SU1356242A1 - Device for checking voice-frequency communication channel - Google Patents

Abstract

Invention m. used to assess the quality of the tone frequency channels for data transmission. Pel invention - improving the accuracy of control. The device contains sensor 1 test signals and receiver 2. Sensor 1 contains a carrier frequency generator (LF), phase modulator 4, trigger 5, modulating frequency generator 6, amplitude modulator 7, switch 8, receiver 9 of the worst combination code ( KNK), control block 10. The receiver 2 contains the amplifier I1, the modulator 12, the low-frequency generator 13, the filters 14 and 21, the signal envelope detector 15, the encoding unit 16, the memory block 17, the subtraction unit 18, the sampling value fixer 19, the rectifier 20, the phase signal detector 22, trigger 23, clock synchronization unit 24, frame alignment unit 25, control unit 26, divisor 27 numbers, indicator 28, driver control unit 29, SFC transmitter 30, distributor 32 characters of the signal. 2 Il. (L with SP O) of th “th FIG.

Description

eleven

The invention relates to telecommunications and can be used to assess the quality of voice frequency (PM) channels for data transmission.

The purpose of the invention is to improve the accuracy of control.

Figure 1 shows the structural electrical circuit of the devices; in fig. 2 - 3 - timing charts of the device.

A device for monitoring a communication channel of a tonal frequency contains a test signal of 1 test signals and a receiver of 2 test signals. The sensor includes a non-existent frequency generator 3, a phase modulator 4, a trigger 5, a modulating frequency generator 6, an amplitude modulator 7, a switch 8, a worst-combination code receiver 9, and a control unit 10. The receiver 2 includes an amplifier 11, a modulator 12, a carrier frequency generator 13, a first filter 14, a signal envelope detector 15, an encoding unit 16, a memory unit 17, a subtraction unit 18, a sampling value fixing unit 19, a rectifier 20, second filter 21, phase detector 22, trigger 23, clock synchronization unit 24, frame alignment unit 25, control unit 26, divider 27 numbers, indicator 28, driver control unit 29, worst combination code transmitter 30, driver 31, signal distributor 32 characters .

Forward and reverse links are designated respectively 33 and 34,

The device works as follows.

The measurement involves the forward and reverse direction of a two-way communication channel, and the measurement process consists of three stages. At the first measurement stage, the measuring pulse sequence is transmitted from sensor I via forward link 33 to receiver 2. After receiving this pulse sequence, the worst combination is generated for this channel, information about which is transmitted through the reverse link 34 from the second measurement step receiver 2 to sensor 1. In the third stage of measurement, the worst combination, measurement and measurement are transmitted over the forward link 33.

the operation of which allows the channel to be estimated by the parameter of the maximum value of intersymbol interference with high accuracy and reliability.

In the proposed device, a sequence of phase-modulated pulses of duration t is used as a test signal.

10 whose amplitude varies depending on the measurement stage and the frequency characteristics of the channel under study.

On the first step of measurement, the W-element phase-modulated sequence is transmitted via the right 15th communication channel 33, the amplitude of the average impulse of which is increased by 30% compared to other pulses of sequence 20,

From the output of the direct communication channel, 33 test signals through amplifier 11 are fed to a phase detector 22, for which operation, a 25 MOS reference oscillation is needed. It is generated from the received signal due to the action of the rectifier 20, the filter 21 and the trigger 23. At the output of the phase detector 22, pulses are generated to ensure the operation of the clock synchronization unit 24 and the frame synchronization unit 23, the output signals of which determine the operation conditions of the unit 26 control by agreement of the operating moments of the rest of the receiver 2 - blocks 16,17,19, 27 and 29.

The test signals from the output of amplifier 11 are fed to the input of the modulator 12, in which the signal spectrum is transferred to the high-frequency region due to the generator 13, which, together with the filter 14, eliminates distortion due to the low frequency of the carrier wave.

The amplitude of the voltage envelope rectified by the detector 15 is varied in accordance with the response of the communication channel response gQi to a single element of the signal. The time dependence of this signal minus the constant component is shown in the drawing (Fig. 3), where S, 3. BO, S p Sj ..,. marked according 55

well ahead and lagging responses. The rectified voltage from the output of the detector 15 of the signal envelope is supplied to coding block 16, to the amplitude of the rectified by the detector 15 of the voltage signal envelope changes in accordance with the response of the communication channel to a single element of the signal. The time dependence of this signal minus the constant component is shown in the drawing (Fig. 3), where S, 3. BO, S p Sj ..,. marked according

well ahead and lagging responses. The rectified voltage from the output of the detector 15 of the signal envelope is fed to coding block 16, to 3

In the course of which, a numerical expression of the amplitude of the test signal is obtained, which is subject to further mathematical processing.

Mathematical signal processing primarily consists of eliminating the constant component, performed in subtraction unit 18, as well as memorizing, using the fixing unit 19, the readout value of the maximum amplitude of a single signal element and, finally, determining the sign of leading and lagging signal responses, which A 32-character signal is perceived by the valve

First, only the sign of the response is determined, and then in the third measurement step, the maximum intersymbol interference is calculated. In order for all measurements of the signal to have a positive value at the reference time, in this measurement, the envelope of the worst combination shown in FIG. 4 is selected for the responses in FIG. 3. These operations are performed in the imaging unit 31, and then the combination is encoded and transmitted to the sensor 1 of the test signals using the transmitter of the worst combination code transmitter 30,

Fig. 5 shows the time dependence of the transmitted voltage of the worst combination. The timing of the operation elements of the transfer of the worst combination is accomplished by the driver control unit 29.

In the second measurement step, the worst-case combination as a phase-modulated variable amplitude sequence is transmitted over the reverse link and received by the worst-combination code receiver 9, and the time of receipt of the phase-modulated sequence is recorded in sensor control unit 10. A carrier frequency generator 3 and a modulating frequency generator 6 together with a trigger 5 ensures the operation of a phase modulator 4, the output of which produces phase-modulated sequences with a constant signal amplitude fed to amplitude modulator 7,

The amplitude modulator 7 includes extension cords with attenuation

562424

3, 6 and 6 dB, switched on and off depending on the measurement stage and the worst combination code with switch 8. In the PM quality control device, the main external parameters of the sensor of test signals should be characterized: carrier frequency f c. 1Q 1800 Hz; modulation frequency F

A10A

 699 Hz; relative levels of the test signal: during transmission +1 P tn O dB; with a POTN transmission of 3.6 dB; at

Transmission -1 P „-9.6 dB.

The worst-case combination in the third measurement step is transmitted via the forward link from sensor 1 to receiver 2 of test signals. The reception feature of the worst combination from the reception of the pulse sequence is that the counted total value of the intersymbol interference

is stored in block 19 of fixation of sampled values, and then the values of the signal obtained by fixing are fed to the divisor 27 numbers, the result of the calculation — the quotient — is fed to the indicator 28,

Claims (1)

Invention Formula 35 A device for monitoring a communication channel of a tonal frequency, comprising a sensor of test signals and a receiver of test signals comprising a series-connected rectifier, a first filter, a trigger 4Q and a phase detector, the second input of which is connected to the rectifier input, an amplifier connected in series, the output of which is connected to the rectifier input, and the input is with the output of the forward link channel, modulator, second filter, envelope detector, coding unit and a subtraction unit, clock and frame synchronization blocks, whose inputs are connected to the output of the phase detector, a memory unit, a control unit, the first and second inputs of which are connected respectively to the outputs of the clock synchronization unit and the cyclic block f-f. synchronization, and the first and second outputs are connected respectively to the input of the coding unit and to the first input of the memory unit, the second input of which is connected to the output of the coding unit, and the output is connected to the second input of the subtraction unit, a carrier frequency generator, the output of which is connected to the second input modulator, indicator, characterized in that, in order to increase the accuracy of control j, serially connected characters distributor, driver and transmitter of the worst combination code, therefore, the connected block of fixation of the reference values, the input of which is connected to the output of the subtraction unit and the first input of the distributor of characters, and the divisor of the numbers, the output of which is connected to the indicator input, and the second input connected to the third code of the control unit, the fourth output of which is connected to the second input the block of fixing the readings, the control unit of the generator, the input of which is connected to the fifth output of the control unit, and the first, second and third outputs are connected respectively to the second input Q g 0 five distributor, driver and, worst-case code transmitter, the output of which is the reverse link channel input, and the test signal sensor contains, in series, a modulating frequency generator, a trigger and a phase modulator, serially connected, the worst-case code receiver, whose input is reverse link output, a switch and an amplitude modulator, the second input of which is connected to the output of the phase modulator and the second input of the switch, and the output is a forward link home, a carrier frequency generator, the output of which is connected to the second input of the phase modulator, a control unit, the input of which is connected to the receiver input of the worst-case code, and the first and second outputs are connected to the inputs of the carrier and modulating frequencies and the third respectively switch input. fo. 2 IG QS о ц о-5 Og Oi o-i 0,2 o-s о.ц Fy Editor M. Bandura Compiled by Sh. Evn n Tehred M. Khodanych Order 5814/56 Circulation 636 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 FIG. five Proofreader “Patay”