SU1417201A1 - Method of spatial filtering of telegraph signals - Google Patents

Abstract

This invention relates to radio. The purpose of the invention is to increase the signal-to-noise ratio. To form complex weights, current, rather than delayed, values of alternative signals are used. Since a reference signal is formed that is most correlated with the reference signal, the dispersion of the phase adjustment error is small, i.e. an increase in the signal-to-noise ratio is achieved even in the presence of frequency-selective signal fading in the channel. 1 il.

Description

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The invention relates to radio technology and can be used in the equipment for receiving discrete signals.

The purpose of the invention is to increase the signal-to-noise ratio.

The drawing shows a block diagram of an apparatus for carrying out the method.

The device contains a radio receiver 1, the first block for calculating weights 2, the first multiplier 3, the second block for calculating weights 4, the second multiplier 5, the phase shifter 6, the adder 7, the first difference circuit 8, the second difference circuit 9, the first block forming the reference the signal 10, the second block forming the reference signal 11, the limiter 12, the detector 13, the low frequency filter 14, the regenerator of the information symbols 15, the inverter 16. The method is carried out as follows.

The received mixture of the signal and the mechs from the output of each radio receiving device 1 of the i-th channel is transmitted to the first computing unit 2 and the first multiplier 3 directly, and to the second computing unit 4 and the second multiplier 5 through

phase shifter 6 on, that provide- 35 exp

decomposition of the signal into quadrature components. The signals from the outputs of the multipliers are fed to the adder 7,. the output of which is. is the sum of weighted N channel signals of the antenna array (DR).

Next, the total signal is demodulated. This signal is limited in limiter 12, detected by detector 13, filtered by low-frequency filter 14, and fed to the input of the regenerator of information symbols 15. At the output of the regenerator of information symbols, the voltage changes according to the law of transmitted information. The error signal is then calculated by subtracting the total from the reference signal. The reference signals from the outputs of the first block forming the reference signal 10 and the second block forming the reference signal 1I are fed to the decremented inputs of the first difference circuit 8 and the second difference circuit 9, on the subtracted inputs of which the output signal of the adder is fed. At the outputs of the first and second difference circuits, the first and second error signals, respectively, that are received in the first and second blocks of the weighting factors calculation for calculating corrections, weighting coefficients

AW,; (t) And uW; (t).

For this, in blocks 2 and 4, the functions of mutual correlation of the input signal of the block and the corresponding error signal are calculated for the duration of one telegraphic sprinkling (for example, using mixers and an integrator). Then, the likelihood coefficient of each of the M-reference signals is calculated for the current telegraph endpoint X ",

 exp

(t) -djti,

where d (t) is the reference signal;

T - the duration of the telegraph

parcels;

Sj- is the total signal of the AR. At the end of the telegraph message, in each channel, the correction is calculated, which is calculated using the reference signal, for which the likelihood coefficient is maximum, and the complex weighting factor is calculated by the algorithm

 W; (KI) T W; (K.T) (t) S in, „; (t) dt К „(К + 1) t W; (KT-t-t) W; (CT)

where,, and the coefficient R onpe-

R.

1, if -Lg "Lnl m 1,2, ..., M, e y m O, if the condition is not fulfilled

The signal of the regenerator information symbols with the value of the weighting factor is summed up from the values flLW ,;) and AWjjCt), which is considered to be calculated correctly, i.e. This correction is the weighting coefficient, which is calculated using the reference signal whose presence at the adder's output is detected by the detector. Signal with. The output of the regenerator information symbols is fed to the first block for calculating the weighting coefficients and the first block forming the reference signal, having passed the inverter 16.

Claims (1)

To form complex weights, the current (rather than delayed) values of the output signals are used, and, since they form a reference signal that is most correlated with the reference signal, the phase adjustment error dispersion is small, i.e. signal-to-noise ratio is achieved, even in the presence of frequency-selective signal fading in the channel. Shadow Formula The method of spatial filtering telegraph signals, comprising that the output signal of each of the N channels of the antenna array is weighted by multiplying by the complex weighting factor, summarizing the output signals of all channels, demodulating the total signal, forming the reference signal, subtracting the total signal from the reference signal, g calculates the correction and refines the complex weighting factor in each channel, distinguishes n; iyc by the fact that, in order to increase the signal-to-noise ratio, they form (M-1) ds 5 additional reference signals, which are subtracted from the minimum signal, the correction is determined by calculating the mutual correlation between the output signal of each channel and 0 each value of the difference of the reference, and the total signal on the duration of the telegraph package, is calculated. Likelihood coefficient for each of the M reference signals for text 5 telegraph filings, in each channel choose the amendment corresponding to the maximum likelihood coefficient.