RU2716027C1 - Useful signal correlator with detection and classification of interference - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to radio electronic equipment and can be used in information transmission systems to determine the correspondence of a code received from a signal transmitter to a code stored in the receiver memory. Technical result is achieved due to the fact that the disclosed solution includes: an interference generator, antennae, an amplifier, an analogue-to-digital converter, a comparison processor, a coincidence counter, a synchroniser, a resolution circuit, a microprocessor, an interference indicator, and a reference interference unit.

EFFECT: technical result is broader functional capabilities of correlator due to analysis of noise damaging useful signal.

1 cl, 1 dwg

Description

The invention relates to electronic equipment and can be used in information transfer systems to determine the correspondence (identity) of a code received from a signal transmitter to a code stored in the receiver's memory.

In the general case (from the point of view of theory), a correlator is a device capable of calculating the correlation function between two processes.

It can also be used to calculate the correlation function under conditions of artificial or natural interference, when the received signal is seriously damaged.

It is preferable to use it to perform not only for its main function (calculating the correlation), but also perform the primary analysis of interference that has damaged a useful signal, especially with regard to communication channels using noise-like signals.

The use of correlators in digital communication systems used to transmit information for discrete log states. "Zero" or log. the “unit” implementation of the correlators is classic, see Varakin JI.E. "Communication Systems with Noise-Like Signals, M, Radio and Communications, 1985, p. 384.

The problem is the technical implementation of correlators using quasi-harmonic pulses.

There is a theoretical development for the implementation of such a correlator, see "Investigation of the ACF of noise-like signals with pulses of a harmonic shape with a limited width of the spectrum." Malygin I.V., Komissarova A.V. In the collection: microwave equipment and telecommunication technologies 25th International Crimean Conference. 2015.

The disadvantage of this development: this is only a theory, but it is still far from a practical implementation.

The closest technical solution is the RF patent for the invention, see No. 2618941 "Correlator", which for all its advantages does not recognize the type of interference and does not classify them.

This patent is chosen as an example of creating an interference recognition analysis based on it, but this method can be used for others, not only rectangular and quasi-harmonic correlators, but also for other signals, and small circuit changes - functional ones will be required.

An object of the invention is to expand the functionality of the correlator.

The technical result is achieved by analyzing interference that damages the useful signal, their classification and restoration of the useful signal.

One of the applications of noise-like signals in communication systems is to increase noise immunity. In the most general case, the noise immunity of a noise-like signal is determined by its base. To recognize the received noise-like signal, a correlator or a matched filter is used. The correlator's task is to compare the received signal with the original stored in the receiver's memory in order to find a match (correlation) and tell if such a match takes place. Noise immunity in this case means that the received signal can be seriously damaged, however, the correlator recognizes it.

In the event that the received signal is damaged by external interference of a different nature and origin, then the type of interference that caused them can be judged by the nature of the damage. Knowing the type of interference can be critical in order to make the necessary changes to various parameters of the radio channel transceivers to continue its operation.

This solution proposes a correlator, which not only performs its main function - finding the correlation, but also performs an initial analysis of the noise that damaged the signal. The analysis can be carried out both on the basis of a microcontroller or hard logic devices, and on the basis of a trained neural network.

To solve this problem, a correlator of a useful signal with detection and classification of interference is proposed, containing the correlator itself, characterized in that an interference signaling device is introduced, which together have the following connections. The output of the transmitter of noise-like signals through the antenna A2 is connected by a radio channel to the antenna A3 of the correlator, with which the output of the generator of various noise through the antenna A1 is also connected by another radio channel.

The input signal bus from antenna A3 (a mixture of useful signal, interference, and noise) is connected via the LNA to the ADC signal input, the outputs of which are connected to the first input of the comparison processor, the first output of which is connected to a coincidence counter, the first output of this counter is connected to a synchronizer, the output of which connected to the resolution circuit, and the second output of the coincidence counter through the shift register and through the storage device is connected by a bi-directional bus to the second input of the microprocessor, the third input of which is connected to the start input of reading and synchronizing the ADC, and the fourth output of the MP via the AGC bus is connected to the LNA, the second output of the MP is connected to the first input of the microcontroller, the output of which is connected to the first input of the interference mixture indicator, and the output of the latter through the model interference block is connected to the second input of the MC and to the second input MP.

The correlators with the function of interference analysis that damage the useful signal and its restoration are not known to the author from known sources.

The drawing shows a functional electrical diagram of the correlator, which shows:

1 - transmitter noise-like signals;

2 - generator of various interference (natural and / or artificial);

3 - low noise amplifier with filters;

4 - ADC;

5 - microprocessor (MP) comparison;

6 - ROM;

7 - hit counter;

8 - shift register;

9 - synchronizer;

10 is a signal resolution scheme (CXP);

11 is a block of model interference;

12 - indicator of a mixture of interference;

13 - microcontroller (MK);

A1 and A2 - transmitting antennas;

A3 - reinforced antenna;

B - correlator;

B - interference analyzer.

The correlator of useful signals with the detection and classification of interference has the following connections.

The output of the transmitter of noise-like signals 1 through the antenna A2 is connected by a radio channel to the antenna A3 of the correlator, to which also another radio channel is connected the output of the generator of various interference 2 through the antenna A1.

The input signal bus from antenna A3 (a mixture of useful signal, interference, and noise) is connected via the LNA 3 to the ADC 4 signal input, the outputs of which are connected to the first input of the comparison processor 5, whose first output is connected to coincidence counter 7, and the first output of this counter is connected to synchronizer 9, the output of which is connected to the resolution circuit 10, and the second output of the coincidence counter 7 through the shift register 8 and through the storage device 6 is connected by a bi-directional bus to the second input of the microprocessor 5, the third input of which is connected to the ADC reading and synchronization start house 4, and the fourth output of the MP 5 is connected to the LNA 3 by the AGC bus, the second output of the MP 5 is connected to the first input of the microcontroller 13, the output of which is connected to the first input of the interference indicator 12, and the output of the latter through the model interference block 11 connected to the second input of MK 13 and to the second input of MP 5.

The correlator works as follows.

A mixture of useful signal, noise and noise from the output of the high-frequency part of the receiver through the LNA is fed to the input of the ADC, where it is converted to digital form. The comparison processor, bit by bit, with the required clock frequency, checks the correspondence of the received signal with the source code stored in the device’s memory. If the number of matches is insufficient, determined by the counter of coincidences on the output signal of the comparison processor, the shift register shifts the code in memory to the right (or left) by one clock cycle, after which the comparison procedure is repeated. The coincidence counter and the shift register should be implemented on one FPGA. If the number of matches, ideally equal to the length of the used pseudo-random sequence, is sufficient, the synchronizer generates a synchronization pulse to start receiving useful information by the receiving device. The synchronizer can be implemented on the basis of a microcomputer. A separate memory microcircuit is not planned, since processor memory, FPGA memory, and microcomputer memory can be used for this purpose. In this case, a sequential correlator circuit is described; to accelerate the correlation procedure, a parallel circuit can also be applied, which will require the use of microcircuits of greater capacity and processing power.

The interference analyzer operates as follows.

Consider the principle of the correlator using an example of an M-sequence with a length of 31 bits.

If the effect of narrow-band interference on the useful signal is not continuous, but pulsed, then the temporal parameters of the interference can be estimated by comparing the frequency of occurrence of the described damage in the body of the M-sequence.

If the M-sequence received by the receiver contains several damaged sections, then there were several narrow-band interference: 0000XXX00101XXXX111XXX100010XXX1

If the interference is broadband, the damage range will be much larger: 0000XXXXXXXXXXXXX10101000100111

Using the proposed correlator allows you to supplement the communication equipment with additional research and analysis functions, which can improve its characteristics statistically.

A mixture of useful signal, noise and noise from the output of the high-frequency part of the receiver is fed to the ADC input, for example, AD7903 from Analog Devices, where it is converted to digital form. The comparison processor, for example, STM32F3 by STMicroelectronics, checks the correspondence of the received signal with the source code stored in the device memory bit by bit, with the required clock frequency. If the number of matches is insufficient, determined by the counter of coincidences on the output signal of the comparison processor, the shift register shifts the code in memory to the right (or left) by one clock cycle, after which the comparison procedure is repeated. It is advisable to implement the coincidence counter and the shift register on one FPGA, for example, Altera EPM240T100C5. If the number of matches, ideally equal to the length of the used pseudo-random sequence, is sufficient, the synchronizer emits a synchronization pulse to start receiving useful information by the receiving device. The synchronizer can be implemented on the basis of a microcomputer. A separate memory microcircuit is not planned, since processor memory, FPGA memory, and microcomputer memory can be used for this purpose. In this case, a sequential correlator circuit is described; to accelerate the correlation procedure, a parallel circuit can also be applied, which will require the use of microcircuits of greater capacity and processing power.

List of references

1. Varakin L.E. Communication systems with noise-like signals. M .: Radio and communications, 1985 .-- 384 p., Ill.

2. The study of ACF noise-like signals with pulses of a harmonic shape while limiting the width of the spectrum. Malygin I.V., Komissarova A.V. In the collection: microwave equipment and telecommunication technologies 25th International Crimean Conference. 2015.

3. RF patent No. 2618941, priority dated September 15, 2015.

Claims (1)

The correlator of the useful signal with the detection and classification of interference, containing the output of the transmitter of noise-like signals through the antenna A2, is connected by a radio channel to the antenna A3 of the correlator, which also connects to the other radio channel the output of the generator of various interference through the antenna A1; the input signal bus, which receives a mixture of useful signal, noise and noise from antenna A3, is connected through a low-noise amplifier (LNA) to the ADC signal input, the outputs of which are connected to the first input of the comparison processor, the first output of which is connected to the coincidence counter, the first output of this the counter is connected to a synchronizer, the output of which is connected to a resolution circuit, and the second output of the coincidence counter is connected via a shift register and through a storage device with a bi-directional bus to the second input of the microprocessor, the input of which is connected to the input of the ADC reading and synchronization, and the fourth output of the MP via the AGC bus is connected to the LNA, the second output of the MP is connected to the first input of the microcontroller, the output of which is connected to the first input of the interference mixture indicator, and the output of the latter through the model interference block is connected to the second input of the MK and with the second input of the MP.

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