SU1483651A1 - Device for evaluating quality of communication channel - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to improve the accuracy of assessing the quality of the communication channel. The device contains a mixer 1 frequency, band-pass filter 2, adder 3, demodulators 4 and 18, adders 5 and 19 modulo two, el-And 6 and 20, counters 7 and 21 errors, indicators 8 and 22, compensation block 9, amplitude detector 23, integrator 24, attenuator 25, manipulated grs 26, grs 27 and 30 pulses, clock gp 28, phase shifter 29, shaper 31 clock pulses, 32 reference frequency generator unit and control and synchronization unit 33. The goal is achieved by predicting the quality of the communication channel occupied by the interference. Based on the results of the analysis, a decision is made to transfer the radio link to a new frequency channel, in which the quality assessment is the highest. The device in accordance with claim 2 of the file is characterized by the performance of a compensation unit 9, a feature of which is the calculation of the correction function of the oscillations. 1 h. item f-ly, 1 ill.

Description

The invention relates to radio engineering and can be used to select a channel in radio communication systems operating in the modes of frequency and relative phase shift keying and using adaptive interference compensation devices to protect against interference.

The purpose of the invention is to improve the accuracy of the assessment by predicting the quality of the communication channel occupied by interference.

The drawing shows the structure of the bandwidth of the information receiving path to the first input of adder 3. At the same time, the manipulated control voltage from the manipulated generator 26 with the manipulation characteristics identical to the received signal is supplied to the second input of the adder 3. The pulses for manipulating the manipulated oscillator 26 with a variable duty cycle simulating the signal are generated by pulse generators 27 and 30 with a speed equal to the manipulation speed; the adopted electrical circuit of the device 15 for evaluating the quality of the communication channel.

The device comprises a frequency mixer 1, a bandpass filter 2, an adder 3, a first demodulator 4, a first adder 5 modulo two, a first element And 6, a first error counter 7, a first indicator · 8, a compensation unit 9, consisting of the first adder 10, the first delay element 11, the first quadrature filter 25, the first inverting amplifier 13, the second adder 14, the second inverting amplifier 15, the second quadrature filter 16 and the second delay element 17, the second J0 demodulator 18, the second adder 19 modulo two, the second element And 20, second count error indicator 21, second indicator 22, amplitude detector 23, integrator 24, attenuato 25, manipulated generator 26, first pulse generator 27, clock generator 28, phase shifter 29, second pulse generator 30, clock generator 31, generation block 32 support - 40. frequencies, block 33 control and synchronization.

The device operates as follows.

From the intermediate frequency output of the monitored radio receiver, the measured interference voltage is supplied to the first input of the mixer 1, the second input of which supplies the local oscillator voltage from the block 32 for forming the reference frequencies. The sequence of setting the local oscillator frequencies during analysis is carried out according to the commands received from the control and synchronization unit 33.

From the output of the mixer 1, the voltage of the differential frequency is supplied through a bandpass filter 2, the bandwidth of which is consistent with the signal.

The control voltage level is proportional to the average noise level and is set by the controlled attenuator 25. In this case, the initial level setting should ensure a minimum of control sequence distortions. The control voltage supplied to the attenuator 25, is formed by the amplitude detector 23 and the integrator 24 from the interference voltage supplied to them from the intermediate frequency output of the controlled radio. Exposed to interference in the adder 3, the frequency or phase-shifted signal is supplied to the demodulator 4 and simultaneously to the compensation unit 9. The rectangular pulses allocated by the demodulator 4 are fed to the first input of the adder 5 modulo two. To the second input of the adder 5. modulo two simultaneously fed pulses directly from the output of the second pulse generator 30. Moreover, both pulse generators 27 and 30 are synchronously started from one clock generator 28. Therefore, a pulse sequence distorted by noise arrives at one input of adder 5 modulo two, and the model input directly from the output of the second pulse generator 30 is identical to the first, which allows you to compare both sequences with each other and thus evaluate the quality of the communication channel, taking into account the characteristics of signal manipulation and real interference.

The degree of mismatch is estimated by the number of mismatches of the pulses. The evaluation criterion is a change in the polarity of the pulses to the opposite or a distortion of the duration of the elementary packet by more than the duration of the clock pulse supplied to the second input of the And 6 element from the clock generator 31. In the first counter 7 of errors $, the total number of errors in each analyzed channel is calculated, which is then displayed on the indicator board 8.

A feature of the operation of the compensation unit 9 is the calculation of the correlation function of the oscillations at the output of the delay element 11, i.e. at the reference input of the quadrature filter 12, and at the output of the inverting amplifier 13. 15

Averaging is ensured by the accumulation (integration) of oscillations over a time interval longer than the duration of sending a useful signal.

In this case, the current and delayed 20 sprinkles of the useful signal are uncorrelated, and for interferences whose correlation interval is greater than the correlation interval of the useful signal, 25 estimates are generated at the output of the quadrature filter 12, which is proportional to the coefficient of correlation of oscillations at its main and reference inputs. Entering the second input of the first adder 10, the correlated interference components are read out 30. The output of the adder 10 remains a useful signal and a signal delayed by T, i.e. at the output of the adder 10, a multipath signal appears, the delayed beam of which · gg is subtracted in the adder 14. The second beam is estimated by a quadrature filter 16 from the signal delayed by T (delay element 17) and the oscillations at the output of the inverting amplifier to the correlation feedback circuit body 15 . The signal cleaned from the delayed beam from the output of the adder 14 goes to the input of the second demodulator 18. From the output of the demodulator 18, the signal 45 goes to the analysis and error counting circuit as a part of the adder 19 modulo two, element I 20, error counter 21 and indicator 22, whose work is identical to the work of similar gg elements described above.

According to the analysis results, a decision is made to transfer the radio line to a new frequency channel, in which the quality rating is the highest.

The phase shifter 29 compensates for the shift of the edges of the pulses arriving at the inputs of the adders 5 and 19 modulo two, taking into account the delay time of the useful signal in the demodulators 4 and 18. The pulse shaper 31 generates a control probe pulse of the interrogation at time points that coincide with the middle of the duration of the elementary sending of the control sequence . Such a choice of the timing of the probe pulse allows us to avoid a false quality estimate with duration distortions of less than + 40Z.

The error counters 7 and 21 received at the reference frequency generating unit 32, as well as the indicators 8 and 22 from the control and synchronization unit 33, the clock pulses set the speed and sequence of switching the local oscillator frequencies, as well as reset the error counters 7, 21 and indicator readings 8.22 after going through a measurement cycle.

Claims (2)

Claim 1. A device for evaluating the quality of a communication channel, comprising a serially connected control and synchronization unit, a reference frequency generating unit, a frequency mixer, a bandpass filter, an adder and a first demodulator, an amplitude detector connected in series to another input of the frequency mixer, an integrator and an attenuator the output of which is connected to another input of the adder, a series-connected clock, the first A pulse generator, a manipulated generator, the output of which is connected to another input of the attenuator, a phase shifter connected in series, the input of which is connected to the output of a clock generator, a pulse shaper and a first element And connected in series with the first error counter and the first indicator, the other input of which is connected to the second the output of the control and synchronization unit, the third output of which is connected to the first input of the first error counter, the second element And, the first input of which is connected to the output a clock pulse generator, a second pulse generator, the input of which is connected to the output of the phase shifter, characterized in that, in order to improve the estimation accuracy by predicting the quality of the communication channel occupied by noise, the first adder modulo two is inserted into it, connected between the output of the first demodulator and the second input of the first element AND, connected in series to the compensation unit, the second demodulator and the second adder modulo two, the output of which is connected to the second input of the second element AND, connected in series a second error counter and a second indicator, the other input of which is connected to the second output of the control and synchronization unit, the third output of which is connected to the first input of the second counter, the second input of which is connected to the output of the second AND element, while the output of the second pulse generator is connected to the second inputs the first and second adders are modulo two, the output of the first element AND is connected to the second input of the first error counter, the first input of the compensation unit is connected to the output of the adder, and the second input to the output of the attenuator . 2. The device according to p. 2, characterized in that the compensation unit contains a series-connected first adder, an inverting amplifier, a quadrature filter, the output of which is connected to the first input of the first adder, series-connected second adder, 10 an inverting amplifier and a filter, the output of which is connected to the first input of the second adder, the second input of which is connected to the output of the first adder, the first delay element, the output of which is connected to the other input of the first quadrature filter, and the input is connected to the second input of the first adder and is the first input of the compensation unit, the second element, the output of which is connected to. the input of the second quadra, and the input is the input of the unit, the output of the output of the second A 20 '' delay to another tour filter is the second compensation, the horn is an adder.