SU1363485A2 - Apparatus for statistical detection of discrete signals in communication channels with inter-symbol interference - Google Patents

Abstract

A device for the statistical detection of discrete signals in communication channels with intersymbol interference is related to telecommunications technology and can be used in monitoring and control data transmission systems. The purpose of the invention is to improve the noise immunity under the action of non-stationary interference. The goal is achieved by introducing into the device an interference analysis unit, the output of which produces an impact that controls the threshold of the decision threshold unit depending on the intensity of non-stationary interference in the communication channel, which increases the probability of a correct decision making and noise immunity of the device as a whole. 1 3. p. F-ly, 2 ill. u (L s 00 about: with Nj: СЮ Сд ю

Description

 one

The invention relates to telecommunications engineering and can be used in data transmission, monitoring and control systems.

The purpose of the invention is to improve the noise immunity of the device under the action of non-stationary interference.

Kah FIG. 1 shows the scheme of the proposed device; in fig. 2 - block diagram analysis of interference.

The device for statistical detection of discrete signals in communication channels with intersymbol interference contains receiver 1 non-original signals, block 2 delays, adder 3, decider 4, quality detector 5 shaper 6 erasure sequence, regenerator 7 T-arry signals, shaper 8 hypothetical sequence , block 9 modulo-t adders, generator 0 of estimated errors, multiplier 11 for the coefficient of noise residues, summed-up block 12, delay line 13, block 14 subtraction, multiplier 15, integrator 1 6, threshold block 17, shaper 18 hypothetical sequence, counter 19, block 20

interference analysis.

The interference analysis unit 20 comprises an amplifier 21, with adjustable gain, an amplifier 22 with constant gain, a comparator 23, a switch 24, an adder 25, 26

element

compare.

The essence of the operation of the elements contained in the interference analysis unit 20 is as follows.

The elements entered implement the learning procedure with equalized errors, which is described by the following mathematical expression:

v (n +) v (n) + .p „a (n),

y (n), y (n) where Q (n) Y (n), v4n) Y, n;

and the convergence of which to the minimum probability of error is proved.

The specified mathematical expression is implemented by the following technical devices:

V (n + l), V (n) - gain factors of the 2I amplifier with adjustable gain factor, VIB

g

0

R

0

(p) taken according to the standard scheme; characterizes the step with which this procedure is minimized to the likelihood of error and is implemented, for example, by the gain of the amplifier 22 with a constant gain set manually or automatically depending on the nature of non-stationary interference in the communication channel, moreover (n);

five

P 5

samples of channel signals, distorted interference and arriving at the output of receiver 1; threshold value com-: parator 23.

According to the indicated algorithm, depending on the level of interference in the communication channel, at the output of the interference analysis unit 20, a signal is generated, the level of which is proportional to the interference in the current channel in the channel St. -. zi This signal adjusts the threshold of decision block 4, which increases the likelihood of this block making the correct decision. Therefore, so. Since the instantaneous interference is taken into account when making a decision, then at a character-by-character reception, an ester increases the likelihood of making the right decision on the received symbol and thereby increases the noise immunity of the entire device.

The device works as follows 5 times.

The received oscillations from the output of the receiver 1 of continuous signals are fed to the inputs of the quality detector 5 and the regenerator 7 t-ary signals and Q to the input of the delay line 13. From the output of the quality detector 5, the signals are recorded in the shaper 6 of the erase sequence, and from the output of the regenerator 7 t-ary signals in the g shaper 8 of the hypothetical sequence. The write speed in the driver x 6 and 8, built on the basis of the registers of length L equal to the interval of the channel memory, is equal to

manipulation V. From the output of the imaging unit 8 1 of the hypothetical sequence, signals arrive at one group of inputs of moduli modulators 9; the speed 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 come from generator 10 alleged errors with speed VL, and the third group of inputs - signals from the output of the imaging unit 6 erase sequence. In this case, the rate of change of states at the outputs of the shaper 6 of the erase sequence depends on the number of 9 erase signals that the quality detector 5 produces, and is equal to that during the reception of one simV

at

m ox provides the output of block 9

adders modulo m forming sets of combinations of characters with allowance for assumed 1X and anomalous errors in the channel memory interval.

Each of the adders obtained at the output of block 9 according to the modulus of a combination of a set of m possible passes through the multiplier 11 to the coefficients of the noise residues determined for this channel in advance. The result of multiplying for each combination from the multiplier 11 to the noise residual coefficients is added to the summing unit 12, and then fed to the second (subtracting) input of the adder 3, to the first (summing) input of which through the block 2 delay

from the output of the receiver 1 continuous signals receives the signal of the symbol being processed. The same signal is fed to the input of the noise analysis unit 20, where it is fed to the inputs of amplifiers 21 and 22. From the output of amplifier 21 with adjustable gain, the analog signal amplified V times is fed to the input of comparator 23 where the obtained product V (n) Y is compared ( n) with a threshold P, the level of which is established when the device is tuned by inputting the device with known signals without interference and adjusting the threshold P, according to the maximum likelihood of a correct decision by decision block 4. According to the results The comparator 23 controls key 24, allowing the Pn-Y signal (n) to pass from the amplifier 22s to

This gain is either inverted or non-inverted, i.e. determines the sign of the product pn Y (n). The resulting product arrives at the second input of the adder 25, the first input of which receives the signal V (n) x Y (n) from the output of amplifier 21 with an adjustable gain factor proportional to the gain of this amplifier at the previous step. This signal and the signal from the output of the adder V (n) Y (n) + /7.Y (n) goes respectively to the first AND second

5 inputs of comparison elements 26, at the output of which a signal is formed with an increment proportional to the value of + Pp-Y (n), i.e. proportional to the change in noise at the input of the device.

0 The output signal of the comparison element 26 adjusts the gain of the amplifier 21 with an adjustable gain and adjusts the threshold of the decision block 4 to the control

5. the entrance.

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 about the transmitted symbol with

0 taking into account the intensity of the existing interference in the communication channel.

Signals from the output of the decision block

4 is fed to the input of a hypothetical sequence generator 1B for forming by acting on the information parameter of a carrier wave, similar to the hypothetical signal (t) processed by the continuous signal receiver S (t) over the channel memory length L, equal to S (t). The hypothetical signal S (t) generated by shaper 18 is fed to the second input of subtraction unit 14,

the first input of which, after the pre-delay, in the delay line 13 is the input signal S (t). The use of delay line 13 is due to the need to compensate for the time error between S (t) and

5. (t). The difference signal from the output of block 14 of the subtraction, due to both interference existing in the communication channel and erroneous decisions of the decisive block 4, is fed to both inputs

g of the multiplier 15, which performs the role of the quadrator, and then to the input of the integrator 16, where the difference energy between the signals S (t) and S (t) is calculated for the duration of L elements, where L

0

five

0

five

it is set by the capacity of the counter 19, which counts 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 the integration is fed to the threshold block 17, which has 1 thresholds. Depending on the number of erroneous decisions on the length of L elements, the magnitude of ig on the difference energy at the output of integral 15а 16 increases proportionally to the number of errors, which leads to the appearance of a component number of thresholds of 15 17 that change the threshold level 5 quality detector.

Thus, in the proposed device, noise immunity is increased by increasing the probability 20 that the decisive block 4 correctly decides when it affects the signal of transient interference, which is achieved by automatically adjusting the threshold of the decisive block 4 according to the indicated algorithm.

F o rm ula invention

the control input of the first amplifier 1. The device for the statistical about -30 l and is the output of the discrete signal analysis analysis unit in the interference channel.

lakh communication with intersymbol interference by author. St. No. 1170621, that is, to ensure that the device is not subject to noise immunity under the influence of non-stationary interference, an interference analysis unit is inserted into it, the output and input of which are connected respectively to the control input of the threshold unit and the output of the delay unit.

2. An apparatus according to claim 1, characterized in that the interference analysis unit comprises a comparison element, an adder, a comparator, a switch and amplifiers whose inputs are combined and are the input of the interference analysis unit, the output of the first amplifier is connected to the comparator input and first the input of the adder and the reference element, the output of the second amplifier is connected to the first input of the key, the second input of which is connected to the comparator output, the output of the key is connected to the second input of the adder, the output of which is connected to the second input of the comparison element, the output of which is connected en to

lakh communication with intersymbol interference by aut. St. No. 1170621, which is based on the fact that, in order to increase the noise immunity of the device under the action of non-stationary interference, an interference analysis block was inserted into it, the output and input of which are connected respectively to the control input of the threshold block and the output of the delay block.

2. The device according to claim 1, characterized in that the interference analysis unit comprises a comparison element, an adder, a comparator, a switch and amplifiers whose inputs are combined and are the input of the interference analysis unit, the output of the first amplifier is connected to the comparator input and the first input of the adder and the comparison element, the output of the second amplifier is connected to the first key input, the second input of which is connected to the comparator output, the key output is connected to the second input of the adder, the output of which is connected to the second input of the comparison element, the output of which is connected en k

Compiled by S. Berestevich. Editor T. Lazorenko Tehred L. Serdyukova Proofreader S. Shekmar

Order 6380/54

Circulation 900 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

FIG. 2

Claims (2)

Claim 1. A device for the statistical detection of discrete signals 06-3Q in communication channels with intersymbol interference according to ed. St. No. 117062.1, which entails that, in order to increase the noise immunity of the device under the influence of non-stationary interference, a noise analysis block is introduced into it, the output and input of which are connected respectively to the control input of the threshold block and the output of the delay block. 2. The device pop. 1, characterized in that the interference analysis unit contains a comparison element, an adder, a comparator, a key and amplifiers, the inputs of which are combined and are the input of an interference analysis unit, the output of the first amplifier is connected to the comparator input and the first input of the adder and the comparison element, the output of the second amplifier connected to the first input of the key, the second input of which is connected to the output of the comparator, the output of the key is connected to the second input of the adder, the output of which is connected to the second input of the comparison element, the output of which is connected to the control input of the first amplifier and the output is a noise analysis unit. Fig.X FIG. 2