SU1170621A2 - Device for statistical detecting of digital signals in communication channels with intersymbol interference - Google Patents

Abstract

DEVICE FOR STATISTICAL DETECTION OF DISCRETE SIGNALS IN THE COMMUNICATION CHANNELS WITH INTERSYMBOL INTERFERENCE ON AUT.SV. No. 754687, differing from the fact that, in order to improve noise immunity in communication channels with variable parameters, serially connected delay lines, a subtraction unit, a multiplier, an integrator and a threshold block, as well as an additional hypothetical sequence generator and counter, to the input of which and the output of the decision block is connected to the first input of the hypothetical sequence former; an additional you is connected to the second input of the additional form of the hypothetical sequence The receiver of continuous signals, the output of which is connected to the input of the delay line, while the output of the additional generator of the hypothetical sequence is connected to the second input of the subtractor, the output of the latter is connected to the second input (L of the multiplier, and the outputs of the counter and threshold block are connected to the control inputs respectively of the integrator and a quality detector.

Description

a 1C

The invention relates to the use of the ELECTRONIC TECHNIQUE in the data transmission system of the monitoring control 11, which is the perfection of the invention described in the author. No. 754687,

The purpose of the invention is to increase the noise immunity in communication channels with common parameters.

The drawing shows a structural electrical circuit of the device.

A device for the statistical detection of discrete signals in communication channels with intersymbol interference contains a receiver 1 of continuous signals, a block 2 of delay, an adder 3, a decisive block 4, a quality detector 5, an erasure generator 6

regenerator 7t-ary signals, driver O

8 hypothetical sequence, block of adders 9 modulo m, generator 10 of supposed errors, (Multiplier 11 on noise residual coefficients, summing block 12, delay linsho 13, block 14 subtractive subtractor 15, integrator 16, threshold-block 17, additional driver 18 hypothetical sequence counter 19.

The device for statistical detection of discrete signals in communication channels with intersymbol interference works as follows.

Acceptance of oscillations from the output of the reception of NS1 of continuous signals is fed to the inputs of the quality detector 5 and the regenerator 7t of the primary signals and to the input of the delay line 13. From the output of the quality detector 5, the signals are written, ashts to the erasure generator 6, and from the output of the regenerator 7 GP -ary signals - in the imaging unit 8 hypothetical sequence. The write speed in shaper 6 and 8, built on the basis of the shift registers of length .1) equal to the channel memory interval, is equal to the manipulation speed Y. From the output of the imaging unit 8 of the hypothetical sequence, signals arrive at one group of inputs of block 9 adders modulo m, while the rate of change of states at the outputs of the imaging unit 8 of the hypothetical sequence is always V, to another group of inputs of which signals are received from the generator 10 VL, and the third group of inputs receives signals from the output of the imaging unit 6 erase sequence. With

This rate of change of states at the outputs of the imaging unit 6 of the erase sequence depends on the number 0 of erase signals, which the quality detector 5 has, and is equal to

Vm, that aa time of reception of one character provides at the output of block 9 adders modulo pz the formation of sets of combinations of characters taking into account the expected and anamalous errors

on the channel memory interval.

Each combination obtained from the output of block 9 modulators w from a set of m possible passes through a multiplier 11 in advance for a given channel. The result of multiplying for each combination from the output of the multiplex {itel 11 to the noise residual coefficients is added to the summing block 12, and then fed to the second (subtracting) input of the adder 3, to the first (summing) input through the block 2 delays from the output of the receiver 1 continuous signals signal being processed character.

The signal from the output of the adder 3 is analyzed in decision block 4 on the memory interval of the channel L and then a decision is made on the transmitted symbol.

The number of erase signals depends on the threshold level set in the detector 5 quality and quality of the communication channel. When the quality of the communication channel deteriorates, the probability of an undetected error of the quality detector 5 increases if the threshold level of the quality detector 5 is left unchanged, which leads to a decrease in noise immunity, reception. To eliminate this effect, it is necessary to change the threshold level of the quality detector 5. It happens as follows.

The signals from the output of the decision block 4 are fed to the input of the additional generator 18 of the hypothetical sequence to form by affecting the information parameter of the carrier wave, similar to the noise signal residuals processed by the receiver 5 (i) of the hypothetical noise residues, determined by

signal 5 (t) on the memory length of channel 1, equal to 5 (i), the hypothetical signal formed by the additional generator 18 (i) is fed to the second input of the subtraction unit 14, to the first input of which, after a preliminary delay, the input signal 5 (i). The use of delay line 13 is due to the need to compensate for the time error between 5 (i) ib (). The difference signal from the output of subtraction unit 14, due both to interference on this communication channel and erroneous decisions of solving unit 4, goes to both inputs of the multiplier 15, which plays the role of a quad, and then to the input of the integrator 16, where energy is calculated the differences between the signals 5 (i) and 5 (i) over the duration of L elements, where L is determined by the capacity of the counter 19,

14

counting the current number of decisions, and the recalculation signals serve as the clock signals of the integrator 16, which determine the running time.

The result of integration is fed to the Threshold block 17, which has B time, Depending on the number of erroneous decisions on the length of L elements, the magnitude of the difference energy at the output

the integrator 16 grows in proportion to the number of errors, which leads to the appearance of the corresponding number of poros1 s at the output of the threshold block 17, which change the threshold level of the quality detector 5.

Thus, the proposed device allows to increase the noise immunity in the channels with variable (Parameters by changing the level of the quality detector threshold depending on the quality of the communication channel.

Claims (1)

DEVICE FOR STATISTICAL DETECTION OF DISCRETE SIGNALS IN CHANNELS FOR COMMUNICATION WITH INTER-CHARACTER INTERFERENCE by ed. No. 754687, characterized in that, in order to increase the noise immunity in communication channels with variable parameters, a delay line, a subtraction block, a multiplier, an integrator and a threshold 'block are introduced in series, as well as an additional hypothetical sequence generator and counter, to the input of which the output of the decider block is connected to the first input of the hypothetical sequence former, the additional output is connected to the second input of the additional hypothetical sequence former a continuous signal generator whose output is connected to the input of the delay line, while the output of the additional hypothetical sequence generator is connected to the second input of the subtraction unit, the output of the last g is connected to the second input of the multiplier, and the outputs of the counter and threshold block are connected to the control inputs of the integrator and quality detector. SU „„ 1170621