Novel suppressing interference mode analysis and identification method

Abstract

The invention relates to the technical field of electromagnetic environment signal monitoring, in particular to a novel suppressing interference mode analysis and identification method, which comprises the following steps of: sending a leading signal before each pulse during radar scanning, and acquiring frequency spectrum and envelope data from the current leading signal time period to the next leading signal time period in real time by an interception device; the processing front end carries out digital channelization processing and accumulation on the spectrum data, carries out sliding window recording on envelope data, and carries out timed framing transmission to the processing rear end; the processing rear end carries out conjoint analysis on the collected frequency spectrum and envelope information, and if interference exists, the interference is recorded in a temporary interference result table; when the radar continuously rotates for 5 degrees and no interference is detected, extracting all data between the starting index and the cut-off index, determining the real orientation of an interference source through the maximum amplitude point of an interference signal, and analyzing the broadband or narrowband, sweep frequency or non-sweep frequency and continuous or discontinuous characteristics of the interference source; and finally, outputting a result according to a characteristic judgment criterion and emptying the temporary table for circular detection.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic environment signal monitoring, and particularly to a new method for analyzing and identifying jamming patterns, which is applicable to electronic reconnaissance equipment to achieve accurate identification and analysis of jamming signals. Background Art

[0002] Jamming is a common means in electronic countermeasures. It mainly covers the target echo by transmitting high-power noise or noise-like signals, seriously interfering with the detection and parameter estimation of targets by radar. In the prior art, conventional anti-jamming methods are difficult to effectively deal with different types of jamming. The main reason is the lack of accurate identification of jamming patterns. For example, broadband jamming requires the use of spectrum spreading technology, and swept-frequency jamming requires dynamic frequency tracking. However, existing methods mostly rely on single amplitude or frequency range characteristics for judgment, which is prone to misjudgment or missed detection. In addition, there are asynchronous problems in data acquisition and analysis in traditional technologies, making it difficult to capture the dynamic changes of jamming signals in real time. Therefore, it is necessary to develop a method for analyzing and identifying jamming patterns to improve the pertinence and effectiveness of anti-jamming measures. Summary of the Invention

[0003] To solve some problems existing in the above prior art, the present invention provides a new method for analyzing and identifying jamming patterns. This method can efficiently identify characteristics such as broadband or narrowband, swept-frequency or non-swept-frequency, continuous or discontinuous of jamming by transmitting a leading signal during the radar scanning process and using a receiving device to collect spectrum and envelope data between the current and the next leading signal in real time, combined with dynamic temporary table management and multi-dimensional feature analysis, providing a reliable basis for anti-jamming measures.

[0004] To achieve the above object, the present invention provides a new method for analyzing and identifying jamming patterns, and the method includes the following steps: Step 1: During the radar scanning process, before each pulse is transmitted, a leading signal is sent to the supporting receiving device. The leading signal includes information such as the transmission time, center frequency, bandwidth, signal form, azimuth, pulse width, and frame synchronization code of the next pulse; Step 2: The receiving device collects spectrum and envelope data between the current and the next leading signal in real time according to the received leading signal; Step 3: The processing front end performs digital channelization processing and accumulation on the spectrum data, and at the same time performs sliding window recording on the envelope data. The sliding window interval is 256 ns, and it is regularly framed and transmitted to the processing back end; where framing means, according to the message protocol, with a fixed frame length, excluding the message head and tail and leading synchronization information, calculating the number of envelope information that can be stored in the remaining space; if a preset number of envelope information is sent in one frame, the timing duration is the preset number multiplied by the time interval, and one frame is output; Step 4: The backend processes the jointly analyzes and stores the collected spectrum and envelope information to determine whether there is an interference signal. If there is an interference signal, it is recorded in the temporary interference result table and the starting index is recorded. When the interference signal is detected for the first time, the recording of the temporary interference result table is started. The determination of whether there is an interference signal specifically includes: First, it is determined whether there is a signal within the cooperative radar frequency bandwidth. If there is, it is preliminarily judged as having an interference signal and recorded in the temporary interference result table. Second, if there is a signal within 5 times the cooperative radar frequency bandwidth but not within the cooperative radar frequency bandwidth, it is preliminarily judged as having an interference signal, the sweep frequency mode flag is set, and it is recorded in the temporary interference result table at the same time. If neither of the above two situations is satisfied, it is preliminarily judged as having no interference signal. The management strategy of the temporary interference result table includes: creating a temporary table when the interference is detected for the first time and recording the starting index. When the radar azimuth rotates continuously by 5° and no more interference signals are received, the most recently received interference is used as the cut-off index and the mode analysis is triggered. When analyzing, first find the maximum instantaneous amplitude, and use the instantaneous azimuth and instantaneous amplitude at this moment as the azimuth and amplitude of the interference source. Statistically calculate the maximum and minimum values of all instantaneous center frequencies, calculate the difference as the frequency bandwidth of the interference source, and use the central value as the center frequency of the interference source, and then determine the interference mode. The joint analysis of the spectrum and envelope information includes: spectrum analysis is used to determine the interference frequency range and amplitude distribution, and envelope analysis is used to detect the signal continuity and phase characteristics. By comparing the spectrum data of adjacent frames, the frequency hopping law of the sweep frequency interference is identified. By combining the azimuth information, a spatial distribution map of the interference source is established. Step 5: When the radar rotates continuously by 5° without detecting interference, the last interference record is used as the cut-off index, and then all the spectrum and envelope data between the starting index and the cut-off index are extracted. The true azimuth of the interference source is determined through the maximum amplitude point of the interference signal, and its broadband or narrowband, sweep frequency or non-sweep frequency, and continuous or discontinuous characteristics are analyzed. The analysis of the azimuth and characteristics of the interference source includes: First, traverse the temporary interference result table, extract the instantaneous amplitudes of all interference records, and use the azimuth corresponding to the maximum value as the true azimuth of the interference source. Then, statistically calculate the maximum and minimum values of all instantaneous center frequencies, and calculate the difference as the bandwidth of the interference signal. If the bandwidth is greater than 5 times the cooperative radar bandwidth, it is determined as broadband suppression interference. If the bandwidth is between 2 and 5 times, it is determined as narrowband suppression interference. If the instantaneous center frequency of the interference signal is not fixed and changes regularly such as linearly or at equal intervals, it is determined as sweep frequency, otherwise it is determined as non-sweep frequency interference. If the envelope of the interference signal has a breakpoint and the breakpoint duration exceeds 1 ms, it is determined as discontinuous interference, otherwise it is continuous interference. Step 6: Output the recognition result according to the interference characteristic determination criterion, and clear the temporary interference result table to loop and perform subsequent detections.

[0005] The beneficial effects of the present invention are as follows: By comprehensively utilizing spectrum and envelope information for joint analysis, it can comprehensively and accurately describe the characteristics of interference signals, overcome the limitations of single-characteristic analysis, and improve the accuracy of interference recognition; By using the leading signal of the radar to synchronize the receiving device with the radar, it can collect and process interference signals in real time, respond in a timely manner to changes in interference signals, and meet the real-time requirements of modern electronic warfare; It can accurately identify characteristics such as broadband or narrowband, frequency sweeping or non-frequency sweeping, and continuous or intermittent of interference, providing detailed and accurate basis for anti-interference decision-making of electronic devices, and helping to take targeted anti-interference measures; It uses a temporary interference result table to manage interference data, determines the start index and end index in combination with radar azimuth information, avoids redundant recording of data, and improves data processing efficiency.

[0006] When the present invention works, when the radar is scanning, before each pulse is transmitted, it will send a leading signal containing detailed information of the next pulse to the supporting receiving device; The receiving device, according to the received leading signal, collects the spectrum and envelope data between the current time and the next leading signal in real time; The processing front end performs digital channelization processing and accumulation on the spectrum data, and at the same time performs sliding window recording on the envelope data and periodically groups and transmits it to the processing back end; The processing back end performs joint analysis on the collected spectrum and envelope information to determine whether there is an interference signal. If there is, it is recorded in the temporary interference result table; When the radar rotates continuously by 5° without detecting interference, all data between the start and end indexes are extracted, the true azimuth of the interference source is determined through the maximum amplitude point of the interference signal, and its broadband or narrowband, frequency sweeping or non-frequency sweeping, and continuous or intermittent characteristics are analyzed; Finally, according to the interference characteristic determination criterion, the recognition result is output, and the temporary interference result table is cleared to cycle and perform subsequent detections. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] For the convenience of those skilled in the art to understand, the present invention will be further described below in conjunction with the drawings: Figure 1 It is the flowchart of the interference signal pattern analysis of the present invention.

[0008] Figure 2 It is a frame of spectrogram in the embodiment of the present invention.

[0009] Figure 3 It is the complete envelope diagram of an interference signal received in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] In order to enable those skilled in the art to better understand the technical solutions in this application, the present invention will be further described below in conjunction with the drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0011] This embodiment is used for a reconnaissance receiver, and its main related functions are as follows: 1. It has the function of direction finding of interference sources: for continuous wave noise interference, it has the function of gating and recording the direction of interference sources. The number of interference source direction lines that can be formed per circle is not less than 20. The interference source direction lines contain time stamps, azimuth information, and interference intensity values, and can perform statistical analysis; 2. It has the function of analyzing interference modes: that is, it can distinguish characteristics such as broadband, narrowband, frequency sweeping, continuous, and discontinuous; The solution adopted to achieve the above functions is the technical solution described in the present invention; A novel method for analyzing and identifying suppression interference modes described in the present invention, as shown in the appendix Figure 1 is used for the receiving and processing unit of a reconnaissance receiver and is implemented by software. The hardware platform of the receiving and processing unit is a PSOC, and FMQL45T900 of Fudan Microelectronics is selected. The single chip integrates a processing system (PS) based on a quad-core processor and programmable logic (PL). The software of this method is implemented by the cooperation of PL and PS.

[0012] As the processing front end, PL receives the AD acquisition data, completes the digital channelization function, accumulates spectrum and envelope data, and at the same time receives the leading information from the radar. For each received leading information, it switches the spectrum frame of the previous leading to PS, and at the same time records the signal envelope for each sliding window, forms a fixed-length envelope frame according to the message protocol, and switches it to PS; As the processing back end, PS receives the spectrum and envelope from PL, and analyzes and processes them according to the method described in the present invention to find the azimuth of the interference source and its interference mode; The data interaction between PL and PS is carried out through a shared BRAM. The data interface form is a message, and the switching method is an interrupt. The message synchronization is based on the leading information.

[0013] The specific implementation method and steps are as follows: Step 1: The processing front end receives the leading information and sends the spectrum of the previous leading information to the processing back end; then starts a new spectrum accumulation according to the synchronization moment of the current leading signal information; the leading information in this embodiment includes information such as the emission time, center frequency, bandwidth, signal form, azimuth, pulse width, and frame synchronization code of the cooperative radar in the next pulse; the spectrum, its message carries the leading information of the cooperative radar; the spectrum accumulation is carried out based on digital channelization processing; Step 2: Meanwhile, process the envelope information recorded by each sliding window at the front end and frame it at regular intervals and send it to the processing backend; the framing means, according to the message protocol, with a fixed frame length, removing the message head, tail and preamble synchronization information, calculating the number of envelope information that can be stored in the remaining space. If N frames are sent out in one frame, the timing duration is N * 256 ns, that is, one frame is output every N * 256 ns. Step 3: The processing backend receives the spectrum and envelope data in real time and stores them for analysis. The processing backend allocates sufficient storage space to cache the spectrum and envelope received during one radar scan; in this embodiment, a circular buffer is used, and the data is interrupted and received and stored to the tail pointer. At the same time, two circular buffers are designed to store the spectrum and envelope data respectively. Step 4: The processing backend fetches the next frame of spectrum to be analyzed and fetches a frame of spectrum data from the head pointer of the spectrum buffer. Step 5: The processing backend pre-analyzes whether there is interference based on the spectrum; whether there is a signal within the frequency bandwidth of the cooperative radar. If there is, it is predicted that there is an interference signal and recorded in the temporary interference result table; secondly, if there is a signal within 5 times the frequency bandwidth of the cooperative radar but not within the frequency bandwidth of the cooperative radar, it is predicted that there is an interference signal, and the frequency sweep mode flag is set, and at the same time it is recorded in the temporary interference result table; if neither of the above two cases is satisfied, it is predicted that there is no interference signal. The definition of the frequency bandwidth range of the cooperative radar: Let the center frequency of the preamble information be RFcenter and the bandwidth be BW, then the frequency bandwidth range of the cooperative radar is [RFcenter - BW / 2, RFcenter + BW / 2]. The presence of a signal is defined in this embodiment as: there is a frequency point within the above frequency range whose amplitude is 5 dB above the noise floor, then there is a signal at this frequency point. The temporary interference result table records all detected interference signals, including the instantaneous azimuth, instantaneous amplitude, instantaneous center frequency, and instantaneous bandwidth at the moment when the signal appears. It is created when the first prediction of an interference signal is made during the radar scan and is cleared when no interference signal is received continuously for 5° and after the characteristics of the interference signal have been analyzed. The noise floor in this embodiment is -92 dB, the center frequency of the cooperative radar is 1.35 G, and the bandwidth is 4 MHz. As shown in the appendix Figure 2 shown, the following analyzes in combination with the data segment of this frame of spectrum. The cooperative radar frequency range is from 1348 MHz to 1352 MHz. The maximum amplitude within this range is -59 dB. With a decrease of 5 dB, that is, with -64 dB as the upper limit, find the maximum amplitude respectively forward and backward. The maximum amplitude found is -58 dB. Taking this as the benchmark, with a decrease of 5 dB, that is, with -63 dB as the upper limit, find the minimum and maximum frequencies respectively forward and backward. In this example, they are 1342.8 MHz and 1351.1 MHz. Taking the maximum amplitude as the interference amplitude and the difference between the maximum and minimum frequencies as the bandwidth, it is predicted in this frame analysis that there is an interference signal near 1.35G. The result of the temporary interference signal is the instantaneous center frequency of 1346 MHz, the instantaneous bandwidth of 10 MHz, and the instantaneous amplitude of -58 dB; Step 6: If it is predicted that there is an interference signal, go to Step 4; Step 7: If it is predicted that there is no interference, analyze the temporary interference result table. If it is empty, go to Step 4; if it is not empty, compare the current azimuth information with the azimuth information of the last record in the temporary interference result table. If it is within 5°, go to Step 4; otherwise, go to the next step; Step 8: Analyze the temporary interference result table, and combine it with the corresponding original spectrum and envelope to determine the interference mode of the interference signal, including the broadband or narrowband, frequency sweeping or non-frequency sweeping, continuous or discontinuous characteristics of the interference signal, and report the interference recognition result; The analysis of the temporary interference result table, combined with the corresponding original spectrum and envelope, means that according to the start and end index numbers recorded in the temporary interference result table, collect the associated spectrum and envelope frames, and then conduct analysis; first find the maximum instantaneous amplitude, take the instantaneous azimuth and instantaneous amplitude at this moment as the azimuth and amplitude of the interference source, count the maximum and minimum values of all instantaneous center frequencies, calculate their difference as the frequency bandwidth of the interference source, and the central value as the center frequency of the interference source, and then determine the interference mode; The determination criteria for the interference mode of the interference signal are as follows: 1. Determination of broadband or narrowband: If the bandwidth of the interference signal is more than 5 times the bandwidth of the cooperative radar, it is determined as broadband suppression interference; otherwise, if it is more than 2 times the bandwidth of the cooperative radar, it is determined as narrowband suppression interference; otherwise, it is determined as spoofing interference; 2. Determination of frequency sweeping or non-frequency sweeping: If the instantaneous center frequency of the interference signal is not fixed and changes linearly or at equal intervals and other regular patterns, it is determined as frequency sweeping; otherwise, it is determined as non-frequency sweeping interference; 3. Determination of continuous or discontinuous: If the envelope of the interference signal has breakpoints and the breakpoint duration exceeds 1 ms, it is determined as discontinuous; otherwise, it is continuous; As attached Figure 3As shown, the temporarily interfered result table statistically obtains that the instantaneous maximum and minimum center frequencies are 1358 MHz and 1343 MHz respectively. Then, the bandwidth of the interference source is 15 MHz, and the center frequency is 1350 MHz, which is determined to be narrowband suppression interference. It can be seen from the envelope that the instantaneous center frequency changes sinusoidally, which is determined to be swept-frequency interference. There are breakpoints in the middle of the envelope, but the longest duration of the breakpoints is about 300 us, which is determined to be continuous interference. Step 9: Clear the temporarily interfered result table, and go back to Step 4 to continue identifying the interference signal.

[0014] The present invention is not limited to the above embodiments. Based on the technical solutions disclosed in the present invention, those skilled in the art, inspired by the above embodiments, through the above description content and according to the disclosed technical content, can make some substitutions and deformations to some technical features without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A novel suppression interference pattern analysis and identification method, characterized in that: The method comprises the following steps: Step 1: During the scanning process, the radar sends a leading signal to the matching detection and receiving equipment before each pulse is transmitted. The leading signal contains information such as the transmission time, center frequency, bandwidth, signal form, azimuth, pulse width and frame synchronization code of the next pulse; Step 2: The detection device collects the spectrum and envelope data from the current to the next leading signal in real time according to the received leading signal; Step 3: The processing front end performs digital channelization processing and accumulation on the spectrum data, and at the same time performs sliding window recording on the envelope data with a sliding window interval of 256ns, and transmits the data to the processing back end in a regular frame; Step 4: The processing backend jointly analyzes and stores the collected spectrum and envelope information to determine whether there is an interference signal; if there is an interference signal, it is recorded in the temporary interference result table and recorded as the starting index; when an interference signal is detected for the first time, the recording of the temporary interference result table is started; Step 5: When the radar rotates continuously for 5° without detecting interference, the last interference record is used as the cutoff index, and then all spectrum and envelope data between the start index and the cutoff index are extracted. The true direction of the interference source is determined by the maximum amplitude point of the interference signal, and its broadband or narrowband, swept or non-swept frequency, and continuous or intermittent characteristics are analyzed; Step 6: Output the recognition result according to the interference characteristic judgment criteria, and clear the temporary interference result table to perform subsequent detection in a loop.

2. The method for analyzing and identifying suppression interference patterns according to claim 1, characterized in that: The determination of whether there is an interference signal in step 4 specifically includes first determining whether there is a signal within the frequency bandwidth of the cooperative radar. If so, it is predicted that there is an interference signal and recorded in the temporary interference result table; secondly, if there is a signal within 5 times the frequency bandwidth of the cooperative radar, but not within the frequency bandwidth of the cooperative radar, it is predicted that there is an interference signal, and the scanning mode flag is set, and recorded in the temporary interference result table; if neither of the above two situations is met, it is predicted that there is no interference signal.

3. The method for analyzing and identifying suppression interference patterns according to claim 1, characterized in that: The analysis of the interference source orientation and characteristics in step five includes first traversing the temporary interference result table, extracting the instantaneous amplitude of all interference records, and taking the orientation corresponding to the maximum value as the true orientation of the interference source; then counting the maximum and minimum values ​​of all instantaneous center frequencies, and calculating the difference as the interference signal bandwidth; if the bandwidth is greater than 5 times the bandwidth of the cooperative radar, it is determined to be broadband suppression interference; if the bandwidth is between 2 and 5 times, it is determined to be narrowband suppression interference; if the instantaneous center frequency of the interference signal is not fixed and changes linearly or at equal intervals, it is determined to be swept frequency, otherwise it is determined to be non-swept frequency interference; if the interference signal envelope has breakpoints and the breakpoint duration exceeds 1ms, it is determined to be intermittent interference, otherwise it is continuous interference.

4. The method for analyzing and identifying suppression interference patterns according to claim 1, characterized in that: The management strategy of the temporary interference result table in step 4 includes creating a temporary table when interference is first detected and recording a starting index; When the radar azimuth rotates 5° continuously and no interference signal is received, the most recently received interference is used as the cutoff index and triggers the mode analysis. During the analysis, the maximum instantaneous amplitude is first found, and the instantaneous azimuth and instantaneous amplitude at that moment are used as the azimuth and amplitude of the interference source. The maximum and minimum values ​​of all instantaneous center frequencies are counted, and the difference is calculated as the frequency bandwidth of the interference source. The center value is used as the center frequency of the interference source, and then the interference mode is determined.

5. The method for analyzing and identifying suppression interference patterns according to claim 1, characterized in that: The combined analysis of the spectrum and envelope information in step 4 includes spectrum analysis for determining the interference frequency range and amplitude distribution, and envelope analysis for detecting signal continuity and phase characteristics; By comparing the spectrum data of adjacent frames, the frequency hopping pattern of the swept frequency interference can be identified; by combining the azimuth information, a spatial distribution map of the interference source can be established.

6. The method for analyzing and identifying suppression interference patterns according to claim 1, characterized in that: In the step three, the framing is performed according to the message protocol, with a fixed frame length, the message header, tail and leading synchronization information are removed, and the number of envelope information that can be stored in the remaining space is calculated; if a preset number of envelope information is sent in one frame, the timing duration is the preset number multiplied by the time interval, and one frame is output.

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