WO2020171735A1

WO2020171735A1 - Method of energy signal detection

Info

Publication number: WO2020171735A1
Application number: PCT/RU2019/000662
Authority: WO
Inventors: Vladimir Aleksandrovich BELOGUROV; Vladimir Alekseevich ZOLOTAREV
Original assignee: Joint-Stock Company "Concern "Sozvezdie"
Priority date: 2019-02-20
Filing date: 2019-09-23
Publication date: 2020-08-27
Also published as: RU2700580C1

Abstract

The invention belongs to the field of communication technology and can be used in communications. Technical result - decrease in the time spent on assessing the interference power, and thus increasing the speed of information exchange in the presence of interference. In the method of energy detection of the signal with compensation of the combinatorial components of the signal and interference in the main and compensatory channels, the additive mixture of signal and interference is branched and processed in the same way in the main and compensatory channels: the signal after squaring is simultaneously filtered by the lowpass filter (LPF), the band of which is coordinated with the signal bandwidth, and the bandpass filter (BPF), in which the upper frequency corresponds to the upper frequency of the signal, and the value of the lower frequency is as close as possible to zero; they calculate the sum of the differences between the readings of the signal and interference mixture that passed the filters. In the compensation channel, the readings of the signal and interference mixture, which has passed the filters, are taken with a time shift, the value of which is determined in advance. They calculate the signal amplitude value using the stored voltage values obtained in the channels. Conclusion about the signal type is made by comparing the signal amplitude with the corresponding threshold.

Description

METHOD OF ENERGY SIGNAL DETECTION

Field of technology

This method is related to radio engineering and can be used in communications .

Previous technology state

There are known methods which are realized by suppression devices of the narrowband interference described in a.s. No. 1688416 H04B 1/10, and also in patents of the Russian Federation No. 2034403 H04B 1/10, No. 2204203 H04B 1/10, by the device of compensation of the narrowband interference described in the article of Efimov V.P. "Evaluation of the influence of nonlinear transformation on the noise immunity of reception in satellite networks", published in the journal "Electromagnetic waves and electromagnetic systems", No. 1, vol. 3, 1998, p. 95, the disadvantage of which is a low degree of interference suppression.

There are known methods that are implemented by suppression devices of the broadband interference described in patents RU 2115234, H04B 1/10, RU 2143783, H04B 1/10, RU 2190297 H04B 1/10, the disadvantage of which is a low degree of noise suppression.

There is a know Price-Urkowitz method of energy detection described in the textbook "Fundamentals of the theory of radio engineering systems". Textbook. // V. I. Borisov, V. M. Zinchuk, A. E. Limarev, N. P. Mukhin. Edited by V. I. Borisov. Voronezh Research Institute of Communications, 2004, pp. 75- 76. The disadvantage of the method is the low noise immunity of communication facilities in the presence of interference such as additive white Gaussian noise, as well as the complexity of practical implementation, associated with a long time of assessment of the interference power. The closest to the technical essence is the method of signals separation in the presence of interference, described in the patent RU No. 2675386 H04B 1/10 , taken as a prototype.

The prototype method is that the additive mixture of signal and interference is processed in the linear path of the receiver, after which the signal is erected in a square, the signal after squaring is filtered by a lowpass filter (LPF), the bandwidth of which is consistent with the signal bandwidth. At the same time, the signal is filtered by a bandpass filter after squaring, the bandpass is selected in such a way that the upper frequency of the bandpass filter corresponds to the upper signal frequency, the lower frequency of the bandpass filter is selected as close as possible to zero. The choice LPF and the bandpass filters shall be carried out with the maximum phase and frequency response identical to each other and in such a way that the sum of the differences in the LPF amplitude and bandpass characteristics taken for all frequencies is as small as possible. Formed in digital form, by converting the corresponding analog-to-digital converters (ADC), the signals sample that passed the bandpass filter and LPF, these values are subtracted from one another in the computing device, the obtained values are summed up and stored; from the received amount subtracted the value of power interference, which is obtained as follows - filter the interference with the same LPF, which is filtered by a mixture of signal and interference, at the same time filter the interference with the same bandpass filter, which filter the mixture of signal and noise, form a digital form by converting to the appropriate ADC, noise samples that passed LPF and bandpass filter, these values are subtracted from one another, the obtained values are summed up and stored, this value of the noise power is obtained during the time interval of the noise analysis, which is located just before the processed information symbol, and which contains only the interference; decide on the presence of the signal by comparing with the threshold.

The disadvantage of the prototype method is that to ensure the estimation of the interference power they form a time interval in which there is no signal, which leads to a decrease in the speed of information exchange. Disclosure of the invention

The declared invention solves the problem of reducing the time spent on the interference power estimation and thus increasing the speed of information exchange in conditions of interference, including the type of additive white Gaussian noise (AWGN).

To solve the problem in the way that the additive mixture of signal and interference is processed in the linear path of the receiver, after which the mixture of signal and interference is squared, after squaring the resulting signal is filtered by a lowpass filter (LPF), the bandwidth of which is consistent with the signal bandwidth; simultaneously, the received signal is filtered by the bandpass filter, the bandpass of which is selected so that the upper frequency of the bandpass filter corresponds to the upper frequency of the signal, the lower frequency of the bandpass filter is selected as close as possible to zero; the selection of the LPF and bandpass filter is carried out with the maximum identical phase-frequency characteristics relative to each other and so that the minimum possible value of the sum of differences in the values of amplitude-frequency characteristics of the LPF and bandpass filter is provided they form digitally by conversion in the corresponding analog-to-digital converters (ADC) the signals samples that passed bandpass filter and LPF, these values are subtracted from one another in the computing device, the obtained values are summed up and stored, according to the invention, the mixture of signal and interference at the output of the receiver's linear path is branched; in the compensation channel, the mixture of signal and interference is processed in the same way as in the main channel, while the readings of signals that passed the bandpass filter and LPF are performed, the value of which is determined in advance, the sum of the differences between the readings of the signals that passed the bandpass filter and the readings of the signals that passed the LPF filter, are memorized, they calculate the value of the signal amplitude using the memorized values of voltages received in the main and compensation channels, the conclusion about the presence of the first or second type signals is made by comparing the obtained value of the signal amplitude with the corresponding threshold. Implementation option of the invention.

The method for using amplitude-modulated (AMn) signals and fixed frequency operation is described. In case of frequency tuning, the process is carried out for each operating frequency as well as for a fixed frequency.

Two types of signal are formed. Signals of different types differ in amplitudes by a specified number of times:

KaH i/Lh, (1) where: K_ar - amplitudes ratio of signals of different types;

U1 , U2 - amplitudes of signals of the first and second type.

It is believed that synchronization has been carried out at the time of communication, and the position in the signal start time is known with sufficient accuracy to carry out the subtraction and summation of the signals with the necessary efficiency.

A given performance level is defined as the the probability of signal detection is at least as good as a given level and the probability of a false alarm will not exceed a given level.

After processing in the main channel the voltage is equal to the sum of squares of signal amplitudes and interference components

where: U_s - signal amplitude;

N_Sp - number of harmonic interference components used for its representation (approximation);

U_pi - amplitude of the i-th interference component;

K_sc, K_C - signal and interference conversion factors when squaring the sum of signal and interference.

The values of signal and interference conversion factors in squaring of the sum of signal and interference are determined experimentally at the stage of development of the means of communication.

Sources of interference include, for example, any radio transmitters, industrial interference caused by various electrical installations, and atmospheric interference. This interference affects the operation of radio receivers. Interference in modeling is presented as a set of harmonic oscillations with random values of amplitudes (U_pi) and phases (cp_Pi), which are distributed by normal (amplitude) and uniform (phase) laws (see, e.g. "Fundamentals of the theory of radio engineering systems”. Textbook. // V. I. Borisov, V. M. Zinchuk, A. E. Limarev, N. P. Mukhin. Edited by V.I. Borisov. Voronezh Research Institute of Communications, 2004, pp. 51, 68)

where: w_Rΐ, p_Pj - frequency and phase of the i-th interference component, respectively.

For an AWGN interference, the time of existence of the interference components is considered to be shorter than the time interval of sampling in the analog-to-digital converter (ADC), i.e. the interference samples are independent random values. A mixture of signal and interference at the receiver's linear path output is branched. In the compensation channel, signal processing is carried out in the same way as in the main channel, and the readings of signals that have passed the bandpass filter and LPF are taken with a time shift, the value of which is determined in advance.

The time shift value is set based on the condition of providing a given level of efficiency of the signals separation of different types at the stage of development by means of mathematical modeling or by experiment.

Signal samples that have passed the bandpass filter are subtracted from the signal readings that have passed the LPF. The obtained values are summed up and memorized. In this case, the voltage is equal to the sum of the squares of amplitudes of the interference components and signal amplitudes, changed to the value depending on the value of the time shift of sampling (see Fig. 1)

where: K_s - the value of change in the square of the signal amplitude, depending on the value of the time shift of signal sampling.

Denoting in equations (2) and (4)

we get a system of two equations with two unknowns

U = K_sc U² _s+ K _c P²,

U = K_s K U² _s+ K P². (6)

Solving this system of equations relative to U²s, we obtain

u eU -^K_sc -K_s K_sc). (7) Applying f. (7) calculate the signal amplitude value using the stored voltage values obtained in the main and compensation channels.

If the offset time of the signal samples in the compensation channel is set to T/4,

where T is the value of the frequency change period at which the processing is performed (see Fig. 1), in this case in the compensation channel

U² _S=0.

Then f. 7 can be written down as

U² s⁼ (Ui~U₂)/ Ksc· (8)

Conclusion about the presence of the first or second type signal is made by comparing the obtained value of the signal amplitude with the corresponding threshold.

The threshold value is determined, for example, by using a reference signal that is transmitted before the messages are sent.

The results of evaluation of the efficiency of the proposed method were obtained by the method of mathematical modeling on a computer using the MATLAB system.

The following input data were used in the modeling process:

- number of implementations - 10³;

- type of manipulation - amplitude manipulation;

- signal amplitude ratio (U1/U2) - 1.5;

- ratio of the upper frequency of the signal bandwidth to the lower frequency of the signal - 1.1;

- number of samples per period when estimating the power of the signal and interference mixture with the prototype method and the proposed method - 2;

- number of signal periods - 3;

- number of harmonic components of the interference used for its representation - 10³; - K_sc, 0.5;

- Ks, 0.2;

- probability of correct detection - 0.999;

- probability of a false alarm - 10 ³.

Modeling results for the AWGN type interference are given in the table.

The following symbols are used in the table:

K_s - suppression, ratio of the combination components of interference and signal and interference (%);

Q_pm - ratio of interference power to signal power for the proposed method;

Q_prm - ratio of interference power to signal strength for prototype method;

Qpm/Qprm - ratio of interference power to signal power for the proposed method and the prototype method.

Data analysis in the table allows to draw a conclusion that efficiency of the offered method practically does not concede efficiency of a prototype method under the influence of AWGN interference. At the rate of interference power change comparable with the value of the period of signal frequency change, the rate of information exchange when using the proposed method can be almost doubled, compared wit the case of the prototype method.

Thus, the use of the proposed method can increase the speed of information exchange due to the fact that the estimation of the power of interference and the sum of the signal and interference is carried out almost simultaneously. Brief drawings description

Graphical explanation of sampling in the main and compensation channels is shown in Fig. 1.

Block diagram of the device implementing the proposed method is shown in Fig. 2, where it is indicated:

1 - intermediate frequency amplifier (IF A);

2.1, 2.2, 2.3, 2.4, 2.5 - first to fifth splitters;

3.1, 3.2 - first and second multiplication units;

4.1, 4.2 - first and second lowpass filters (LPF);

5.1, 5.2, 5.3, 5.4 - first to fourth analog-to-digital converters (ADC);

6.1, 6.2 - first and second bandpass filters (BPF);

7 - computing device (CD).

The device contains a series of connected IFA 1, the first splitter 2.1, the second splitter 2.2, the first multiplication unit 3.1, the third splitter 2.3, the first LPF 4.1, the first ADC 5.1 and a computing device 7, the output of which is the device output, while the second output of the second splitter 2.2 is connected to the second input of the first multiplication unit 3.1. The second output of the third splitter 2.3 through a series of connected first BPF 6.1 and the second ADC 5.2 is connected to the second input of the computing device 7. The second output of the first splitter 2.1 through a series of connected fourth splitter 2.4, the second multiplication unit 3.2, the fifth splitter 2.5, the second LPF 4.2 and the third ADC 5.3 is connected to the third input of the computing device 7. The second output of the fourth splitter 2.4 is connected to the second input of the second multiplication unit 3.2. The second output of the fifth splitter 2.5 is connected in series with the second BPF and the fourth ADC 5.4 to the fourth input of the computing device 7. IFA input 1 is the device input. The first splitter input 2.1 is the main processing channel input. The outputs of the first 5.1 and second 5.2 ADC are respectively the first and second outputs of the main channel. The input of the fourth splitter 2.4 is the input of the compensation processing channel. Outputs of the third 5.3 and fourth 5.4 ADC are respectively the first and second outputs of the compensation channel.

Industrial applicability

The device works as follows.

Describes the method for fixed frequency operation. In case of frequency tuning, the process is carried out for each operating frequency as well as for a fixed frequency.

A harmonic signal is used. Type of manipulation - amplitude manipulation (AMn).

Two types of signal are formed. Signals of different types differ in amplitudes by a specified number of times f. (1).

It is believed that synchronization has been carried out at the time of communication, and the position in the start time of the signal is known with sufficient accuracy to take samples with the necessary accuracy.

Additive mixture of signal and interference is processed in the linear path of the receiver, after which it is fed from the output of IFA 1 to the first splitter 2.1, where a mixture of signal and interference is branched into two identical components. The first component is fed to the second splitter 2.2, where the mixture of signal and interference is branched into two identical components, which are fed to the first and second inputs of the first multiplication block 3.1, respectively. The result of squaring the signal and interference mixture (further on - a signal) is submitted on the third splitter 2.3 where it is branched on two identical components. The first component is filtered by the first LPF 4.1, the bandwidth of which is matched to the signal bandwidth. The second component is filtered by the first BPF 6.1 , the bandwidth of which is selected so that the upper frequency of the bandpass filter corresponds to the upper frequency of the signal, the lower frequency BPF 6.1 is selected as close to zero. The choice of the first 4.1 and second 4.2 LPF and the first 6.1 and second 6.2 bandpass filters shall be carried out with the maximum phase and frequency response identical to each other and in such a way that the sum of the differences in the LPF amplitude and bandpass characteristics taken for all frequencies is as small as possible. The signal from the output of the first LPF 4.1 is fed to the first analog-to-digital converter (ADC) 5.1. The signal from the first BPF 6.1 output is fed to the second ADC 5.2. In the first 5.1 and second 5.2 ADC they form the digital signal samples. The signal samples from the outputs of the first 5.1 and second 5.2 ADC is fed to the first and second inputs of CD 7, respectively, in which the signal passed to the output of the first LPF 4.1 is subtracted from the signal passed to the output of the first BPF 6.1. The obtained values are summed up and memorized.

In the compensation channel signal processing is carried out in the same way as in the main channel, with the signal samples that have passed the second LPF 4.2 and the second BPF 6.2, which are form in the third ADC 5.3 and the fourth ADC 5.4, respectively, are taken with a time shift, the value of which is determined in advance (see Fig. 1).

In CD 7 they calculate the difference between the signal samples that have passed the second LPF 4.2 and the readings of the signals that have passed the second BPF 6.2, these values are summed up and stored. They calculate the signal amplitude value using the stored voltage values obtained in the main and compensation channels using f. (7).

Conclusion about the presence of the first or second type signal is made by comparing the obtained value of the signal amplitude with the corresponding threshold. The threshold value is determined, for example, by using a reference signal that is transmitted before the messages are sent.

The simulation results are given in the corresponding description table.

IFA 1 can be implemented, for example, on an AD8054ARUZ chip from Analog Devices.

First 5.1 to fourth 5.4 ADC can be implemented, for example, on the ADS8422 chip by Texas Instruments.

Computer device 7 can be made in the form of a programmable logic integrated circuit (PLIC), and implemented, for example, on the XC2V3000- 6FG676I chip of Xilinx company.

Thus, when using the proposed method and the implementation device, the efficiency of the proposed method is almost as good as that of the prototype method under the conditions of AWGN interference. When the power of the interference is changed at a rate commensurate with the value of the period of change in the signal frequency, the speed of information exchange is almost doubled in comparison with the case of the prototype method, due to the fact that the assessment of the power of interference and signal is carried out at the same time.

Sources of information

RU 2675386 C2, 19.12.2018. Method and device for signal extraction in conditions of interference;

SU 1529148 Al, 15.12.1989. Method of measuring the signal-to-noise ratio and the device for its implementation;

RU 2608553 Cl, 23.01.2017. Method of allocating a signal under conditions of interference by compensating for interference by approximating its amplitude value; RU 2100903 Cl, 27.12.1997. Method of compensation of intra-channel additive radio interference in the receivers of amplitude-modulated, frequency and phase- manipulated radio signals and the device for its implementation.

Claims

The method of energy detection of the signal with compensation of the combinatorial components of the signal and interference in the main and compensation channels, consisting of fact that the additive mixture of signal and interference is processed in the linear path of the receiver, after which the mixture of signal and interference is squared, after squaring, the resulting signal is filtered by a lowpass filter (LPF), the band of which is consistent with the band signal; at the same time, the received signal is filtered by a bandpass filter, the bandwidth of which is selected so that the upper frequency of the bandpass filter corresponds to the upper frequency of the signal, the lower frequency of the bandpass filter is selected as close as possible to zero; the selection of LPF and bandpass filter is carried out with the maximum identical phase and frequency characteristics relative to each other and so that the minimum possible value of the sum of the differences in the LPF amplitude- frequency characteristics and the bandpass filter taken for all frequencies is provided; the samples of the signals passed through the bandpass filter and LPF are formed digitally in the corresponding analog-to- digital converters (ADC); these values are subtracted from one another in the computing device, the obtained values are summed and stored, characterized in that they use binary amplitude-modulated (AMn) signal, the amplitudes of various signals (of various types) differ by a specified number of times; the mixture of signal and interference at the output of the receiver linear path is branched, in the compensation channel, the processing of the signal and interference mixture is carried out as in the main channel, namely: the received signal is simultaneously filtered with processing in the main channel by the lowpass filter (LPF), the band of which is coordinated with the signal bandwidth; simultaneously, the received signal is filtered by a bandpass filter, formed digitally by converting it to the appropriate ADC, the signal samples that passed the bandpass filter and LPF, these values are subtracted from one another in the computing device, the received values are stored, and the readings of signals that passed the bandpass filter and LPF are taken with a time shift relative to the readings of the main channel, the value of which is determined in advance, the sum of the differences between the readings of the signals that have passed the bandpass filter and the readings of the signals that have passed the LPF, are memorized, they calculate the value of the signal amplitude using the memorized values of the voltages obtained mainly in the main and compensation channels, the conclusion about the presence of the signal of the first or second type is made based on result of comparing the obtained value of the signal amplitude with the corresponding threshold.