SU1334381A1 - Device for checking signal-noise ratio - Google Patents

Abstract

The invention relates to telecommunications and provides increased control accuracy in communication channels with noise-like signals. The device contains demodulator 1, quadrants 11, 15, 16, averaging blocks 12, 14, 17, subtraction blocks 18, 20, dividers 21 and 23. Averaged blobk 9, quad 10, subtractors 13 and 19, again, switch Yel 22. Demodulator 1 contains correlators 2 and 8, shift register 3 rr 4 reference signal, discriminator 5, clock Fp 6, adder 7. 1 Cp , 2 Il. from from 4 to 00 flove. /

Description

The invention relates to telecommunications and can be used to assess the quality of transmission of noise-like signals (PSS) over communication lines and to assess the performance of PSS receivers.

The purpose of the invention is to improve the accuracy of monitoring in communication channels with noise-like signals.

FIG. Figure 1 shows the structure of the electrical circuit of the device for controlling the signal-to-noise ratio; Fig. 2 shows the mutual correlation functions of the received and reference signals of the demodulator, which explain the operation of the device.

The device for controlling the signal-to-noise ratio contains a demodulator 1 containing the first correlator 2, the shift register 3, the generator 4 of the reference signal 5 the discriminator 5, the clock generator 6, the adder 7 and the second correlator 8, the third averaging unit 9, the third quad 10, the fourth quad 11, the fourth averaging block 12, the second subtracting block 13, the first averaging block 14, the first quad 15, the second quad 16, the second averaging block 17, the first subtracting block 18, the third subtracting block 19, the fourth subtracting block 20, the second divider 21, switch 22, p rvy divider 23.

The device works as follows.

The input of the entire device is, p input demodulator a 1. The device receives a mixture U (t) of a noise-like signal S (t), for example, M of a sequence with amplitude A and Random delay T, and noise (t) with dispersion a, and fed to correlator 2 and discriminator 5 " The reference signal generator 4 forms at its output a copy of the transmitted signal S (t) o The back signal is fed to a register, 3 shifts, on the three outputs of which the copies S (t), S (t) and S (t) of the reference signal are formed, differing offset in time by one cycle (for the duration of the elementary cTj,). The reference signal of the correlator 2 is the signal S (t), taken from the second output of register 3, and the reference signals of the discriminator 5 are the delayed and leading signals S .-, (t) and) taken from the third and first outputs

register 3. Correlator 2 at its output generates a signal V, convolutions U (t) and S (t), and discriminator 5 generates at its output a signal El synchronization error, r Proportional convolution U (t) and the difference signal S (t) - S (t), - An error signal from the output of the discriminator 5 is supplied to

clock generator 6. The clock generator 6 generates at its output clock pulses (the frequency of which depends on the control signal), which determine the frequency of the elementary dressing of the generator 4 of the reference signal. Blocks 3-6 form a known circuit for monitoring the delay of noise-like signals.

In the absence of interference and fluctuations

 the delay of the received signal the signal-to-noise ratio for the power at the output of the correlator 2 is

0

Bh

6x

 in .0

where h

6x

signal-to-noise ratio at the input of the correlator; B is the base of the sigtal, with the signal power of the correlator 2

output equals

H

35

noise dispersion

all the way

in the state of tracking the delay of the received signal, the delay of the reference signal S (t) fluctuates around the peak of the mutual correlation function of the reference signal and the received signal, while the output signal level starts, which leads to a decrease in the average power of the useful signal by some amount (uA) :

A2 A (o

- (uA)

By this, the noise variance is increased by a certain amount (uG):

)

The known signal / noise signal control devices measure the ratio of A. and G, and not A

about

determining the levels of signal and noise in the channel, which reduces the accuracy of measurements. Known devices, moreover, do not control signal loss.

- 1334381

(uA) and noise increase (lb), St. - Loss of the signal and increase with the operation of the noise behind the delayed-Persian output of the correlator 8,

of the demodulator system 1. It is unassociated with the delay fluctuations T,

allows you to control the operation of the magnet.

This system, for example, when optimizing the Signal V, from the output of the first correction of its minimum operation (dA) or torus 2 enters block 9 averaging (SL-C) .ni and quad 10. At the output of the block

The reference signal of the second correl-9 forms the value of M, is equal to

Torus 8 is the sum of the reference signals — a 10-mean value (mathematical

catch S (t), S (t) and S (t), formed by waiting) V, adder 7.

Type of mutual correlation functions V A

of the received and reference signals showing the dependence of the output signals. At the output of the quadrant 11, the signals of the correlators 2, 8 and the discriminative signal L ,, equal to the square V, of the regulator 5 from the detuning T are given on

FIG. 2. The correlation function of noise is L, V.

similar signals has a triangular

a form with a base equal to dpitel- 20 From the output of block 9, averaging the sign of two elementary parcels (2T), is fed into the quadrant of GO, on you, which are shifted in time during the inter-course of which the value of the shaft TO is formed is the reference signals S (t ), S (t) and

S. (t) (Fig. 2a, b, c) have corresponding -No (V),

time-shifted major

petals of mutual correlation with the signal from the signal of the function E (y), () understood by the signal from the signal of the quadrant 11, go to averaging block 12, to the output and to E (t). The dependence of the level of the course of which is formed by the magnitude of the second signal at the output of the correlator 2

from temporary detuning shows 30 L, V A + a. curve E (o). Discriminatory characteristic of the discriminator 5 forms-. At the output of block 13, the value of the noise variance is subtracted by the subtracting (c) and E (C) (Fig. 2d). Mutual correlation function Е С) of the received signal from 35 С L, - К. the sum of the reference, offset relative to each other signals, has a flat blocks 14-18 work similarly

a vertex (Fig. 2d), it is formed by sum-blocks 9-13.

world, E (s), E (t-) and E (tr), with the output of the quad 15 of this section of uk, corresponding to 40, the value of A is formed, is equal to the square of the working area de discriminatory-average of the output signal characteristics E, (T), the level of the correlator of the correlator 8, and the output of the signal block does not depend on the delay-18 subtraction; - g correlator of torus 8. From the output of block 18 of the signal at the output of the correlator of torus 2 at C, the cash is fed to divider 21, 0. suschest- noise variance for G vyhodevl yuschy SGI values division by three, the correlator 8 at three times the dis-wherein the output of the divider 21 for the formation of noise persia vkode correlator 2 ruets Majestic | 1a G o. Signals A, and A, in the absence of fluctuations of the delay gQ, arrive at block 20, on a, because the noise component (t), the output of which is formed, multiplies in the correlator 8c ortho. S (t), S (t) and (lА) А - А with the peronal signals. S (t) forms three orthogonal noise components, each of which has gg. Signals C and GO enter the dispersion block G with the resulting dis-19 subtraction, at the output of which the value is generated

sixteen)

5 13

The signal A2 is fed to a divider 23, to the second input of which, depending on the position of the switch 22, the dispersion value O (position from the switch), the value (lA) (position b) or the value (lS3) (position a). At the same time, in position c, at the output of dehgitel 23, the signal-to-noise ratio is formed; in position b, the value (LA), which characterizes the ratio of signal power to signal power loss associated with the action of the tracking system of demodulator 1, A is the value of A | / (yb), characterizing the ratio of the signal power to the variance of the additive noise associated with the action of the demodulator tracking system.

Claims (2)

1. A device for controlling the signal-to-noise ratio, containing a demodulator, connected in series the first averaging unit and the first quadrant, the output of which is connected to the first inputs of the first divider and the first block. The readout is connected in series to the second quadrant, the input of which is connected to the input of the first block averaging, and the second unit of the uS unit, the output of which is connected to the second input of the subtraction unit, is due to the fact that, in order to increase the control accuracy in communication channels with noise-like: and signals, consequently, the third averaging unit is connected, the third quadrantor is the second subtraction unit, the third subtraction unit and the switch, the output of which is connected to the second input of the first divider, then the fourth quadrant and fourth averaging unit, the output of which is connected to the second input of the second subtraction unit, the fourth subtraction unit connected between the output of the third quadrant and the second input of the switch, the second divider, the input of which is connected to the output of the first subtraction unit, and the output connected to the second input of the third subtraction unit and to the third input of the switch, while the second input of the fourth subtraction unit is connected to the output of the first quad, the first output of the demodulator is connected to the input am of the third averaging unit and the fourth quadrant, and the second output is connected to the input of the first averaging unit .. 2. Device POP.1, characterized in that the demodulator contains serially connected shift register, discriminator, clock generator and generator of the reference signal, the output of which is connected to the input of the shift register., The first correlator, the first input of which is connected to the first input of the second correl and a second discriminator input and is the demodulator input, and an adder, the output of which is connected to the second input of the second correlator, the output of which is the second output of the demodulator, the first output of the shift register The key to the first input of the adder, the second output of the shift register is connected to the second inputs of the first correlator and the adder, a third shift register output is connected to the third input of the discriminator and the adder, and the output of the first correlator is the first output of demodulator d  2Zo -Go OT Te 2Tv FIG. 2