SU1019662A1 - Demodulator of multichannel modem with amplitude-phase difference modulation - Google Patents

Abstract

; DEMO KNOWLEDGE .lami tee - with BTopbtM, a. the average output of the middle with the nepstm input of the armature coupler and with its voltage through the Shaper iiioporoBPro voltage, as well as the connected coupled driver reH i iiTOp; frequency synthesizer and oscillator, 6 t if h tp w and so that; in order to increase the noise level. receiving, introduced in series the additional subtraction unit, the average controller, 6L | 01C coded. ny and additional multiplier, the first input of the additional bypassing block i of the reading block is connected to aMnJStTyA output of the calculating block; BTO-V pry input with reference voltage source, switch output doe-,. | | Dinen with another input is optional; multiplier; its output is: Soeg Yeshnen with another input pemgoshtel. NMR f f sh ts9 5.

Description

The invention relates to communication technology. A multichannel modem demodulator with amplitude-phase difference manipulation is known, containing serially connected analog digital converter, multiplier, integrator, key and Olok computation, the phase output of which is connected to the first input of the computation unit and through the memory unit to its second input , and the amplitude output is connected to the first input of the comparator and to its second input through the threshold voltage generator, as well as the master oscillator, frequency synthesizer and switchboard connected in series. However, in a known demodulator, the reception noise immunity is insufficient. The purpose of the invention is to improve the noise immunity of reception. The goal is achieved by the fact that a multi-channel demodulator could have it with amplitude-phase-difference manipulation, containing successively connected analog-digital converter, multiplier, integrator, key and calculator, the phase output of which is connected to the first input of the subtraction unit and through the memory unit is with its second input, and the amplitude output is connected to the first input of the comparator and to its second input through a threshold voltage generator, as well as a series-connected master oscillator, synthesis the frequency torus and the switch are connected in series with an additional subtraction unit, averager, coding unit and optional multiplier, the first input of the additional subtraction unit connected to the amplitude output of the output unit, the second input to the source of its voltage supports, the output of the switch connected to another input additional multiplier, the output of which is connected to another input of the multiplier. The drawing shows a structural electrical circuit of the proposed demodulator. The demodulator contains an analog-digital converter 1, an intermixer 2, an integrator 3, a key 4, a calculation block 5, a subtraction block 6, a memory block 7. The comparator B, the threshold voltage generator 9, the frequency synthesizer 10, the master oscillator 11j switch 12, the unit 13 is the subtractor, the averager 14, the unit 15 is encoded, the multiplier 16. The demodulator works in a manner. The group signal at the demodulator output of the multichannel modem is the sum of the channel signals, the amplitudes of which are distorted by the influence of the non-uniformity of the amplitude-frequency characteristic (AFC) of the communication channel. In the analog-digital converter 1, the instantaneous values of the input signal level S (t) are encoded into digital sequences. These sequences are then fed to the first input of the (main) multiplier 2, in which each of the instantaneous values of the input signal voltage in digital form is multiplied by digital samples of the mutually orthogonal oscillations of each of the channel reference frequencies S 21 W t and C05 2 It fjt, 10 frequencies produced in the synthesizer at time t-. In the integrator 3, the results of the multiplications produced during the time of the divergence T are added. These sums are called the projections of the input signal to the coordinate functions 51 and 2Tf j t and X.rsCt /). j X $ {iOcos27rf.t. After the orthogonality time T, key 4 will open and the projection values of the input signal xy, will be taken from the output of the integrator 3 and through the key 4 will go to the input of the calculation unit 5. In it, by the projection xj, y is determined by the 1mplitude of the input channel signal for each premise using the formula t - in the comparator 8, the calculated value is compared with the reference voltage produced by the threshold voltage 9 for example, and the result of the comparison is O or Ch. For the detection of phase cracks, the edges of the indicated nodes, subtraction block 6 and memory block 7 are also used, which realize the correlation reception method. At the end of the orthogonality interval T, the phase output of the calculating unit 5 in digital form is fed to the analog phase of the channel signal calculated by the formula e - aiCtgVi / Xi. In subtraction block 6, this value is subtracted from the value of the phase of the channel signal on the previous parcel, stored in block 7 and amp; ,,

and converting phase differences to information symbols.

In order to improve the reception noise immunity, the calculated values

the amplitudes of the channel signals RJ are fed to the first input of the additional subtraction unit 13, which calculates the difference between the threshold voltage Ufljjp, entered into the second

. Its input, and size RJ;

j Unop-Rj.

The calculated differences, are averaged over a large time interval of several tens of bUjj, p g unj (t) dt. Coding unit 15 converts the quantities arriving at its input to channel correction coefficients KJ applied to the input of the (additional) multiplier 16, which can be switched on, or between the output of the analog-to-digital converter and the first input of the main multiplier. Thus, each of the channel reference frequencies will be multiplied by its correction factor K i and its level at the input of the main multiplier will vary in proportion to the attenuation obtained by the corresponding channel frequency in the communication channel. At the output of the (main) multiplier 2, the multiplication results will be corrected by correction factors and now

x - K.Z5 (Wsin2rf.,

J L / HX. “T.

| y --Kj-T5 (t,) cos235 j-t, -;

Consequently, the c1 amplitudes of the input channel signals will be corrected and will be equal to

a

.

As a result of such a correction, the noise immunity of the demodulator reception will significantly increase.

five

The feasibility of using the proposed device is as follows.

The proposed demodulator, due to the introduction of new nodes, ensures a higher noise immunity of the demodulation of receiving Fx signals, while not degrading: none of the main parameters of the demodulator. Advantages of demodul torus

5 to add also that its setting is maintained automatically. to the working signal and, therefore, no additional reverse channel is required for the transfer of control signals

0 laziness and additional settings vrshm unlike the well-known denode tor.

Claims (1)

A MULTI-CHANNEL MODEM DEMODULATOR WITH AMPLITUDE-PHASE-DIFFERENTIAL MANIPULATION, containing a series-connected analog-to-digital converter, a multiplier, an integrator, a key and a calculation unit, the phase output of which is connected to the first input of the subtraction unit and through the memory unit to the second input, and with the first input of the comparator and with its second * input through the threshold voltage generator, as well as serially connected master oscillator, frequency synthesizer and commutator, excellent then, in order to increase the noise immunity of the reception, an additional subtraction unit, a co-amplifier, a coding unit, and an additional multiplier are introduced in series, the first input of an additional subtraction unit connected to the amplitude output of the calculation unit, then *, swarm input - with a reference source | voltage, the output of the switch is connected to another input of the additional-I, the first switch, the output of which is connected to the other input of the switch. 1