totalizer, the output is connected to the first input match element l3. 394 However, the known device has a low accuracy. And the timing is controlled. The circuit of the invention is to increase the accuracy and reduce the time of control. The delivered circuit is achieved by introducing an additional voltage conversion unit, the first frequency divider, the first pulse shaper, an additional counter, a code-analog converter, the third decipher, and the instantaneous value shaper on the receiving side into the device for monitoring the amplitude-frequency characteristics of the quadrupoles. , peak detector, extremator, shaper of reset pulses, trigger, shaper of gating pulses, second frequency divider, watts swarm pulse shaper, quarter decryptor, logical signal processing unit, while on the transmitting side the output of the first key is connected via a serially connected additional voltage conversion unit, the first frequency divider, the first pulse shaper, an additional counter and a code-analog converter connected to the generator input the oscillating frequency, the output of which is connected to the second input of the first key, the output of the additional counter through the third decoder is connected to another input of the first divider frequencies, on the receiving side, the output of the second key through the serially connected driver of the instantaneous value module of the signal and the peak detector connected to the combined second inputs of the first and second comparators, another output of the peak detector through an extremator connected to the first trigger input, the output of the voltage conversion unit through the sequence the second frequency divider and the second pulse driver, connected to the input of the counter, to the first input of the driver, is strobe-connected. pulses and to the first input of the logical signal processing unit and through the shaper of reset pulses connected to the other input of the peak detector and to the second trigger input, the output of which is connected to the second input of the gating pulse shaper, the output of which is connected to the second input of the logical signal processing unit The output of the counter through the fourth decoder is connected to another input of the second frequency divider 5 and to the third input of the gating pulse generator. The drawing shows a structural electrical circuit of the proposed device. The device for monitoring the four-port characteristics of the four-port network contains on the transmitting side 1 switch 2, oscillating frequency generator 3, first key 4, first control unit 5, additional voltage conversion unit 6, first frequency divider 7, first driver 8 pulses, additional counter 9, third a decoder Yu, a code analogue converter 11 and a reference frequency generator 12, and a second key 14 at the receiving side 13, a reference frequency filter 15, a second control unit 16, an automatic level adjustment block 17 n, voltage conversion unit 18, driver of instantaneous value module 9, peak detector 20, first and second comparators 21 and 22, respectively, adder 23, coincidence element 24, logic signal processing unit 25, second frequency divider 26, reset pulse shaper 27 , trigger 28, gate driver 29, extremator 30, second pulse generator 31, counter .32, first and second decoders 33 and 34, respectively, fourth decoder 35, first memory block 36, first converter 37 of code, first div spruce voltage 38, the second block memory 39, the second code converter 40, a second 41 healer voltage matching amplifier 42, the four-pole 43, The apparatus operates as follows. By the beginning of the measurements, the reference signal from the output of the reference frequency generator 12 is sent via switch 2 to the input of the quadrupole under study 43 by the command of the first control unit 5. From the output of the quadrupole 43 under study, through the matching amplifier 42 and the reference frequency filter 15, the reference frequency signal is simultaneously fed to the inputs of the automatic level control unit 17 and the second control unit 16. The second control unit 16 includes a block 17, changing the transmission coefficient of the amplifier 42 to obtain the nominal level of the reference signal at the output of the latter.

The process of automatically regrouping the gain of the matching usipitep 42 (calibration) eliminates the need to manually set the nominal value of the residual attenuation of the quadrupole 43 under investigation at the reference frequency before starting measurements.

The duration of the calibration is set by the time by the Dam chains of the first control unit 5 (usually does not exceed 0.3–0.4 s).

After the calibration is completed, on the transmitting side 1, at the command of the first control unit 5, the switch 2 is simultaneously switched and the first key 4 is closed. The test signal with a constant level and frequency equal to the minimum frequency of the frequency range of the quadripole 43 under study is simultaneously supplied from the generator 3 to the input of the test, quadripole 43 via switch 2 and to the input of the additional unit 6 through the first key 4.

After a predetermined number of periods of the frequency of the test signal, depending on the duration of the transient processes in the quadrupole 43 under study and determined by the deduction factor of the first frequency divide 7, pulses appear at the output of the first pulse shaper 8, which are added by an additional counter 9. On the code inputs of the converter code - analogue 11c outputs of the additional counter 9 enters the incremental code. From the output of the code-analog converter 11, an oscillating voltage equal to equal voltage steps flows to the modulating input of the oscillating frequency generator 3. With a linear modulation characteristic of the oscillating frequency generator 3, the frequency of the test signal by the step of the modulating voltage is increased by the same value. The magnitude of the frequency increment of the oscillating frequency generator 3 depends on the selected number of controlled points of the amplitude-frequency characteristic of the quadripole 43 under study and is set for a given slope of the modulation characteristic of the oscillating frequency generator 3, the magnitude of the voltage increment at the output of the code-analog converter 11.

In order to shorten the measurement time at a given accuracy, the division factor of the first frequency divider 7 varies depending on the frequency of the test signal using a third decoder 10 connected to the outputs of an additional counter 9 whose output code corresponds to the current frequency of the test signal.

At the receiving side 13, at the command of the second control unit -16, the block 17 is turned off (the value of the transfer coefficient of the matching amplifier 42, which was set during the absorption, is maintained unchanged during the entire measurement period) and the second switch 14 is closed. Now the test signal from the output the studied quadrupole 43 through the calibrated matching amplifier 42, through the second key 14 is fed simultaneously to the input of the imaging unit 19 of the instantaneous signal value module and to the input of the unit 18 pre

formation of tension, prebrascuyu. sinusoidal voltage of the test signal into square pulses.

The signal from the output of the imager 19 is supplied to the signal input of the peak

detector 2O. Peak detector 20 stores the amplitude value of each half-period of the voltage of the test signal and stores it until a reset pulse is generated.

shaper 27 of reset pulses from rectangular pulses from the output of voltage conversion unit 18. The signal from the output of the peak detector 20 is fed to the inputs of the first and second comparators.

The rectangular pulses with the frequency of the test signal from the output of the voltage conversion unit 18 are fed to the second frequency divider 26, the division factor of which at the current frequency of the test signal is equal to coe (| dividing the first frequency divider 7. Through the specified number of periods of the frequency of the test signal, determined the division factor of the second frequency divider 26 at the output of the second pulse generator 31 pulses appear, which are summed

counter 1 32. Since the occurrence of pulses at the output of the pulse driver 31 coincides with the change in the frequency of the test signal, and the frequency of the test signal with each pulse increases by the same amount, the number of pulses recorded by the counter 32 is proportional to the frequency of the test signal and is the digital code of the current frequency. 79 The coefficient of the depenn of the second depot 2b of the frequency varies depending on the frequency of the test signalgg synchronously with the division factor of the first frequency divide 7 with the help of the fourth decoder 35 connected to the output of counter 32. The first and second blocks 36 and 39 of memory are connected to the corresponding the outputs of the first and second decoders 33 and 34, remember, within which tolerance limit is the current frequency of the test signal. These decoders are designed to recognize the code combinations of the counter 32 corresponding to the switching frequencies of the tolerance boundaries. The number of input buses of each decoder is equal to the number of elements of the code combination of the counter (the number of counter triggers). The number of output buses of each decoder and, accordingly, the number of triggers of each memory block is equal to the number of switching frequencies of the tolerance limits. In accordance with the current frequency of the test signal at the outputs of the first and second voltage dividers 38 and 41, voltages corresponding to the upper and lower tolerance limits at this frequency, held by memory blocks, are set using the first and second converters 37 and 40 of the code. Converters code code; Conversion of codes at the outputs of the memory blocks storing information about within which of the tolerance limits the frequency of the test signal is found, into the code necessary to establish the corresponding voltages at the outputs of the first and second voltage dividers 38 and 41 . From the outputs of both Voltage Dividers, corresponding to the upper and lower tolerance limits, are fed to the first inputs of the first and second compilers 21 and 22. A comparison of the amplitude values of the test signal stored by the peak detector 20, and the voltages corresponding to the upper and lower The tolerance limits coming from the outputs of both voltage dividers are made by the first and second comparators 21 and 22. The result of the comparison, through the sum, the torus 23 is fed to the first input of the coincidence element 24. The result of the comparison is read out by means of the pimping impulses produced by the shaper 29 of the gating pulses 3 and arriving at the second input of the coincidence element 24. The gating impulses are generated from a sequence of pulses at the direct output of trigger 28. Each pulse at the direct output of trigger 28 begins after the peak Detector 2O has an amplitude value of the test signal at the moment the latter passes through the extremum. The extraction of the moment of passage through the extremum is carried out with the help of an extremizer 30. The pulses from the extremator's output arrive at the input of the trigger 28 and translate it into a single state. The pulses at the output of the trigger 28 end each time at the beginning of the next half period of the test signal. The return of the trigger 28 to its original state. carried out with the help of pulses from the output of the former 27 of the reset pulses. To increase the noise immunity of the device, the conclusion about the compliance or non-compliance with the established norms of the amplitude-frequency characteristic of the studied quadrupole at this frequency is made only after the results of the comparison of the amplitude-frequency characteristic of the tested quadripole 43 are matched to the tolerance limits in several half-periods of the test signal using the logic block 25 comprising a storage device for comparing the results of all Mykh half-cycles of the test signal. Before starting measurements at each controlled point of the amplitude-frequency characteristic, the information stored in the storage devices of the comparison results of the logic processing unit 25 is erased using pulses from the output of the second pulse generator 31. To eliminate an error that may occur due to a malfunction of the WTO. Frequency Divider 26 (impulse noise, short-term signal loss due to interference or short-term increase in residual attenuation in a quadrupole under test), the comparison results are read in half-periods of the test signal spaced from the beginning and end of measurements at each counterpoint by the interval providing steady-state oscillation mode in the studied quadripole

43 with impulse noise (gradually leads to a shift of the comparison time to the beginning of measurements at a given controlled point), the reliability of the comparison result with a short signal loss (leads to a comparison of the comparison time to the end of measurements at this controlled point).

Since the number of half-periods of the test signal at each controlled point varies and depends on the frequency. test signal, then the moments of reading the comparison results depend on the frequency of the test signal. Therefore, a frequency divider with a time division factor is introduced into the shaper 29, which changes synchronously with the dividing ratio of the second frequency driver 26 and is also controlled by the fourth decoder 35. Information about the start of measurements at a controlled point arrives at the shaper of 29 pulses from second shaper 31 pulses.

Thus, the positive effect of the implementation of the proposed device is as follows.

Since the frequency of the frequency-modulated oscillation used as a test signal varies discretely and the duration of measurements at each controlled point of the amplitude-frequency characteristic exceeds the duration of the transient, the latter practically does not affect the shape of the resulting amplitude-frequency characteristic, which greatly increases the accuracy of control . In addition, the time control of the amplitude-frequency characteristics using the proposed device is significantly less.

Claims (1)

1. USSR author's certificate No. 649143, Krt. H 04 B 3/46, 1977 (prototype). W-.Vj-. r VQ " “R