RU163605U1 - ADAPTIVE ADJUSTMENT SETTING OF THE CORRECTIVE FILTER WITH SYMPHAS COMPOSITION OF THE TEST - Google Patents

Abstract

A device for adaptive adjustment of a correction filter with in-phase addition of a test containing an n tap-off delay line, the input of which is the input of the device, from each of the n outputs of which test signals of length L are received, delayed by an interval equal to the length of the information signal L, an adder whose output is connected to the input a division block, the output of which is connected to the input of the block for calculating the impulse response of the correction filter, in which the impulse response of the correction filter is calculated, the output is an output of the device, characterized in that n-1 phase shifters are introduced, the first n1 outputs and the last n2 outputs of the n tap-off delay line connected to the first inputs n1 + n2 = n-1 of the corresponding phase shifters, the second input of which is connected to the 0th output n of the delay delay line, while in each phase shifter, the phase of the test signal received at the first input of the phase shifter is rotated, so that this test signal becomes in-phase with respect to the test signal supplied to the second input of the phase shifter For, the output of each phase shifter, as well as the 0th output n of the delay tap, are connected to the corresponding input of the adder, in which the received test signals are added up and, as a result, the total test signal is received at the output of the adder, which is transmitted to the input of the division block, in the division block, the total the test signal is divided by the averaging coefficient, receiving at the output an average total weighted test signal, which is transmitted from the output of the division block to the input of the block for calculating the impulse response of the correction filter.

Description

The utility model relates to the field of electro-radio engineering and communications, and can be used in single-frequency data transmission systems with adaptive correction of signals at the receiving side via channels with fading and intersymbol interference.

The essence of adaptive correction is to construct a correction filter that reduces signal distortions resulting from fading and multipath propagation in the communication channel, in particular, in the short-wave radio channel, for which periodic insertions of the test signal known on the receiving side are carried out in the transmitted signal. This approach is used in modern foreign standards, such as ARINC-635 and MIL-STD-188-110-B.

A device for adaptive adjustment of the correction filter is described in [Berezovsky V.A., Dulkeit I.V., Savitsky O.K. Modern decameter radio communication: equipment, systems and complexes / Ed. V.A. Berezovsky. - M .: Radio engineering, 2011. - 444 p.]. The device comprises a block for calculating the impulse response of the correction filter, in which the impulse response of the correction filter is calculated, the output of which is the output of the device. To calculate the impulse response of the correction filter, in the block for calculating the impulse response of the correction filter, for example, the matrix filter method can be implemented [V. Berezovsky, I. V. Dulkeit, O.K. Savitsky. Modern decameter radio communication: equipment, systems and complexes / Ed. V.A. Berezovsky. - M.: Radio Engineering, 2011. - 444 p.], The method of least squares (LMS algorithm)

[Dzhigan V.I. Adaptive signal filtering: theory and algorithms. M .: Technosphere, 2013. - 528 p.], Or the RLS algorithm [Dzhigan V.I. Adaptive signal filtering: theory and algorithms. M .: Technosphere, 2013. - 528 p.]. The choice of a specific calculation algorithm is determined based on the required convergence rate and computational capabilities.

The disadvantages of such a device include the fact that at low signal-to-noise ratios, the accuracy of the adjustment filter adjustment is significantly impaired, which leads to a decrease in the quality of correction, and as a result, a decrease in noise immunity.

Closest to the claimed technical solution is a device for adaptive adjustment of the correction filter with quasi-coherent addition of the test, RF patent for utility model No. 148638 published December 10, 2014, adopted as a prototype. The device contains n delay delay line, the input of which is the input of the device, from each of the n outputs of which test signals of length L _T are received, delayed by an interval equal to the length of the information signal L _AND , an adder whose output is connected to the input of the division unit, the output of which is connected to the input of the block calculating the impulse response of the correction filter, in which the impulse response of the correction filter is calculated, the output of which is the output of the device.

The disadvantages of the prototype include the fact that in channels in which the impulse response of the channel changes rather quickly over time, the addition of several test signals cannot be considered quasi-coherent, as a result of this addition, the accuracy of the adjustment filter is reduced, which leads to a decrease in the quality of correction, and as a result reduce noise immunity.

The purpose of the utility model is to increase the accuracy of calculating the impulse response of the correction filter and, as a result, increase the noise immunity.

This goal is achieved by the fact that in the adaptive adjustment device of the correction filter with in-phase addition of the test, containing an n tap delay line, the input of which is the input of the device, from each of the n outputs of which test signals of length L _T are received, delayed by an interval equal to the length of the information signal L _And , the adder, the output of which is connected to the input of the division unit, the output of which is connected to the input of the calculation unit of the impulse response of the correction filter, in which the impulse response is calculated The characteristics of the correction filter, the output of which is the output of the device, include an n-1 phase shifter, the first n1 outputs and the last n2 outputs n of the output delay line connected to the first inputs n1 + n2 = n-1 of the corresponding phase shifters, the second input of which is connected to the 0th the output of the n-delay delay line, while in each phase shifter, the phase of the test signal is transmitted to the first input of the phase shifter, so that this test signal becomes in phase with respect to the test signal supplied to the second input of the phase shifter, the output of each phase shifter, as well as the 0th output n of the output delay line are connected to the corresponding input of the adder, in which the received test signals are added up and, as a result, the total test signal, which is transmitted to the input of the division block, is received in the block dividing the total test signal is divided by the averaging coefficient, receiving at the output an average total weighted test signal, which is transmitted from the output of the division unit to the input of the impulse response calculation unit to correction filter.

The structural diagram of the proposed device is shown in Fig 1. It contains n delay delay line 1, the input of which is the input of the device, the first n1 outputs and the last n2 outputs of which are connected to the first input n-1 = n1 + n2 of the corresponding phase shifters 2.-n1, ... 2.-1, 2.1 ... 2.n2, the second input of which is connected to the 0th output n of the branch line

delays 1. The output of each n-1 = n1 + n2 of the phase shifter 2.-n1, ... 2.-1, 2.1 ... 2.n2, as well as the 0th output of the n delay delay line 1 are connected to the corresponding n inputs of the adder 3. Output the adder 3 is connected to the input of the division unit 4. The output of the division unit 4 is connected to the input of the calculation unit of the impulse response of the correction filter 5, the output of which is the output of the device.

The operation of the device is as follows.

The input n of the delay delay branch 1, the input of which is the input of the device, receives a signal containing periodically repeated test and information signals. The structure of such a signal is shown in FIG. 2. The length of each test signal is L _T , the length of each information signal L _AND . The number of taps (outputs) of the delay line 1 equal to n can be different and is selected based on the specific application. For example, a delay in the processing of information signals may be unacceptable, n2 in this case will be 0. From each of n outputs n of the output delay line 1 test signals of length L _T are received, delayed by an interval equal to the length of the information signal L _AND . At the same time, from the first n1 and last n2 outputs n of the branch delay line 1, the test signals are fed to the first input of the corresponding n-1 = n1 + n2 phase shifters 2.-n1, ... 2.-1, 2.1 ... 2.n2. And from the 0th output n of the drain delay line 1, the test signal is fed to the second input of each of the n-1 phase shifters 2.-n1, ... 2.-1, 2.1 ... 2.n2.

In each phase shifter 2.-n1, ... 2.-1, 2.1 ... 2.n2, the phase of the test signal received at the first input is rotated so that this test signal becomes in phase with respect to the test signal supplied to the second input. That is, in each phase shifter 2.-n1, ... 2.-1, 2.1 ... 2.n2, the phase difference Δφ between the test signals received at the first and second inputs is estimated, and then the phase of the test signal received at

the first input, at an angle Δφ and transmit it to the output of the phase shifter 2.-n1, ... 2.-1, 2.1 ... 2.n2. Methods for assessing the phase difference are described in [M.K. Chmykh. Digital phase metering. - M .: Radio and communications, 1993. - 184 p.]. The implementation of the phase rotation of the test signal can be carried out, for example, using the device described in the patent of the Russian Federation No. 23033326 of July 20, 2007. A few more options for the implementation of phase shifters 2.-n1, ... 2.-1, 2.1 ... 2.n2 are also described in the publication [Sartasov N.A., Edvaby V.M., Gribin V.V. Short-wave trunk radio receivers, M.: “Communication”, 1971. - 288 p.], In particular on p. 185 images 5.146.

The test signals from the output of each of the phase shifters 2.-n1, ... 2.-1, 2.1 ... 2.n2, as well as the test signal from the 0th output n of the bypass delay line 1, are supplied to the corresponding n inputs of the adder 3. In the adder 3 carry out the addition of n test signals, as a result of which the sum of the test signal is received at the output of the adder 3, which is transmitted to the input of the division unit 4. In the division unit 4, the total test signal is divided by an averaging coefficient equal to n, obtaining an average total test signal whose power is close to power od th test signal and noise power in less time n. From the output of the division unit 4, the averaged total test signal is fed to the input of the block for calculating the impulse response of the correction filter 5, the output of which gives the desired impulse response of the correction filter necessary for subsequent adjustment of the correction filter. To calculate the impulse response of the correction filter, in the block for calculating the impulse response of the correction filter 5, for example, the matrix filter method can be implemented [V. Berezovsky, I. V. Dulkeit, O.K. Savitsky. Modern decameter radio communication: equipment, systems and complexes / Ed. V.A. Berezovsky. - M .: Radio engineering, 2011. - 444 p.], The method of least squares (LMS algorithm) [Dzhigan V.I. Adaptive signal filtering: theory and algorithms. M .: Technosphere,

2013. - 528 p.], Or the RLS algorithm [Dzhigan V.I. Adaptive signal filtering: theory and algorithms. M .: Technosphere, 2013. - 528 p.].

The result obtained at the output of the block for calculating the impulse response of the correction filter 5 is the impulse response in the form: h (m), m = 0 ... M-1, where M is the final number of coefficients of the correction filter, which is a filter with a finite impulse response.

The proposed device can be used in systems of single-frequency data transmission with adaptive correction of signals at the receiving side, on channels with fading and intersymbol interference. The proposed device provides improved accuracy in calculating the impulse response of the correction filter, and as a result, increased noise immunity, including in channels with a rapid change in impulse response over time, due to the in-phase addition of test signals and increase the signal-to-noise ratio.

Claims (1)

A device for adaptive adjustment of a correction filter with in-phase addition of a test, containing an n tap delay line, the input of which is the input of the device, from each of the n outputs of which test signals of length L _T are received, delayed by an interval equal to the length of the information signal L _AND , the adder whose output is connected with the input of the division block, the output of which is connected to the input of the block for calculating the impulse response of the correction filter, in which the impulse response of the correction filter is calculated, you One of which is the output of the device, characterized in that n-1 phase shifters are introduced, the first n1 outputs and the last n2 outputs of the n tap-off delay line connected to the first inputs n1 + n2 = n-1 of the corresponding phase shifters, the second input of which is connected to the 0th output n of the delay delay line, while in each phase shifter, the phase of the test signal is transmitted to the first input of the phase shifter, so that this test signal becomes in-phase with respect to the test signal supplied to the second input of the phase shifter The output, the output of each phase shifter, as well as the 0th output n of the drain delay line are connected to the corresponding input of the adder, in which the received test signals are added up and, as a result, the total test signal is received at the output of the adder, which is transmitted to the input of the division unit, in the division unit, the total the test signal is divided by the averaging coefficient, receiving at the output an average total weighted test signal, which is transmitted from the output of the division block to the input of the block for calculating the impulse response of the correction filter pa.

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