RU160468U1 - DIGITAL COMPENSATOR RESPONDER INTERFERENCE - Google Patents

Abstract

A digital transponder interference compensator containing N + 1 channels from a series-connected antenna, microwave path, intermediate frequency path, a bandpass filter and an analog-to-digital quadrature converter, as well as a digital processor and weight summation unit, in which N inputs of complex samples of additional channels are connected with the outputs of the corresponding analog-to-digital quadrature converters, a N control inputs connected to the outputs of the digital processor, characterized in that N + 1 shear x registers connected between the outputs of the analog-to-digital quadrature converters and the corresponding inputs of the digital processor, and a request decoder connected to the output of the compensator, the output of the request decoder being connected to the reset input of each shift register, the output of the request decoder is the start output of the responder transmitter.

Description

The utility model relates to radio communications and radar, in particular, to multi-channel receiving devices with suppression of interference signals used in request-response systems, and can be used in radio systems of other purposes.

The prior art in the field of radio communications, which is associated with suppressing the effects of interfering signals using adaptive antenna systems (or, in other words, interference compensators), can be determined from the following classic monographs: 1) Monzingo R.A., Miller T.U. “Adaptive Antenna Arrays: Introduction to Theory”: Per. from English - M .: Radio and communications, 1986. - 448 p .; 2) Pistolkors A.A., Litvinov O.S. "Introduction to the theory of adaptive antennas" - M .: Nauka, 1991; 3) Sheshniak S.S., Popov M.P. “Adaptive Antennas” - St. Petersburg: Publishing House VIKKA them. A.F. Mozhaysky, 1995 .-- 800 p. It is noted that one of the problems is to protect the adaptation circuits from the effects of useful signals and thereby prevent the formation of pattern failures (DF) on the sources of useful signals.

The closest in technical essence to the proposed device is a digital compensator device described and implementing the method of interference compensation claimed in RF patent No. 2271066 C2 (IPC Н04В 1/10) from 2006. The specified device is taken as a prototype. It is a digital version of the implementation of an adaptive antenna array (AAR) with compensating elements as in a functional diagram (see Choni Yu.I. “Adaptive Antennas of Communication and Telecommunication Systems”, Kazan: Publishing House “New Knowledge”. - 2012. p. 53, Fig. 3.3), and according to the VK calculation algorithm (see ibid., Lower line of formula (4.30) on page 77).

In FIG. 1 shows a slightly modified structural diagram for the purpose of greater clarity, a digital interference compensator - a prototype, where it is indicated:

1 - the main antenna under the number "0";

2 - additional antennas (total N);

3 - microwave paths;

4 - frequency conversion paths (TFC);

5 - analog bandpass filters (PF);

6 - analog-to-digital quadrature converters (ATsKP);

7 - digital processor (CPU);

8 - delay elements for time L;

9 - multipliers;

10 - adders;

11 - weight summation unit

Block weight summation 11, combine the following elements of the structural diagram of the prototype together with their relationships: delay elements 8, multipliers 9 and adders 10.

The prototype device operates as follows.

Compensation for interference is carried out at the video frequency. For this, the signal of each element of the antenna array consisting of the main antenna 1, in FIG. 1 and one or several (total N) identical additional antennas 2, after passing through the microwave path 3 and the frequency conversion path 4, as well as limiting the passband for sampling the analog bandpass filter 5, is converted into a digital complex signal in an analog-to-digital quadrature converter 6 The sampling frequency F _d in the ADC included in the ADC in all channels should be the same. The received signals at the video frequency are used by the digital processor 7 as input to calculate the N complex optimal weighting coefficients (VK) w ₁ ... w _N using an adaptive algorithm for reversing a sample correlation (covariance) matrix. For this, a preliminary correlation matrix and cross-correlation vector are compiled from the final samples of input signals (possibly thinned out) in different channels related to the same time. The adaptive algorithm calculation time must satisfy the requirements of real time, i.e. weighting coefficients must be calculated in a time shorter than L. The samples of the compensation channel signals delayed by their duration in the delay elements 8 are multiplied (multipliers of real numbers are indicated by 9) by the corresponding signals, i.e. calculated by them, weights. After that, the multiplication results are added to the adders 10, forming a compensation signal, which is subtracted from the sample of the main channel signal delayed by the same time in the latter before the output of the compensator of the two adders 10.

The advantage of the prototype is that in the main channel, an antenna with a wide or isotropic beam covering the desired working area can be used.

The disadvantage of the prototype when used in the composition of the receiver of the responder is the fact that the interrogation signals present in the channel samples distort the matrix of correlation coefficients of the interfering signals and, as a result, the VC deviates from the optimal values. This is manifested in the formation of dips on the interrogator and in the weakening of interference compensation.

The main task to which the claimed utility model is directed is to eliminate the influence of interrogation signals on the process of compensation of interfering signals. Naturally, the time L of accumulation of samples in the CPU significantly exceeds the duration of the request T _s , which is a short-term pulse sending.

The technical result achieved by the implementation of the proposed technical solution is to reduce the influence of the interrogation signal on the result of compensation for interference in the defendant.

The specified technical result is achieved by the fact that in the well-known digital noise equalizer containing the main channel and N channels from a series-connected antenna, microwave, frequency conversion path, bandpass filter and analog-to-digital quadrature converter, as well as a digital processor and weight summation unit, N the inputs of complex samples of which are connected to the outputs of the corresponding analog-to-digital quadrature converters, and N control inputs are connected to the outputs of the digital processor, agrees about the proposed technical solution, N + 1 shift registers were additionally introduced for the request duration T _s included between the outputs of the analog-to-digital quadrature converters and the corresponding inputs of the digital processor, and a request decoder connected to the output of the compensator, and the output of the request decoder is connected to the reset input each shift register and is the output of the start of the transmitter of the responder.

The analysis of the prior art cited by the applicant made it possible to establish that there are no analogs characterized by sets of features identical to all the features of the claimed digital compensator for the interference of the respondent. Therefore, the claimed technical solution meets the conditions of patentability "novelty."

The results of the search for known solutions in the art in order to identify features that match the distinctive features of the prototype of the proposed technical solution showed that they do not follow explicitly from the prior art. From a certain applicant follows clearly from the prior art. From the prior art determined by the applicant, the influence of the transformations provided for by the essential features of the claimed technical solution on the achievement of the specified technical result has not been revealed. Therefore, the claimed technical solution meets the condition of patentability "utility model".

In FIG. 2 depicts a block diagram of the inventive digital transducer interference canceller, where the double lines reflect the inputs and outputs for complex quantities represented by Re and Im signals.

The digital compensator of the transponder interference contains the main antenna 1 and N additional antennas 2, to which are connected N + 1 identical channels from the series-connected microwave path 3, the frequency conversion path 4, the bandpass filter 5 and the analog-to-digital quadrature converter 6, as well as a digital processor 7 and the weight summation block 11, in which N + 1 inputs of complex samples are connected to the outputs of the corresponding analog-to-digital quadrature converters 6, and N control inputs of the weight summation block are connected to the output I will give a digital processor 7, the outputs of the intermediate frequency signal are connected to the corresponding inputs of each analog-to-digital quadrature converter 6, N + 1 of the shift registers 13 connected between the outputs of the analog-to-digital quadrature converters 6 and the corresponding inputs of the digital processor 7, and a request decoder 12 connected to the output of the weight summation block 11, and the output of the request decoder 12 is connected to the input "reset" of each shift register 13.

The device operates as follows.

The received signals, or rather their complex envelopes, digitized, exactly as in the prototype are fed to the inputs of the compensation unit 11. The samples of the complex amplitudes x _n (t _k ) (n = 1 ... N) of the additional channels are weighted in accordance with the values of the weight the coefficients w _n received at the control inputs of the compensation unit from the outputs of the CPU 7. Thus, a signal is generated at the output of the compensation unit

The digital processor implements the correlation matrix inversion algorithm

W = <Z> ^-1 R ₀ ,

, где P^П - мощность помех на выходе цепи компенсации. Таким образом, минимизируется мощность помех при возможно меньшем возбуждении дополнительных элементов антенной решетки, т.е. возможно меньшем отклонении текущей ДН от исходной.where W = {w ₁ , ... w _N } is the vector of weighting factors N of the additional channels, <Z> is the correlation matrix of samples {x ₁ (t _k ), ... x _N (t _k )}, R ₀ is the vector of coefficients of cross-correlation of samples {x _{1 (t k), ... x N} (t k)} with the sample base channel x ₀ (t _k). If the samples are generated only by interfering signals, then, as shown in the book of Choni Yu.I. “Adaptive antennas of communication systems and telecommunications”, Kazan: Izd. "New knowledge." - 2012, weight coefficients W are optimal in the sense of a minimum of functional

where P ^P is the interference power at the output of the compensation circuit. Thus, the interference power is minimized with the least possible excitation of additional elements of the antenna array, i.e. possibly less deviation of the current day from the original.

When the signal from the interrogator request decoder 12 at the end of the interrogation signal produces a pulse, which resets (clears) the shift registers 13. Since the capacity of the shift registers 13 corresponds to the duration T _of the interrogation signal, the reset entered into the shift register 13, interrogation signal. Thus, in the samples received for processing in the CPU 7 for calculating the VK VK, the useful signals of the interrogators do not fall, and thus the VK are calculated only from the signals from the interference sources. The influence of the useful signal on the interference compensation process does not occur. At the same time, the pulse of the decoder request 12 starts the transmitter of the responder.

An example implementation of a six-channel digital equalizer is shown in FIG. 3. From the outputs of the intermediate frequency of the transponder receivers, the intermediate frequency signal of the order of 90-100 MHz with a band equal to the passband of the analog part of the receiver is fed to the input of the ADC 5101НВ015 for conversion to discrete samples of the intermediate frequency. From the ADC output, a 12-bit digital bus is connected to the input of the IS1897VB015 digital receiver, where the transfer from the intermediate frequency to zero is performed, digital filtering and decimation of the samples in accordance with the bandwidth of the received signal. From the output data bus of the digital receiver microcircuit, samples of complex amplitude are transmitted for further processing to the FPGA 5578TC024, which implements the functions of a shift register on T _s and a CPU that calculates weight coefficients. In the same FPGA, operations of multiplication and summation are performed in accordance with the compensation algorithm described above. As a result of all these operations, the signal from the output FPGA data bus, which is the output signal of the compensator x _out (t _k ) in the form of samples on the parallel data bus, is sent for further decryption to the second FPGA 5578TC024, which implements the responder’s functionality and controls the register reset via the corresponding communication line FPGA CPU.

Claims (1)

A digital transponder interference compensator containing N + 1 channels from a series-connected antenna, microwave path, intermediate frequency path, a bandpass filter and an analog-to-digital quadrature converter, as well as a digital processor and weight summation unit, in which N inputs of complex samples of additional channels are connected with the outputs of the corresponding analog-to-digital quadrature converters, a N control inputs are connected to the outputs of the digital processor, characterized in that N + 1 shear x registers connected between the outputs of the analog-to-digital quadrature converters and the corresponding inputs of the digital processor, and a request decoder connected to the output of the compensator, the output of the request decoder being connected to the reset input of each shift register, the output of the request decoder is the start output of the responder transmitter.

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