CN115097397A - Method and device for resisting intermittent sampling forwarding interference and electronic equipment - Google Patents
Method and device for resisting intermittent sampling forwarding interference and electronic equipment Download PDFInfo
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
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Abstract
The application relates to an anti-intermittent sampling forwarding interference method, an anti-intermittent sampling forwarding interference device and electronic equipment in the technical field of radar signal processing. The method is based on the idea of radar communication integration, and starts from the angle of identification-elimination interference suppression, firstly, chaotic coding and orthogonal multi-carrier modulation are carried out on radar signals at a transmitting end, and then target echo signals and intermittent sampling forwarding interference signals are decoded at a receiving end; and calculating the error rates of the target echo signal and the intermittent sampling forwarding interference signal, wherein the error rate of the interference signal is far greater than that of the target echo signal, and the interference is eliminated by setting an error rate threshold value so as to achieve the effect of interference suppression. The method has the advantages of simple anti-interference process, reduction of the error rate of radar communication under different environments, provision of a novel solution for the anti-interference problem of the radar communication integrated system, and provision of a new solution and a new thinking angle for solving the anti-interference problem in the radar field.
Description
Technical Field
The application relates to the technical field of radar signal processing, in particular to an anti-intermittent sampling forwarding interference method, an anti-intermittent sampling forwarding interference device and electronic equipment.
Background
With the rapid development of electronic technology, electronic combat environments are becoming more and more complex, which presents serious challenges for electronic reconnaissance and electronic countermeasure systems. Coded radar signals based on Orthogonal Frequency Division Multiplexing (OFDM) are a type of multi-carrier parallel modulated radar signals, and each path of sub-carriers are strictly Orthogonal, so that modulation and demodulation of signals are facilitated. The modulation information of each path of subcarrier can be different, so the design of the parameters has great flexibility and difficult predictability, and the method has strong anti-interference performance in specific application.
The intermittent Sampling and forwarding Interference (ISRJ) is a new type of coherent interference derived from a Digital Radio Frequency Memory (DRFM), and can provide both a compression mode and a deception mode effect by Sampling a radar transmission signal discontinuously and then performing corresponding modulation and forwarding. Coherent interference signals generated by the ISRJ technology have strong coherence with radar emission signals, so that larger pulse pressure gain can be obtained, and serious threat is formed to the survival capability of the radar.
In the existing research of integrated anti-ISRJ of radar communication, two common methods are adopted, wherein firstly, the anti-interference processing is carried out by utilizing the characteristic of discontinuous sampling of an interference signal time domain after the time-frequency domain analysis is carried out on a radar echo signal, and secondly, the waveform anti-interference design is adopted; although the two existing methods achieve certain achievements, the anti-interference process is complex, and the error rate of radar communication is high in different environments.
Disclosure of Invention
In view of the foregoing, it is necessary to provide an intermittent sampling forwarding interference resisting method, apparatus and electronic device.
A method of resisting intermittent sample forwarding interference, the method comprising:
and acquiring a receiving signal, wherein the receiving signal comprises a target echo signal and an intermittent sampling forwarding interference signal.
And synchronously demodulating the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal.
And obtaining the bit error rate of the target echo signal and the intermittent sampling forwarding interference signal according to the demodulated code element sequence and the original baseband sequence of the target echo signal and the intermittent sampling forwarding interference signal.
And performing interference identification according to the bit error rate of the target echo signal and the intermittent sampling forwarding interference signal and a preset bit error rate threshold value, and determining the intermittent sampling forwarding interference signal and the target echo signal.
And eliminating the intermittent sampling forwarding interference signals, and performing matched filtering on the target echo signals.
In one embodiment, the performing synchronous demodulation processing on the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal includes:
and carrying out carrier demodulation on the target echo signal and the intermittent sampling forwarding interference signal, and carrying out A/D conversion, cyclic prefix removal, serial-parallel conversion and FFT on a carrier demodulation result to obtain frequency domain signals of the target echo signal and the intermittent sampling forwarding interference signal.
And performing parallel/serial conversion on the frequency domain signals of the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal.
In one embodiment, the original baseband sequence is generated by a chaotic sequence.
Acquiring a received signal, wherein the steps comprise:
and performing serial-parallel conversion on the original baseband sequence generated by the transmitting end, and performing 16QAM (Quadrature amplitude modulation) coding mapping on the serial-parallel conversion result.
IFFT conversion is carried out on the mapped signals, parallel-serial conversion is carried out on the conversion results, and cyclic prefix and D/A conversion are added to the parallel-serial conversion results.
And modulating the obtained D/A conversion, and sending a modulation result through a Gaussian white noise channel.
In one embodiment, the obtained D/a conversion is modulated, and the modulation result is transmitted through a white gaussian noise channel, the radar signal transmitted through the white gaussian noise channel in the step is an OFDM radar signal, and the time domain expression thereof is:
in the formula, B k 、f k 、
Respectively complex input data, frequency and initial phase of the kth path of subcarrier of the OFDM radar signal; and N is the number of subcarriers.
In one embodiment, a receiving signal is obtained, and in the step of obtaining, a target echo signal in the receiving signal is:
wherein is located at a distance R 0 A is the target echo attenuation amplitude,
and c is the one-way propagation delay of the radar to the target, and the electromagnetic wave propagation speed.
The time domain expression of the intermittently sampled and forwarded interference signal in the received signal is as follows:
wherein S is j (t) is an intermittently sampled repeating interference signal, p (t) is an intermittently sampled rectangular envelope burst,
τ is the sampling pulse width, T S In order to be the sampling period of time,
is a duty cycle of the electric power,
representing a convolution operation, the function expression of rect (x) is S (t-t) j ) Is t j The radar signal at the time of day is,
is one-way propagation time delay from radar to jammer, N is intermittent sampling and forwarding times, N s The total number of retransmissions is intermittently sampled.
The expression of the received signal is:
S echo (t)＝S r (t)+S j (t)+n(t)
wherein n (t) is white Gaussian noise.
In one embodiment, obtaining the bit error rate of the target echo signal and the intermittent sampling forwarding interference signal according to the symbol sequence and the original baseband sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal includes:
determining the error code of the target echo signal in transmission according to the demodulated code element sequence and the original baseband sequence of the target echo signal, and obtaining the error code rate of the target echo signal according to the error code of the target echo signal in transmission and the total code number of the original baseband sequence; the calculation expression of the bit error rate of the target echo signal is as follows:
wherein, P r Representing target echo in transmissionThe error of the number, P, represents the total number of codes of the original baseband sequence transmitted.
And determining the error code of the intermittently sampled and forwarded interference signal in transmission according to the demodulated code element sequence and the original baseband sequence of the intermittently sampled and forwarded interference signal, and obtaining the error code rate of the intermittently sampled and forwarded interference signal according to the error code of the intermittently sampled and forwarded interference signal and the total code number of the original baseband sequence.
In one embodiment, the determining the intermittently sampled and forwarded interference signal and the target echo signal according to the bit error rates of the target echo signal and the intermittently sampled and forwarded interference signal and a preset bit error rate threshold includes:
and setting a preset error rate threshold value.
Respectively comparing the error rates of the target echo signal and the intermittent sampling forwarding interference signal with the preset error rate threshold, and judging the target echo signal and the intermittent sampling forwarding interference signal as the intermittent sampling forwarding interference signal when the error rate is greater than or equal to the preset error rate threshold; and when the error rate is less than a preset error rate threshold value, judging the target echo signal.
In one embodiment, the method further comprises:
and calculating the ratio of the target echo signal to the intermittent sampling forwarding interference signal according to the received target echo signal and the intermittent sampling forwarding interference signal.
And calculating the ratio of the target echo signal after matched filtering to the intermittent sampling forwarding interference signal according to the target echo signal after matched filtering and the intermittent sampling forwarding interference signal.
And evaluating the performance of the intermittent sampling forwarding interference resisting method according to the ratio of the signal to the interference and the difference value between the ratios of the target echo signal and the intermittent sampling forwarding interference signal after the matched filtering.
An intermittent sample-and-forward interference rejection apparatus, said apparatus comprising:
and the signal receiving module is used for acquiring a receiving signal, wherein the receiving signal comprises a target echo signal and an intermittent sampling forwarding interference signal.
And the signal demodulation module is used for synchronously demodulating the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal.
And the error rate calculation module is used for obtaining the error rate of the target echo signal and the intermittent sampling forwarding interference signal according to the demodulated code element sequence and the original baseband sequence of the target echo signal and the intermittent sampling forwarding interference signal.
And the interference identification module is used for identifying interference according to the error rate of the target echo signal and the intermittent sampling forwarding interference signal and a preset error rate threshold value, and determining the intermittent sampling forwarding interference signal and the target echo signal.
And the target echo signal determining module is used for eliminating the intermittent sampling forwarding interference signals and performing matched filtering on the target echo signals.
An electronic device comprising a memory and a processor, the memory storing a computer program, the processor implementing the steps of the method when executing the computer program.
The method is based on the idea of radar communication integration, and starts from the angle of identification-rejection interference suppression, firstly, chaos coding and orthogonal multi-carrier modulation are carried out on a radar signal at a transmitting end, and then, a target echo signal and an intermittent sampling forwarding interference signal are decoded at a receiving end; and calculating the error rates of the target echo signal and the intermittent sampling forwarding interference signal, wherein the error rate of the interference signal is far greater than that of the target echo signal, and the interference is eliminated by setting an error rate threshold value so as to achieve the effect of interference suppression. The method has a simple anti-interference process, reduces the error rate of radar communication under different environments, provides a novel solution for the anti-interference problem of a radar communication integrated system, and provides a new solution and a new thinking angle for solving the anti-interference problem in the field of radars.
Drawings
FIG. 1 is a schematic diagram of an embodiment of intermittent sample-and-forward interference;
FIG. 2 is a schematic flow chart of a method for resisting intermittent sampling forwarding interference in another embodiment;
FIG. 3 is a diagram illustrating the relationship between the bit error rate and the signal-to-noise ratio of a target echo signal and an intermittently sampled interference-forwarded signal in another embodiment;
FIG. 4 is a flow chart of interference identification and suppression based on integration of radar communication in another embodiment;
FIG. 5 is a block diagram of an OFDM modulation and demodulation process in another embodiment;
FIG. 6 is a diagram of the output of radar pulse pressure under anti-aliasing with intermittent sampling in another embodiment, where (a) is the output of pulse pressure before interference suppression and (b) is the output of pulse pressure after interference suppression;
FIG. 7 is a diagram of the output of radar pulse pressure under anti-oversampling forward interference in another embodiment, where (a) is the output of pulse pressure before interference suppression and (b) is the output of pulse pressure after interference suppression;
FIG. 8 shows interference discrimination at different SNR in another embodiment;
FIG. 9 is a comparison of the performance of different methods in another embodiment, where (a) is SJR-6 dB and (b) is SJR-9 dB;
FIG. 10 is a block diagram of an apparatus for anti-aliasing with intermittent sampling in one embodiment;
FIG. 11 is a diagram illustrating the internal architecture of an electronic device in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
The radar communication integration is a technology combining radar and communication, and aims to integrate the radar and the communication system on a platform in a certain scientific mode.
The intermittent sampling forwarding interference can be divided into intermittent sampling direct forwarding interference and intermittent sampling repeated forwarding interference according to different forwarding modes. The interference effect formed is different according to different forwarding modes. Intermittent Sampling and Direct Repeater Jamming (ISDRJ) means that after a small section of radar signal is sampled by a jammer, the current sampled signal is immediately retransmitted, and then the process is repeated until the radar pulse signal is finished. The intermittent Sampling and repetitive forwarding Interference (ISPRJ) means that after Sampling a small section of radar signal, an jammer repeatedly forwards the current Sampling signal until a specified number of times, then performs the next Sampling, and performs the same repetitive forwarding until the radar pulse signal is ended. An intermittent sample-and-forward interference schematic is shown in fig. 1.
In one embodiment, as shown in fig. 2, there is provided an intermittent sample forwarding interference resisting method, comprising the steps of:
step 200: and acquiring a receiving signal, wherein the receiving signal comprises a target echo signal and an intermittent sampling forwarding interference signal.
Step 202: and synchronously demodulating the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal.
Step 204: and obtaining the bit error rate of the target echo signal and the intermittent sampling forwarding interference signal according to the symbol sequence and the original baseband sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal.
Specifically, according to the principle of intermittently sampling the retransmission interference, whether the intermittent sampling direct retransmission interference or the intermittent sampling repeat retransmission interference is local sampling and retransmission of the transmission signal, the difference is mainly the difference of the retransmission times. As shown in fig. 1, in the case that the sampling duty ratio of the intermittent sampling forwarding interference is less than 1, regardless of the interference form, the intercepted sequence is always a part of the original sequence, and when the receiving end demodulates the intercepted sequence, the obtained demodulated sequence cannot restore the original baseband sequence, so that the concept of bit error rate is provided.
The error rate of the target echo signal is determined according to the error code generated by the transmission of the target echo signal on the interfered channel and the total code number of the original baseband sequence to be transmitted.
The error rate of the intermittently sampled retransmission interference signal is determined according to the error code generated by the transmission of the intermittently sampled retransmission interference signal on the interference channel and the total code number of the original baseband sequence to be transmitted.
Step 206: and carrying out interference identification according to the bit error rate of the target echo signal and the intermittent sampling forwarding interference signal and a preset bit error rate threshold value, and determining the intermittent sampling forwarding interference signal and the target echo signal.
Specifically, fig. 3 shows the bit error rates of the target echo signal and the intermittent sampling forwarding interference signal under the gaussian white noise channel. As can be seen from fig. 3, for the demodulation of the intermittent sampling retransmission interference Signal, the bit error rate is basically not affected by the Signal-to-noise Ratio (SNR), and is kept at a high position. For the demodulation of the target echo signal, the higher the signal-to-noise ratio is, the lower the bit error rate is. Therefore, the intermittent sampling forwarding interference signal and the target echo signal can be identified by setting the bit error rate threshold value, so that corresponding interference suppression is performed.
Step 208: and eliminating the intermittent sampling forwarding interference signals, and performing matched filtering on the target echo signals.
In the method for resisting intermittent sampling forwarding interference, based on the idea of radar communication integration, starting from the angle of identification-elimination interference suppression, the method firstly carries out chaotic coding and orthogonal multi-carrier modulation on a radar signal at a transmitting end, and then decodes a target echo signal and an intermittent sampling forwarding interference signal at a receiving end; and calculating the error rates of the target echo signal and the intermittent sampling forwarding interference signal, wherein the error rate of the interference signal is far greater than that of the target echo signal, and eliminating the interference by setting an error rate threshold value so as to achieve the effect of interference suppression. The method has the advantages of simple anti-interference process, reduction of the error rate of radar communication under different environments, provision of a novel solution for the anti-interference problem of the radar communication integrated system, and provision of a new solution and a new thinking angle for solving the anti-interference problem in the radar field.
In one embodiment, as shown in FIG. 4, step 202 comprises: carrying out carrier demodulation on the target echo signal and the intermittent sampling forwarding interference signal, and carrying out A/D conversion, cyclic prefix removal, serial-parallel conversion and FFT on the carrier demodulation result to obtain frequency domain signals of the target echo signal and the intermittent sampling forwarding interference signal; and performing parallel/serial conversion on the frequency domain signals of the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal.
In one embodiment, the original baseband sequence is generated by a chaotic sequence; step 200 is preceded by: performing serial-parallel conversion on an original baseband sequence generated by a transmitting end, and performing 16QAM (Quadrature amplitude modulation) coding mapping on a serial-parallel conversion result; performing IFFT transformation on the mapped signals, performing parallel-to-serial transformation on the transformation results, and adding cyclic prefix and D/A transformation to the parallel-to-serial transformation results; and modulating the obtained D/A conversion, and sending a modulation result through a Gaussian white noise channel.
Specifically, as shown in fig. 5, in a specific application, in order to increase the processing speed of the OFDM system, a Fast Fourier Transform (FFT) and an Inverse Fast Fourier Transform (IFFT) are usually adopted to implement modulation and demodulation of the OFDM signal. In the OFDM system, a generated baseband sequence is first subjected to serial-to-parallel conversion, so as to realize demultiplexing of a data stream, and a serial data stream is converted into a parallel data stream and then subjected to coding mapping. And performing IFFT transformation and parallel-serial transformation on the mapped signals to convert the frequency domain signals into time domain signals. In order to reduce the intersymbol interference and the intercarrier interference, a Cyclic Prefix (CP) is added, and finally the CP is transmitted through beamforming. At a receiving end, after analog-to-digital (A/D) conversion, CP removal, serial-to-parallel conversion and FFT, a received signal is converted from a time domain to a frequency domain, and finally, a demodulated sequence can be obtained after 16QAM demodulation and parallel-to-serial conversion.
In one embodiment, the obtained D/a conversion is modulated, and the modulation result is transmitted through a white gaussian noise channel, the radar signal transmitted through the white gaussian noise channel in the step is an OFDM radar signal, and the time domain expression thereof is:
in the formula, B k 、f k 、
Respectively complex input data, frequency and initial phase of the kth path of subcarrier of the OFDM radar signal; and N is the number of subcarriers.
In one embodiment, the target echo signal in the received signal in step 200 is:
wherein is located at a distance R 0 A is the target echo attenuation amplitude,
and c is the one-way propagation delay of the radar to the target, and the electromagnetic wave propagation speed.
When the distance between the jammer and the radar is R j And then, the time domain expression of the intermittent sampling forwarding interference signal is as follows:
wherein S is j (t) is an intermittently sampled forwarded interference signal, p (t) is an intermittently sampled rectangular envelope burst,
τ is the sampling pulse width, T S In order to be the sampling period of time,
is a duty cycle that is a function of,
representing a convolution operation, the function expression of rect (x) is S (t-t) j ) Is t j The radar signal at the time of day is,
is one-way propagation time delay from radar to jammer, N is intermittent sampling and forwarding times, N s The total number of retransmissions is intermittently sampled. The functional expression of rect (x) is:
the received signal is expressed as:
S echo (t)＝S r (t)+S j (t)+n(t) (4)
wherein n (t) is white Gaussian noise.
Specifically, the target and the jammer are usually located at different positions, and the pulse signals returned by the target and the jammer have different propagation delays. Therefore, for equation (4), the radar reception signal is actually a superposition of the target echo signal and the intermittently sampled retransmission interference signal in different time periods. Therefore, each received pulse signal can be decoded at the receiving end to obtain a decoded pulse sequence, and then the error rate is calculated, and then the interference identification and suppression are carried out.
In one embodiment, step 204 comprises: determining the error code of the target echo signal in transmission according to the demodulated code element sequence and the original baseband sequence of the target echo signal, and obtaining the error code rate of the target echo signal according to the error code of the target echo signal in transmission and the total code number of the original baseband sequence; the calculation expression of the bit error rate of the target echo signal is as follows:
wherein, P r Representing the error of the target echo signal in transmission, and P representing the total number of codes of the original baseband sequence in transmission.
And determining the error code of the intermittently sampled and forwarded interference signal in transmission according to the demodulated code element sequence and the original baseband sequence of the intermittently sampled and forwarded interference signal, and obtaining the error code rate of the intermittently sampled and forwarded interference signal according to the error code of the intermittently sampled and forwarded interference signal and the total code number of the original baseband sequence.
In one embodiment, step 206 comprises: and setting a preset error rate threshold value.
Respectively comparing the error rates of the target echo signal and the intermittent sampling forwarding interference signal with a preset error rate threshold, and judging the target echo signal and the intermittent sampling forwarding interference signal as the intermittent sampling forwarding interference signal when the error rate is greater than or equal to the preset error rate threshold; and when the error rate is less than a preset error rate threshold value, judging the target echo signal.
In one embodiment, the method further comprises: calculating the ratio of the target echo signal to the intermittent sampling forwarding interference signal according to the received target echo signal and the intermittent sampling forwarding interference signal; calculating the ratio of the target echo signal after matched filtering to the intermittent sampling forwarding interference signal according to the target echo signal after matched filtering and the intermittent sampling forwarding interference signal; and evaluating the performance of the method for resisting the intermittent sampling forwarding interference according to the ratio of the signal to the interference and the difference value between the ratios of the target echo signal and the intermittent sampling forwarding interference signal after the matched filtering.
Specifically, in order to evaluate the performance of resisting the intermittent sampling forwarding interference, a signal-to-interference ratio improvement factor is introduced, and the expression is as follows:
σ SJR ＝SJR PC -SJR (6)
wherein, SJR is the ratio of the target echo signal power to the intermittent sampling retransmission interference signal power, SJR PC Is the SJR value after match filtering.
It should be understood that, although the steps in the flowchart of fig. 2 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not limited to be performed in the exact order provided for in the present invention, and may be performed in other orders unless explicitly stated. Moreover, at least a portion of the steps in fig. 2 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.
In a verification embodiment, an anti-ISRJ interference experiment, an interference recognition rate experiment and an interference suppression performance evaluation are respectively performed, and a specific experimental process and analysis are as follows.
(1) anti-ISRJ interference experiments and analysis
The present embodiment employs a chaotic sequence having good characteristics to generate an original baseband sequence. The effectiveness of the interference suppression method is verified through a simulation experiment on radar pulse pressure output. The bandwidth of an OFDM radar transmitting signal is 4MHz, the carrier frequency is 12GHz, and the number of subcarriers is 2048. And setting the sampling width of the jammer to 1/3 of the width of the radar transmission signal, and setting the repeated forwarding times of the intermittent sampling to be 2. Under the scene that the SNR is 10dB and the SJR is-3 dB, the bit error rate threshold value is set to be 0.1, the obtained bit error rate result is shown in table 1, and the pulse pressure output before and after interference suppression is shown in figures 6 and 7.
TABLE 1 error Rate after decoding of signals under different interference patterns
As can be seen from table 1, the error rate of the decoded interference fragment is substantially close to 50%, the error rate is very large, the error rate of the target echo signal is substantially below 10%, the error rate difference between the two is large, and the interference forwarding fragment and the target echo signal can be distinguished by the difference of the error rates.
As can be seen from (a) in fig. 6, before interference suppression, the intermittent sampling direct forwarding interference forms a delayed realistic decoy at the radar pulse pressure output end, and the normalized decibel value is-5.53 dB; fig. 6(b) shows that the pulse pressure output after the interference suppression can better eliminate the interference, the target signal can be obviously detected, the normalized decibel value of the false target is reduced to-13.637 dB, and the improvement factor is 8.107 dB. Therefore, the ISRJ resisting method provided by the invention can effectively inhibit intermittent sampling direct forwarding interference.
As shown in fig. 6, which is a simulation experiment against ISPRJ, it can be known from fig. 6(a) that, before interference suppression, ISPRJ can make an OFDM radar generate a plurality of realistic false targets, increasing difficulty in target detection; and fig. 6(b) can obviously reduce the amplitude of the false target signal after using the method provided by the invention, thereby extracting the real target. Therefore, the method can effectively inhibit the intermittent sampling repeat forwarding interference.
(2) Interference recognition rate experiment and analysis
The ISRJ resisting method designed by the invention needs to demodulate the received signal, so the interference identification and suppression effect depends on the demodulated error rate, the demodulated error rate is related to the signal-to-noise ratio, different signal-to-noise ratios have certain influence on the identification of the intermittent sampling forwarding interference signal, and the experiment for setting the interference identification rate is as follows: in order to explore the recognition rate condition of the method under a lower signal-to-noise ratio, the threshold value of the error rate is properly adjusted to be 0.25; for different SNR values, the method for identifying the interference is carried out according to the ISRJ resisting method provided by the invention, and the corresponding interference identification rate is counted, wherein the Monte Carlo experiment times are 500. The relationship graph of the obtained interference discrimination is shown in fig. 8, and can be obtained from the graph: when the SNR reaches 2dB, the interference identification rate approaches to 90%, and the interference identification rate approaches to 100% along with the increase of the SNR, which shows that the method provided by the invention has better stability and effectiveness.
(3) Interference suppression performance assessment
The set-up experiment was as follows: for different signal-to-noise ratio (SNR) values, let the input signal-to-interference ratio (SJR) be-6 dB and-9 dB, measure the pulse pressure output after interference suppression, and calculate the SJR improvement factor curve graph as shown in fig. 9, where the number of monte carlo experiments is 500.
As can be seen from fig. 9, the suppression effect of the method proposed by the present invention is significantly better than the method of designing a CC-MCPC signal resistant to intermittent sampling interference from the perspective of waveform design, and is also better than a novel Repetitive Linear Redundancy (RLR) waveform based on Multiple Input Multiple Output (MIMO) radar and multi-carrier phase code (MCPC) radar signals, and the lower the SJR value input by the matched filter is, the more significant the method used by the present invention is, because the method can remove interference from the received signal, and the two anti-interference methods only suppress interference without completely removing interference, so that the SJR improvement factor is not significantly increased when the SJR input by the matched filter is reduced. Of course, the method does not conflict with the methods used by the two methods, and the two methods may be used in combination.
The method for resisting the intermittent sampling forwarding interference based on the radar communication integrated information processing aims at the characteristic that the intermittent sampling is only to locally sample and forward an original signal, and resists the intermittent sampling forwarding interference from the angle of modulation and demodulation. Simulation results show that the method provided by the invention can effectively inhibit interference signals no matter resisting intermittent sampling direct forwarding interference or intermittent sampling repeated forwarding interference. And the method is not in conflict with the waveform design anti-interference method and can be used simultaneously. The method for resisting the system interference by utilizing the radar communication integration is a novel approach for solving the problem of interference resistance, and provides a new solution and a new thinking angle for solving the problem of interference resistance in the field of radars.
In one embodiment, as shown in fig. 10, there is provided an anti-intermittent sample forwarding interference apparatus, including: signal reception module, signal demodulation module, bit error rate calculation module, interference identification module and target echo signal determine module, wherein:
and the signal receiving module is used for acquiring a receiving signal, wherein the receiving signal comprises a target echo signal and an intermittent sampling forwarding interference signal.
And the signal demodulation module is used for synchronously demodulating the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal.
And the error rate calculation module is used for obtaining the error rate of the target echo signal and the intermittent sampling forwarding interference signal according to the demodulated code element sequence and the original baseband sequence of the target echo signal and the intermittent sampling forwarding interference signal.
And the interference identification module is used for identifying interference according to the error rate of the target echo signal and the intermittent sampling forwarding interference signal and a preset error rate threshold value, and determining the intermittent sampling forwarding interference signal and the target echo signal.
And the target echo signal determining module is used for eliminating the intermittent sampling forwarding interference signals and performing matched filtering on the target echo signals.
In one embodiment, the signal demodulation module is further configured to perform carrier demodulation on the target echo signal and the intermittent sampling forwarding interference signal, and perform a/D conversion, cyclic prefix removal, serial-to-parallel conversion, and FFT on a carrier demodulation result to obtain frequency domain signals of the target echo signal and the intermittent sampling forwarding interference signal; and performing parallel/serial conversion on the frequency domain signals of the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal.
In one embodiment, the original baseband sequence is generated by a chaotic sequence; the signal receiving module also comprises a radar signal transmitting module used for carrying out serial-parallel conversion on the original baseband sequence generated by the transmitting end and carrying out 16QAM coding mapping on the serial-parallel conversion result; performing IFFT transformation on the mapped signals, performing parallel-serial transformation on the transformation result, and adding cyclic prefix and D/A transformation to the parallel-serial transformation result; and modulating the obtained D/A conversion, and sending a modulation result through a Gaussian white noise channel.
In one embodiment, the radar signal transmitted by the radar signal transmitting module through the gaussian white noise channel is an OFDM radar signal, and the time domain expression thereof is as shown in formula (1).
In one embodiment, the target echo signal in the received signal in the signal receiving module is shown as equation (2).
The time domain expression of the intermittently sampled and forwarded interference signal in the received signal is shown in formula (3).
The received signal expression is shown in equation (4).
In one embodiment, the bit error rate calculation module is further configured to determine an error code of the target echo signal during transmission according to the symbol sequence of the demodulated target echo signal and the original baseband sequence, and obtain the bit error rate of the target echo signal according to the error code of the target echo signal during transmission and the total code number of the original baseband sequence; the calculation expression of the bit error rate of the target echo signal is shown in formula (5).
And determining the error code of the intermittently sampled and forwarded interference signal in transmission according to the demodulated code element sequence and the original baseband sequence of the intermittently sampled and forwarded interference signal, and obtaining the error code rate of the intermittently sampled and forwarded interference signal according to the error code of the intermittently sampled and forwarded interference signal and the total code number of the original baseband sequence.
In one embodiment, the interference identification module is further configured to set a preset bit error rate threshold; respectively comparing the error rates of the target echo signal and the intermittent sampling forwarding interference signal with a preset error rate threshold, and judging the target echo signal and the intermittent sampling forwarding interference signal as the intermittent sampling forwarding interference signal when the error rate is greater than or equal to the preset error rate threshold; and when the error rate is less than a preset error rate threshold value, judging the target echo signal.
In one embodiment, the method further comprises a performance evaluation module, configured to calculate a ratio of a target echo signal to an intermittently sampled forwarding interference signal according to the received target echo signal and the intermittently sampled forwarding interference signal; calculating the ratio of the target echo signal after matched filtering to the intermittent sampling forwarding interference signal according to the target echo signal after matched filtering and the intermittent sampling forwarding interference signal; and evaluating the performance of the method for resisting the intermittent sampling forwarding interference according to the ratio of the signal to the interference and the difference value between the ratios of the target echo signal and the intermittent sampling forwarding interference signal after the matched filtering.
The specific definition of the apparatus for resisting intermittent sampling forward interference can be referred to the definition of the method for resisting intermittent sampling forward interference, and is not described in detail here. The modules in the above-mentioned anti-intermittent sampling forwarding jamming device can be wholly or partially implemented by software, hardware and their combination. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as shown in fig. 11. The computer device includes a processor, a memory, a network interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a method of anti-aliasing against intermittent samples. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on a shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.
It will be appreciated by those skilled in the art that the configuration shown in fig. 11 is a block diagram of only a portion of the configuration associated with the present application, and is not intended to limit the computing device to which the present application may be applied, and that a particular computing device may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.
In an embodiment, an electronic device is provided, comprising a memory storing a computer program and a processor implementing the steps of the above method embodiments when the processor executes the computer program.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, and these are all within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for resisting intermittent sampling forwarding interference, the method comprising:
acquiring a receiving signal, wherein the receiving signal comprises a target echo signal and an intermittent sampling forwarding interference signal;
synchronously demodulating the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the demodulated intermittent sampling forwarding interference signal;
obtaining the bit error rate of the target echo signal and the intermittent sampling forwarding interference signal according to the demodulated code element sequence and the original baseband sequence of the target echo signal and the intermittent sampling forwarding interference signal;
performing interference identification according to the error rate of the target echo signal and the intermittent sampling forwarding interference signal and a preset error rate threshold value, and determining the intermittent sampling forwarding interference signal and the target echo signal;
and eliminating the intermittent sampling forwarding interference signals, and performing matched filtering on the target echo signals.
2. The method of claim 1, wherein performing synchronous demodulation processing on the target echo signal and the intermittently sampled retransmission interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittently sampled retransmission interference signal comprises:
carrying out carrier demodulation on the target echo signal and the intermittent sampling forwarding interference signal, and carrying out A/D conversion, cyclic prefix removal, serial-parallel conversion and FFT on a carrier demodulation result to obtain frequency domain signals of the target echo signal and the intermittent sampling forwarding interference signal;
and performing parallel/serial conversion on the frequency domain signals of the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal.
3. The method of claim 1, wherein the original baseband sequence is generated by a chaotic sequence;
acquiring a received signal, wherein the steps comprise:
performing serial-parallel conversion on an original baseband sequence generated by a transmitting end, and performing 16QAM (Quadrature amplitude modulation) coding mapping on a serial-parallel conversion result;
performing IFFT transformation on the mapped signals, performing parallel-to-serial transformation on the transformation results, and adding cyclic prefix and D/A transformation to the parallel-to-serial transformation results;
and modulating the obtained D/A conversion, and sending a modulation result through a Gaussian white noise channel.
4. The method according to claim 3, wherein the obtained D/A conversion is modulated, and the modulation result is transmitted through a Gaussian white noise channel, and the radar signal transmitted through the Gaussian white noise channel in the step is an OFDM radar signal, and the time domain expression is as follows:
in the formula, B k 、f k 、
Respectively complex input data, frequency and initial phase of the kth path of subcarrier of the OFDM radar signal; and N is the number of subcarriers.
5. The method of claim 4, wherein the received signals are obtained, and the target echo signals in the received signals in the step are:
wherein is located at a distance R 0 A is the target echo attenuation amplitude,
c is the one-way propagation time delay of the radar to the target, and c is the propagation speed of the electromagnetic wave;
the time domain expression of the intermittently sampled and forwarded interference signal in the received signal is as follows:
wherein S is j (t) is an intermittently sampled repeating interference signal, p (t) is an intermittently sampled rectangular envelope burst,
τ is the sampling pulse width, T S In order to be the sampling period of time,
is a duty cycle that is a function of,
representing a convolution operation, the function expression of rect (x) is S (t-t) j ) Is t j The radar signal at the time of day is,
is one-way propagation time delay from radar to jammer, N is intermittent sampling and forwarding times, N s The total number of intermittent sampling and forwarding times;
the expression of the received signal is:
S echo (t)＝S r (t)+S j (t)+n(t)
wherein n (t) is white Gaussian noise.
6. The method of claim 1, wherein obtaining the bit error rates of the target echo signal and the intermittently sampled retransmission interference signal according to the symbol sequence and the original baseband sequence of the demodulated target echo signal and the intermittently sampled retransmission interference signal comprises:
determining the error code of the target echo signal in transmission according to the demodulated code element sequence and the original baseband sequence of the target echo signal, and obtaining the error code rate of the target echo signal according to the error code of the target echo signal in transmission and the total code number of the original baseband sequence; the calculation expression of the bit error rate of the target echo signal is as follows:
wherein, P r Representing the error of the target echo signal in transmission, and P representing the total number of codes of the original baseband sequence in transmission.
And determining the error code of the intermittently sampled and forwarded interference signal in transmission according to the demodulated code element sequence and the original baseband sequence of the intermittently sampled and forwarded interference signal, and obtaining the error code rate of the intermittently sampled and forwarded interference signal according to the error code of the intermittently sampled and forwarded interference signal and the total code number of the original baseband sequence.
7. The method of claim 1, wherein the determining the intermittently sampled re-transmission interference signal and the target echo signal according to the bit error rate of the target echo signal and the intermittently sampled re-transmission interference signal and a predetermined bit error rate threshold comprises:
setting a preset error rate threshold value;
respectively comparing the error rates of the target echo signal and the intermittent sampling forwarding interference signal with the preset error rate threshold, and judging the target echo signal and the intermittent sampling forwarding interference signal as the intermittent sampling forwarding interference signal when the error rate is greater than or equal to the preset error rate threshold; and when the error rate is less than a preset error rate threshold value, judging the target echo signal.
8. The method according to any one of claims 1-7, further comprising:
calculating the ratio of the target echo signal to the intermittent sampling forwarding interference signal according to the received target echo signal and the intermittent sampling forwarding interference signal;
calculating the ratio of the target echo signal after matched filtering to the intermittent sampling forwarding interference signal according to the target echo signal after matched filtering and the intermittent sampling forwarding interference signal;
and evaluating the performance of the intermittent sampling forwarding interference resisting method according to the ratio of the signal to the interference and the difference value between the ratios of the target echo signal and the intermittent sampling forwarding interference signal after the matched filtering.
9. An apparatus for resisting intermittent sample-and-forward interference, the apparatus comprising:
the signal receiving module is used for acquiring a receiving signal, wherein the receiving signal comprises a target echo signal and an intermittent sampling forwarding interference signal;
the signal demodulation module is used for synchronously demodulating the target echo signal and the intermittent sampling forwarding interference signal to obtain a symbol sequence of the demodulated target echo signal and the intermittent sampling forwarding interference signal;
the error rate calculation module is used for obtaining the error rate of the target echo signal and the intermittent sampling forwarding interference signal according to the demodulated code element sequence and the original baseband sequence of the target echo signal and the intermittent sampling forwarding interference signal;
the interference identification module is used for carrying out interference identification according to the error rate of the target echo signal and the intermittent sampling forwarding interference signal and a preset error rate threshold value, and determining the intermittent sampling forwarding interference signal and the target echo signal;
and the target echo signal determining module is used for eliminating the intermittent sampling forwarding interference signals and carrying out matched filtering on the target echo signals.
10. An electronic device comprising a memory and a processor, the memory storing a computer program, wherein the processor implements the steps of the method of any one of claims 1 to 8 when executing the computer program.
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| CN116609732B (en) * | 2023-07-21 | 2023-12-08 | 江西红声技术有限公司 | Anti-intermittent sampling forwarding interference radar method, system, storage medium and computer |
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