SU1540030A1 - Adaptive receiver of signals with pzase-difference modulation - Google Patents

Abstract

The invention relates to telecommunications. The purpose of the invention is to improve noise immunity. The adaptive receiver contains multipliers 1, 2, 9 and 10, delay line 3, phase shifter 4, integrators 5 and 6, memory blocks 7 and 8, adders 11 and 12, threshold unit 13, and decisive unit 14. The goal is achieved by providing a choice of minimizing the likelihood of error receiving signals with phase difference modulation of the first or second order. 1 il.

Description

12

13

CI

G

If

YU

I

g

Output

SP

4b

with

The invention relates to telecommunications and can be used in signal transmission systems with phase difference modulation.

The purpose of the invention is to improve the noise immunity by selecting at the minimum the probability of error in receiving signals with phase difference modulation of the first or second order.

The drawing shows a structural electrical circuit of the proposed receiver.

The adaptive receiver of signals with phase difference modulation contains per- | rg of the same amplitude, but counter 1 and second 2 multipliers, delay line 3, phase shifter 4, first 5 and second 6 integrators, first 7 and second 8 memory blocks, third 9 and the fourth 10 multipliers, the first 11 and second 12 adders, the threshold unit 13 and the decision unit 14.

Adaptive receiver works as follows.

Let its input be a signal x (t) asin (tu0t + cf), consisting of n consecutive arrivals, where n is an integer, a is the signal amplitude, W0 is the signal frequency, if is the signal phase.

Consider the three premises:

20

25

thirty

signal, but there is no signal at its output.

The threshold unit 13 triggers and the decision block 14 connects to its output a signal from the output of the integrator 5, i.e. in the case of the absence of non-additive interference, the receiver is selected with the PRM-1.

If a non-additive interference appears on the communication channel, the signal at the input of the adaptive receiver is:

x „, (t) asin (we + # t + ifn (,

(n-l) T t 4nT,

x n (t) asin (co0 + i) t + cn nT t (n + l) T,

, (t) asin (wct,),

(n-l) T t inT;

aain (to0t

+ 4 ,.

xh (t)

nT t Ј (n + l) T, HG1 +, With asin (w0t + 4V,), (n + l) (n + 2) T,

where, tfn,

if, - phase (n-1), n, (n + l), the signal sendings, respectively, j T - the duration of the package

signal.

Let the phase difference between the nth and (n-1) -th premises be equal to the phase difference between the (n + 1) -th and nth premises and be FH, i.e.

Mp

(W.-Fm) (v “. Then, at the output of the adder 11, the sinal is proportional to the cosine of the second

phase difference (t / n- М ,,.,) (V -) in О and is equal to

a t

a4 T

Uafx (t) j - -jcos 0-,

304

where (t) J is the output voltage

adder 1 1.

At the output of the integrator 5, the signal is proportional to the cosine of the first phase difference (W n MV-,) and is equal to

0,

cos

-A5T

where ig tx (t) is the output voltage

integrator 5.

Thus, the inputs of the additional adder 12 receive two

signal, but there is no signal at its output.

The threshold unit 13 triggers and the decision block 14 connects to its output a signal from the output of the integrator 5, i.e. in the case of the absence of non-additive interference, the receiver is selected with the PRM-1.

If a non-additive interference appears on the communication channel, the signal at the input of the adaptive receiver is:

x „, (t) asin (we + # t + ifn (,

(n-l) T t 4nT,

x n (t) asin (co0 + i) t + cn nT t (n + l) T,

x n + 1 (t) asin (s „+ J) t + tfn +, t (n + l) T t 4 (n + 2) T,

but at the output of the adder Il remains unchanged, since P (PRK-2) is in var,

40

45

50

55

At the same time, the signal at the output of the integrator 5 is proportional to cos (tfn-H n-1 + H) where the delay time of the signal in the delay line 3, which is chosen from the condition t T

In this connection, the difference signal at the output of the adder I2 is different from zero, and if the threshold value is exceeded, the threshold unit 13 is triggered and the decision block 14 connects the output signal from the output of the adder 11 of the receiver with PRM-2 to its output.

Thus, when the level of nonadditive interference exceeds the threshold, a receiver with PRM-2 is selected.

The threshold level of interference (nof) is selected from the conditions

r-wu «wosh

(FRM-2) 7

where Rv "(FRM-1),

POU (FRM-2) - error probability

signal reception in premix with FRM-1 and FRM-2, respectively,

those. The threshold level of nonadditive interference is selected from the condition that the likelihood of signal reception errors in receivers with FRM-1 and FRM-2 is equal.

t

Thus, the proposed adaptive receiver of signals with phase difference modulation possesses the best noise immunity indicators as compared to each of the receivers with the first and second order differential difference modulation, taken separately, since both of these receivers , it optimally (in terms of the minimum probability of signal reception errors) selects a receiver with PRM-1 or RPM-2.

Claims (1)

Invention Formula An adaptive receiver of signals with phase-difference modulation, containing the first and second multipliers, the first inputs of which are connected to the input of the delay line, the output of which is connected to the input of the phase shifter, and to the second input of the first multiplier, the output of which through the first integrator is connected to the first input of the third multiplier and to the input of the first memory block, the output of which is connected to the second input of the third multiplier, the output of which is connected to the first input of the first adder fan, the second input of which is connected to the output of the fourth multiplier, the second input which is connected to the output of the second memory block, the input of which is connected to the first input of the fourth multiplier and to the output of this integrator, the input of which is connected to the output of the second multiplier , the second input of which is connected to the output of the phase shifter, about t and h with the fact that, in order to increase noise immunity by selecting the minimum likelihood of receiving errors of signals with phase difference modulation of the first or second order, A decision block, a threshold block and a second adder, the output of which is connected to the input of the threshold block, the output of which is connected to the first input of the decision block, the second input of which is connected to the output of the first integrator and the first input of the second adder, the second input of which with the output of the first adder to a third input of s casting unit,