SU1587659A1 - Demodulator of signals of multiplexing phase manipulation - Google Patents

Abstract

The invention relates to communication systems and can be used to receive discrete information in systems with phase modulation methods. The aim of the invention is to improve noise immunity. For this, an amplitude detector 13 is inserted into the demodulator, and the source of the initial setup 5 and the switch 3 is inserted into each channel. The absolute initial phase of the reference oscillation is distinguished on all parts of the packet, which makes it possible to use absolute phase shift control. 3 il.

Description

f

(21) kk777 7 / 2k-OS

(22) 08/17/88

(tt6) 08/23/90. Bul N- 31

(71) Leningrad Electrotechnical Institute of Communications. prof. M.L.Bonch-Bruevich

(72) G.V.Antonov and I.V. Gurevich (53) 621.39.62 (088.8)

I

(56) Author's sviletedelstvo USSR

No. 1515388. class. H Oi L 27/22, 1987.

(W) DEMODULATOR SIGNALS OF MULTIPLE PHASE MANIPULATION

(57) The invention relates to communication systems and can be used to receive discrete information in systems with phase modulation methods. The aim of the invention is to enhance noise immunity. For this, an amplitude detector 13 is introduced into the demodulator, and the source of the initial setting 5 and the switch 3 is inserted into each channel. An absolute initial phase of the reference oscillation is allocated to all sections of the packet, which makes it possible to use absolute phase shift manipulation. 3 il. .

(L

with

SP

00

ABOUT)

ate

31587659

refers to systems

ns h

communication and can be used to receive discrete information in systems with phase modulation methods.

The aim of the invention is to improve noise immunity.

Fig. 1 shows a structural-electrical circuit of the demodulator; in fig. 2 - vector diagrams; in fig. 3 - stress plots showing his work.

The demodulator contains in each channel a phase detector 1, a comparator 2, a switch 3, a multiplier 4 and a source 5 of the initial setup signal, as well as signal phasers 6, an adder 7, a filter 8, reference oscillation phasers 9, a clock frequency selector 10, a decisive unit 11 , block 12 delay and amplitude detector 13.

The demodulator works as follows.

For the description of the operation of the demodulator, consider FIG. 2, in which the first to N 2 signal variants are shown in solid lines, and the reference oscillations are shown in dotted lines. For simplicity, FIG. 2 shows a diagram for N 2 8.

In the steady state, when reference oscillations are applied to the second inputs of the phase detectors 1, in accordance with FIG. 2, the following relationships occur.

 Denote by S; (t) the signal variant.

Sj (t) acos (Ot iuCf)

i (O, N-1), ul

(one)

where a and 00 are the amplitude and frequency of the signal, respectively, and the reference oscillation applied to the second input of the corresponding phase detector 1 is denoted by Uj (t)

U: (t) Ucos (COt - -

U (-P

+ j

-d

- 12

(2)

where and is the amplitude of the reference oscillation, without loss of generality, we will consider it as a unit.

At the outputs of phase detectors 1, the projections of the received CI-lines onto the coordinate axes corresponding to the reference oscillations are calculated. We denote these projections by SYMBOL C ,,, where

 J 1 refers to the signal number, and

to the number of porous fluctuations

signC, j acos (i + j) uqi J II uq 1 -2- -T-J (3)

five

0

five

0

At the outputs of the comparators 2, the signs of projections are formed. Through the switch 3, these signs arrive at the second inputs of the multipliers k, the first inputs of which receive the phase-shifted input signals. The results of the multiplication are summed in adder 7 and filtered by filter 8. At the output of filter 8, a distinguished reference oscillation U (t) takes place:

VN / 2g-.chg,

and (t) Z: cosfcOt - i Jt-llil .0 L

one

N

ysignC ;:

 N

cos C3t +

i (0. N - 1)

11 1

T tTj; W

0

five

0

five

The selected reference oscillation through the phase shifters of the reference oscillation 9 is fed to the second inputs of the phase 5 detectors T, the output of which forms projections in accordance with (3).

Relation (4) has a place in steady state. In the process of establishing this ratio. . . it may not be executed, this is due to the fact that at the initial moment the signs at the outputs of the comparators 2 are of a 1 + ay character, since the reference oscillation is not yet distinguished.

Depending on the initial state of the comparators 2 and the incoming signal, the selected reference oscillation and (t) may have a phase that is different

on C)

Consider FIG. For, which shows a temporary diagram of the si-nal in batch mode. Plot I is the preamble on which the unmanipulated carrier is transmitted, in Plot 2 information is transmitted, 3 is the moments of manipulation, k is the pause between packets.

The reference oscillation at the output of the filter 8 increases gradually, the growth rate is determined mainly by the band of this filter 8.

In the pauses (section k), the signal is absent and the reference oscillation is also absent, in this case the voltage at the output of the amplitude detector 13 is zero and the switches 3 connect the sources of the initial setting signal to the second input of the multipliers k.

Let us denote by E the voltage at the output of comparator 2, corresponding to a logical zero, and the symbol to a logical one. In this case, the voltage source of the initial installation signal E is

15

° 1

 ° J

 FsignC-jj,

however, the initial phase of the preamble is considered to be zero. Since the signs at the outputs of the switches 3 correspond to FIG. 2, the output of the filter 8 has a growth of the reference oscillation, the amplitude detector 13 selects the envelope of the reference oscillation a (t), B the time tg when the value of a (t) becomes greater than the trigger threshold of the switch a, the switches 3 are connected to the second input of multipliers 4, the outputs of the comparators 2, while at the output of the phase detectors 1, the values of the projections correspond to FIG. 2, and there is an established process on that-package layer, where information is transmitted (sections 2). During the pause between the packets (part k), there is no signal and the amplitude of the reference oscillation at the output of the filter 8 decreases, at the moment 1

 6B1 CL

when the voltage at the output of the amplitude detector 13 is less than a „, the switches 3 will again connect to the second inputs;} multipliers 4 sources 5 of the initial setup signal. The process then repeats. Thus, an absolute initial phase of the reference oscillation is separated on all parts of the packet, which makes it possible to use absolute phase shift keying.

The trigger threshold of the switch should be selected so that

- the end of the preamble, - you (; l in a pause (fig. Зб).

Claims (1)

5 claims e 10 15 20 25 A multi-phase-shift keying demodulator containing a clock extractor, a deciding unit, a delay unit, serially connected reference oscillators, serially connected signal phasers, serially connected adder and filter, and in each channel a multiplier and serially connected phase detector and comparator, the outputs of the phase detectors of all channels are connected to the information inputs of the decision block, the clock input of which is connected to the output The clock frequency separator, the multiplier outputs of all channels are connected to the inputs of the adder, the filter output is connected to the input of the first phase shifter of the reference oscillation, the output of which, as well as the outputs of the remaining phase shifters of the reference oscillation are connected to the first inputs of the phase detectors of the corresponding channels, the output of the delay generator. to the first input of the multiplier of the last channel and the input of the first signal phasers, the output of which and the outputs of the remaining signal phasers are connected to the first inputs of the multipliers the corresponding channels, the clock selector inputs, the delay block and the second inputs of the phase detectors are combined and are the input of a demodulator, the outputs of which are the outputs of the decision block, characterized in that, in order to improve the noise immunity, an amplitude detector is inserted, and each channel - serially connected signal source of the initial installation and a switch, the output and the second input of which are connected respectively to the second input of the multiplier and the output of the comparator, the output of the filter is connected to the input of am litudnogo detector, whose output is connected to the third input switches all channels. 35 40 45 50 but sit) 3 3 d 3