SU1392629A1 - Digital signal receiver - Google Patents

Abstract

The invention relates to telecommunications. The purpose of the invention is to improve noise immunity. The device contains an error calculation block 1, an AGC amplifier 2, a phase shifter 3, an ADC 4, an adaptive equalizer 5, a demultiplication and phase compensation block 7, a block 8, a decoder 9, a level adjustment block 6 is inserted adders and four multipliers. The amplifier 2 performs AGC based on the average signal power. However, this adjustment does not provide accurate level tracking, since The average power of the input signal ambiguously determines the nominal level of the signal at the output of block 7. Phaser 3 is a Hilbert converter and serves to generate two orthogonal signals (subchannels R and Q). The signal from AHJI4 is fed to the equalizer 5, in which the intersymbol interference is corrected. The corrected signal arrives at block 6, which performs fine adjustment of the signal level. In block 7, the disturbance of the carrier oscillation is determined by forming the coordinate axes in accordance with the received signal. 2 Il. with (L

Description

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CO CO 1chE Ot) KD CO

The invention relates to telecommunications and other areas associated with the reception of data signals transmitted over communication channels.

The purpose of the invention is to improve noise immunity.

FIG. depicts a structural electrical circuit of the proposed device; FIG. 2 shows a structural electric circuit of a level adjustment block “

The digital device for receiving signals contains an error calculator, an amplifier 2 with automatic gain control (AGC), a phase shifter 3, an analog-digital converter A, an adaptive equalizer 5, an ultrasonic adjustment unit 6, a phase demodulation and phase compensation unit 7, a decisive block 8, a decoder 9. Nlock 6 consists of the first 10 and second II adders, the first 12, the second 13,

third 14 and fourth 15 multiplier and.

The digital device operates as follows.

The received signal from the input is fed to the amplifier 2, which automatically adjusts the gain according to the average value of the signal at its output. However, the average power adjustment does not provide accurate level tracking. Since the average input power does not ambiguously determine the nominal level of the signal at the output of the demodulation and compensation unit 7

The output signal from amplifier 2 with AGC directly and through phase shifter 3 is fed to analog-to-digital converter 4. Phaser 3 is a Hilbert converter and serves to form two orthogonal signals (subchannels R and Q).

Signals in digital form from the output of analog-to-digital converter 4 are fed to an adaptive equalizer 5, in which intersymbol interference correction is missing (MCI /. The corrected signal Y. arrives at block 6, which doesn’t have a precise adjustment of the signal level. The signal / output level control unit 6 is equal to

Z i- K.Y ,,

In block 7 of demodulation and phase compensation, the carrier oscillation is adjusted by forming the coordinate axes in accordance with the received signal. The signal V. at the output of block 7 of demodulation and phase phase computation is

V, /.,

),

where Cf is the angle of change of the phase of the carrier oscillation.

In decision block 8, estimates of the received signal V are formed in accordance with the used signal space, on the basis of which the decoder 9 in accordance with the manipulation code reconstructs the information sequence a, which then goes to the output.

Thus, the task of the decision block 8 includes the allocation of the correspondence of the signal V. at the output of the block 7 of demodulation and phase compensation to the reference value V.. By correspondence is meant the proximity (in the sense of the mean square distance) between V; and V, -.

In block 1 for calculating errors, signals fj are formed, corresponding to the deviation of the corrected signal V, from the reference value Vj, necessary for generating signals to control the operation of the adaptive corrector 5, blocks 6 and 7, according to the rule

e. V, - Vj.

Adaptive corrector 5 can correct the ISI according to the following algorithm:

(

J where C

..- e

+ / 3, e

J H - the complex transfer coefficient j-ro of the offset of the corrector at the i-th time instant, / 1 (- constant correction

error vector, reduced to the original coordinate axis.

, - ((

Block 6 monitors the signal level change in accordance with the algorithm.

, K, -n -1, B, (E. u.),

where d is constant regulation.

Phase compensation in block 7 of demodulation and compensation of phases

 where K; - block transfer coefficient 6, is by algorithm

., -, - ,,

 l - or

Where. 9; 1 „(e -Vj; 7 I j constant adjustments.

Claims (1)

Invention Formula A digital signal receiving device containing an amplifier with automatic gain control, an analog-to-digital converter, the outputs of which are connected to the inputs of an adaptive equalizer, serially connected demodulation and phase compensation unit, a decisive unit and a decoder, demodulation and compensation unit outputs the phases are connected to one of the inputs of the error calculation block, the other inputs B Which are connected to the outputs of the decision block, the first and second outputs of the error calculator are connected to the corresponding inputs of the demodulation and phase compensation and adaptive corrector, characterized in that, in order to improve the noise immunity, a level adjustment block is inserted between the outputs of the adaptive corrector and the inputs of the demodulation and phase compensation unit, the corresponding input of the level control unit is connected to the second output of the error calculator, the output of the amplifier with automatic adjustment the gain is connected to the first input of the analog-digital converter, as well as through a phase shifter with its second input. .2