A method for combined suppression before and after pulse compression of air traffic control radar narrow pulse jamming

Abstract

The application discloses an air traffic control radar narrow pulse interference pulse pressure pre-post combined suppression method, which comprises the following steps: S1, saturation detection and noise accumulation are performed on original data; S2, a bearing-clutter intensity map is established, and clutter cancellation is performed; S3, anti-narrow pulse processing is performed on the pulse cancellation data and original I and Q data in the time domain; S4, step interference detection is performed on the cancellation data, and suspected interference units are marked; S5, suspected interference point confidence evaluation is performed; the confidence of the point in the suspected interference unit window is calculated, the confidence calculation is based on the eigenvalue of the point, and if the calculated confidence is lower than a preset value, the point is discarded. The method effectively solves the influence of clutter on interference detection, performs fine interference detection and suppression according to the characteristics of narrow pulse interference and asynchronous interference, and calculates the confidence of suspected interference points after point condensation, so that the influence of narrow pulse interference on point formation and track association is reduced.

Description

Technical Field

[0001] This invention belongs to the field of radar signal processing, and particularly relates to a method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar. Background Technology

[0002] Pulse radar is a commonly used radar system for detecting and tracking targets. It achieves target detection by transmitting pulse signals and receiving the echo signals reflected from the targets. However, pulse radar systems are susceptible to various interferences during operation, including narrow-pulse interference. Narrow-pulse interference refers to short-duration interference signals within the radar receiver's bandwidth, with a pulse width comparable to or narrower than the radar system's pulse width. This interference signal may originate from other radar systems, radio communication equipment, power spurs, etc. When narrow-pulse interference enters the radar receiver, it superimposes with the target echo signal, causing the target signal to be masked or severely distorted, thereby reducing the performance and reliability of the radar system. Anti-jamming design has become an important aspect of modern radar design. Narrow-pulse interference, as a common type of interference, has a good disruptive effect. Radar anti-jamming technology urgently needs further development and breakthroughs to adapt to the increasingly severe electromagnetic environment.

[0003] In the prior art, the Naval Aviation Engineering Academy of the Chinese People's Liberation Army disclosed a method for suppressing co-frequency asynchronous interference in navigation radar in its patent application: "A Method for Suppressing Intermediate Frequency Signals of Dense Co-frequency Asynchronous Interference in Navigation Radar" (Patent Application No.: 201710060299.3). This algorithm uses the envelope signal generated by the zero intermediate frequency signal to locate the co-frequency asynchronous interference in the azimuth echo of the video. Then, based on the recorded location of the co-frequency asynchronous interference, interference suppression is performed on the zero intermediate frequency I and Q real signals respectively to preserve the zero intermediate frequency phase information, laying the foundation for subsequent coherent processing of the radar signal. During the interference suppression process, a weighting coefficient and a protection factor are introduced. The protection factor is used to protect the amplitude of the original azimuth echo, so as to remove the co-frequency asynchronous interference signal while protecting the original data from modification to the greatest extent.

[0004] The 724 Research Institute of China Shipbuilding Industry Corporation disclosed a method for eliminating out-of-band interference from radar narrow pulses in its patent application, "Method for Suppressing Out-of-Band Interference from Narrow Pulses in Radar" (patent application number: 201510363924.2). This algorithm, after digital orthogonal and low-pass filtering in the signal processing flow, adds a narrow pulse out-of-band interference suppression module before the pulse compression module. It calculates the modulus of the in-phase component I and the orthogonal component Q of the radar echo signal for each range cell to obtain the echo envelope signal, which is then processed. In the azimuth slow-time direction, envelope anti-asynchronous processing is performed. Asynchronous I and Q values ​​are eliminated and compensated by comparing the echo envelope amplitudes of the same range cell during adjacent radar repetition cycles. In the range fast-time direction, three adjacent range cells are selected within the same radar repetition cycle. Based on the fluctuations of the echo at nearby ranges, the I and Q values ​​of the remaining narrow pulse signal in the corresponding range cells are eliminated and compensated.

[0005] Existing narrow pulse jamming can be divided into co-frequency asynchronous jamming and co-frequency synchronous jamming. Co-frequency asynchronous jamming is mostly caused by radars in the formation being close to each other and operating on the same frequency band. Traditional narrow pulse jamming suppression methods only suppress it by taking advantage of the fact that it does not generate interference in the same range cell in several consecutive repetition cycles before pulse compression, and assume that it is only affected by asynchronous interference in a few range cells in the time domain. Moreover, the detection requirements are quite stringent. This detection method not only ignores the influence of clutter in the geographical environment on the radar, but also cannot correlate the detected target track with the video data before detection. Therefore, the narrow pulse jamming that is not suppressed can easily interfere with the track and flight path of normal targets after it forms a track. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of the prior art by disclosing a method for joint suppression of narrow pulse interference pulse compression before and after air traffic control radar. This method effectively solves the problem of the influence of clutter on interference detection in complex environments. At the same time, it can perform fine detection and suppression of interference based on the characteristics of narrow pulse interference and asynchronous interference. After the point track is aggregated, the confidence of suspected interference point tracks is calculated, which effectively reduces the impact of narrow pulse interference on point track formation and track correlation.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar, the method comprising the following steps:

[0009] S1: Perform saturation detection and noise accumulation on the raw data;

[0010] After receiving the raw I and Q data from the radar, saturation interference is detected, and noise levels are accumulated at the range end.

[0011] S2: Establish an azimuth-clutter intensity map and perform clutter cancellation;

[0012] The original I and Q data are fed into two zero-frequency filters to estimate the clutter intensity of each range cell at the current azimuth, and the clutter-to-noise ratio at the current azimuth is calculated by the noise level. Then, an azimuth-clutter intensity map is established based on the clutter-to-noise ratio, and clutter cancellation is performed on the original I and Q data based on the azimuth-clutter intensity map.

[0013] S3: Perform time-domain inverse narrow pulse processing on the pulse cancellation data and the original I and Q data;

[0014] First, narrow pulse interference detection and suppression are performed on the pulse cancellation data in the time domain. At the same time, the same distance cells in the original I and Q data are also suppressed.

[0015] S4: Perform step interference detection on the canceled data and mark suspected interference units;

[0016] The data after cancellation is stepped by the detection threshold. The detected narrow pulse is marked as a suspected interference unit. Then, the suspected interference unit is judged for asynchronous interference. If it is asynchronous interference, it is processed for anti-asynchronous interference and the mark is cleared. At the same time, the same distance units in the original I and Q data are also processed for anti-asynchronous interference. Otherwise, the mark is stored and step S4 is continued. If no detection unit amplitude is greater than the detection threshold, step S5 is executed.

[0017] S5: Confidence assessment of suspected interference points;

[0018] The confidence level of the points within the suspected interference unit window is calculated based on the feature values ​​of the points, including amplitude, signal-to-noise ratio, number of distance cohesive points, and number of azimuth cohesive points. If the calculated confidence level is lower than a preset value, the point is discarded.

[0019] According to a preferred embodiment, step S1 includes:

[0020] S11: Perform saturation threshold detection on the raw radar echo data. If the current detection range cell is greater than the saturation threshold, then take the noise accumulation level to replace the I and Q values ​​of this cell.

[0021] According to a preferred embodiment, step S11 specifically includes:

[0022] Set saturation detection threshold If the amplitude of the detection unit exceeds the saturation threshold, it is considered that the unit has received high-intensity interference, and the current accumulated noise value is used. The corresponding detection formula, replacing the amplitude of this unit, is as follows:

[0023]

[0024] In the formula Indicates the current detection unit number. Indicates the first i The amplitude of each distance unit.

[0025] According to a preferred embodiment, step S1 further includes:

[0026] S12: At the end of the detection range, the size is The distance window is statistically averaged and accumulated. The noise accumulation formula is as follows:

[0027]

[0028] In the formula, Indicates the noise accumulation weight. Indicates the last noise update level. Indicates the current noise accumulation level;

[0029] in, This represents the average noise statistical value at the end of the current sampling distance, specifically:

[0030] .

[0031] According to a preferred embodiment, step S2 includes:

[0032] S21: The data after saturation detection is sent to the zero-frequency filter bank for clutter intensity estimation. The clutter intensity estimation formula is as follows:

[0033]

[0034] In the formula, Indicates the first clutter intensity estimates for each region, This represents the number of distance units contained in a single channel within a region, where N represents the number of sampling points within a single pulse repetition period. Indicates the current clutter region's first Units, express The first in the channel The amplitude of each unit, express The first in the channel The amplitude of each unit;

[0035] S22: An azimuth-clutter intensity map is established by accumulating noise and estimating clutter intensity. The formula is as follows:

[0036]

[0037] In the formula, This represents the stored values ​​of the azimuth-clutter intensity map, where values ​​0, 1, and 2 represent a clean area, a moderate clutter area, and a strong clutter area, respectively. This indicates the first clutter intensity decision threshold. This indicates the second clutter intensity decision threshold;

[0038] S23: Perform sliding window pulse cancellation on the original echo data based on the established azimuth-clutter intensity map. If the area in the azimuth-clutter intensity map is a clean area, no pulse cancellation is performed; if the area in the azimuth-clutter intensity map is a medium clutter area, two-pulse cancellation is performed; if the area in the azimuth-clutter intensity map is a strong clutter area, three-pulse cancellation is performed.

[0039] According to a preferred embodiment, the specific steps for performing time-domain inverse narrow pulses on the original data and the canceled data in step S3 are as follows:

[0040] Narrow pulses are detected according to a set detection threshold. If the calculated pulse width meets the specified conditions, it is considered narrow pulse interference. The clutter-cancelled data and the original echo data are then subjected to time-domain anti-narrowing processing. The time-domain anti-narrowing processing formula is as follows:

[0041]

[0042]

[0043]

[0044]

[0045] In the formula, Indicates the detection pulse width. Indicates the pulse width threshold. This represents the original echo signal. This represents the data after pulse cancellation. This indicates the noise accumulation level.

[0046] According to a preferred embodiment, step S4, which involves progressively detecting interference and marking suspected interference units, includes the following specific steps:

[0047] S41: Step up the detection threshold and continue to detect the time domain. If the detected pulse width meets the specified conditions, mark it as suspected interference. The marking method is to record the pulse width center distance cell of the suspected interference pulse and the current azimuth angle of the radar.

[0048] S42: Perform asynchronous interference detection on suspected interference units. If it is asynchronous interference, perform asynchronous interference suppression and clear the suspected interference marker. The asynchronous interference detection and suppression formulas are as follows:

[0049]

[0050]

[0051] In the formula, satisfy , satisfy , satisfy , Indicates the first [echo] in the raw echo data The first pulse One distance unit, Indicates the first data in the data after cancellation The first pulse One distance unit.

[0052] According to a preferred embodiment, the confidence level of the suspected traces in step S5 is calculated using the following formula:

[0053]

[0054] In the formula, This represents the weight of the confidence level of each feature value, and , This represents the confidence level of the dot's amplitude. The signal-to-noise ratio confidence level of the dot pattern. The confidence level represents the distance cohesion width of the dot pattern. The confidence level of the directional cohesion width of the dot pattern.

[0055] According to a preferred embodiment, in step S5:

[0056] Based on the set amplitude threshold The formula for calculating the amplitude confidence level is as follows:

[0057]

[0058] In the formula, This indicates the confidence level of the amplitude of the suspected interference point trace. Indicates the amplitude of suspected interference points;

[0059] Based on the set signal-to-noise ratio threshold The confidence score for the signal-to-noise ratio is calculated as follows:

[0060]

[0061] In the formula, This indicates the confidence level of the signal-to-noise ratio of the suspected interference point. The signal-to-noise ratio representing suspected interference points;

[0062] Based on the set distance threshold for the number of condensation points and The confidence score for the distance to convergence point count is calculated as follows:

[0063]

[0064] In the formula, This represents the confidence level of the distance from suspected interference points to the number of aggregation points. Indicates the distance from suspected interference points to the convergence point;

[0065] Based on the set azimuth condensation point threshold and The confidence score for the distance to convergence point count is calculated as follows:

[0066]

[0067] In the formula, This indicates the confidence level of the number of convergence points in the direction of suspected interference points. This indicates the number of azimuth convergence points of suspected interference points.

[0068] The aforementioned main solution of the present invention and its various further alternative solutions can be freely combined to form multiple solutions, all of which are solutions that can be adopted and are claimed by the present invention. Those skilled in the art, after understanding the solution of the present invention, will realize that there are many combinations based on existing technology and common knowledge, all of which are technical solutions to be protected by the present invention, and will not be exhaustively listed here.

[0069] The beneficial effects of this invention are:

[0070] This invention proposes a joint suppression method for narrow pulse interference before and after pulse compression, based on the operating characteristics of air traffic control radar. It can establish an azimuth-clutter intensity map based on the clutter conditions of the radar environment, and perform clutter cancellation of different degrees in different areas according to the azimuth-clutter intensity map, reducing the impact of clutter on interference detection and suppression. The step-detection method makes interference detection more refined and accurate. It can calculate the confidence level of point track data based on suspected interfered units before pulse compression, reducing the impact of unremovable interference on normal target tracks and greatly reducing the impact of narrow pulse interference on the normal operation of the radar system. Attached Figure Description

[0071] Figure 1 This is a flowchart of the pulse compression preprocessing of the air traffic control radar narrow pulse interference pulse compression joint suppression method of the present invention;

[0072] Figure 2 This is a flowchart of the pulse compression post-processing method for the combined suppression of narrow pulse interference pulses in air traffic control radar according to the present invention. Detailed Implementation

[0073] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0074] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0075] refer to Figure 1 and Figure 2 As shown in the figure, a method for joint suppression of narrow pulse interference pulse compression before and after an air traffic control radar is illustrated. This invention takes into account the operating characteristics of a two-coordinate air traffic control radar and includes the following steps:

[0076] First, saturation interference detection is performed on the data before pulse compression, and the amplitude of cells exceeding the detection threshold is suppressed.

[0077] Then, the distance cell at the end of the first echo is sampled and the noise level is statistically analyzed. A single-pole filter is used to accumulate noise between frames to reduce the impact of noise fluctuations and noise interference on the detection.

[0078] A CPI echo data is sent to a zero-frequency filter bank to estimate clutter intensity and build a clutter intensity map of the current azimuth. Based on the different heights of clutter in this map, different pulse numbers are used for cancellation to reduce the impact of clutter on interference detection.

[0079] In the time domain, narrow pulse interference is eliminated from the pulse cancellation data. Narrow pulse interference within a specified pulse width range is eliminated, and then the detection threshold is gradually increased. If the detection conditions are not met, the data is marked and further asynchronous interference is judged.

[0080] The results of point aggregation are compared with the sequence of suspected interfering points, and the confidence level is calculated. If the confidence level is too low, the point is discarded.

[0081] The method of this invention effectively solves the problem of clutter affecting interference detection in complex environments. It can also perform fine detection and suppression of interference based on the characteristics of narrow pulse interference and asynchronous interference. Furthermore, it calculates the confidence level of suspected interference points after point aggregation, effectively reducing the impact of narrow pulse interference on point formation and track correlation.

[0082] refer to Figure 1 and Figure 2 As shown, the specific technical solution of the method of the present invention includes:

[0083] (1) Perform saturation detection on the raw echo data and set the saturation detection threshold. If the amplitude of the detection unit exceeds the saturation threshold, it is considered that the unit has received a high-intensity interference, and the current accumulated noise value is used. The corresponding detection formula, replacing the amplitude of this unit, is as follows:

[0084]

[0085] In the formula Indicates the current detection unit number. This indicates the amplitude of the current detection unit.

[0086] (2) Statistical analysis of the noise level of a distance window at the end of the detection range is performed, and this level is accumulated in each scan cycle:

[0087] (2a) Set a distance window within which there are Each distance unit, for the end The statistical average of each sampling unit is calculated using the following formula:

[0088]

[0089] In the formula, This represents the average noise statistical value at the end of the current sampling distance. Indicates the first i The amplitude of each distance unit.

[0090] (2b) The noise level is accumulated, and the calculation formula is as follows:

[0091]

[0092] In the formula, Indicates the noise accumulation weight. This indicates the noise update level from the last time.

[0093] (3) Use and The filter bank estimates the clutter intensity of the raw echo data. As a unit, one of them Include One transmit pulse.

[0094] (3a) Based on the data from the zero channel, the clutter intensity is estimated. The clutter intensity estimation formula is as follows:

[0095]

[0096] In the formula, Indicates the first clutter intensity estimates for each region, This indicates the number of distance units contained in a single channel within a region. Indicates the current clutter region's first Units, express The first in the channel The amplitude of each unit, express The first in the channel The amplitude of each unit.

[0097] (3b) Based on the calculated noise accumulation level and clutter intensity estimation, an azimuth-clutter intensity map is established. (Settings...) The first clutter intensity decision threshold, The second clutter intensity decision threshold is used, and the clutter region is divided into a clean region, a moderate clutter region, and a strong clutter region according to the clutter intensity and the clutter decision threshold. The formula for establishing the azimuth-clutter intensity map is as follows:

[0098]

[0099] In the formula, This represents the values ​​stored in the azimuth-clutter intensity map, where values ​​0, 1, and 2 represent the clean area, the medium clutter area, and the strong clutter area, respectively.

[0100] (3c) Perform sliding window pulse cancellation on the original echo data based on the established azimuth-clutter intensity map. If the area in the azimuth-clutter intensity map is a clean area, no pulse cancellation is performed; if the area in the azimuth-clutter intensity map is a medium clutter area, two-pulse cancellation is performed; if the area in the azimuth-clutter intensity map is a strong clutter area, three-pulse cancellation is performed.

[0101] (4) The pulse compression pre-CPI echo sequence generated at a certain azimuth during a certain radar scan cycle. ,and ,in , This represents a pulse echo sequence. To represent a complex number of sampling points, the actual part is... The imaginary part is , This indicates the number of pulses contained within one CPI. This represents the number of sampling points within a pulse. For data after pulse cancellation based on the azimuth-clutter intensity map, it is represented as follows: ,and To address the situation where interference, targets, and clutter are separated in the time domain, time-domain pulse width detection is performed on the echo data. This detects narrow pulse interference signals generated by asynchronous operation between multiple radars at the same frequency or by artificially applied narrow pulse interference, and eliminates interference with a considerable pulse width (greater than short pulse width but less than long pulse width).

[0102] (4a) Set the detection threshold as And satisfy For the current pulse Detection is performed in the time domain, if the detection unit The amplitude is greater than the detection threshold This is the starting point of the pulse width and is denoted as . until it is less than the detection threshold. This is the endpoint of the pulse width and is denoted as . The difference between the ending point and the starting point is the pulse width. The formula for calculating pulse width is as follows:

[0103]

[0104] In the formula, This indicates the sampling rate of the baseband signal.

[0105] (4b) The detected pulse width With the set detection pulse width threshold A judgment will be made if the pulse width is less than the detection pulse width threshold. This is narrow pulse interference, which will affect the original echo signal. Signal after pulse cancellation The affected range cells are discarded, and the accumulated noise is used to eliminate them. The alternative detection and decision formula is as follows:

[0106]

[0107]

[0108]

[0109]

[0110] (5) For complex situations where interference, targets, and residual clutter overlap in the time domain, perform refined interference detection and removal. Set the detection step threshold as follows: The detection pulse width threshold is and .

[0111] (5a) Step the detection threshold That is, the detection threshold is Pulse width in the time domain The detection and calculation of pulse width are consistent with (4a), and the formula for pulse width detection and calculation is taken simultaneously. To detect the starting point of the pulse width, This is the endpoint for pulse width detection. If no detection result is found, interference detection for the current pulse ends.

[0112] (5b) Detect the pulse width The detection pulse width threshold is used to make a judgment. If it is satisfied... It is then assumed to be subject to narrow pulse interference, and the corresponding distance and direction are marked and denoted as follows. The distance calculation formula is as follows:

[0113]

[0114] In the formula, This indicates the distance to the marked point.

[0115] The radar's current servo angle is The formula for calculating direction is as follows:

[0116]

[0117] In the formula, Indicates the location of the marked point.

[0118] The amplitude of the suspected interference cell is compared with that of the cell at the same distance in the adjacent repetition period for a decision. If the interference is determined to be asynchronous narrow pulse interference, the average value of the cell at the same distance in the adjacent repetition period is used instead, and the marker number is cleared. The decision formula is as follows:

[0119]

[0120]

[0121] In the formula, satisfy , satisfy , satisfy .

[0122] (5c) Based on the previous detection video echo sequence, the detection threshold is further stepped. Then perform steps (5a) and (5b).

[0123] Repeat steps (5a), (5b), and (5c) until no detection result is found, at which point the current pulse detection ends. Then, record the original echo data after interference suppression. Send to the next signal processing step.

[0124] (6) After coherent processing and point clustering, the confidence level of suspected interference points is assessed. If the confidence level is less than a certain threshold, point filtering is performed. The point sequence after radar point clustering is as follows: .

[0125] (6a) For suspected interference unit sequences Perform a traversal; if a certain point is located at a distance of width from a suspected interference cell... The azimuth width is Within the window, there are suspected interference points, and the confidence level is evaluated based on their characteristic values. The characteristic values ​​selected in this paper are amplitude, signal-to-noise ratio, number of range-oriented cohesive points, and number of azimuth-oriented cohesive points.

[0126] (6b) Based on the set amplitude threshold The formula for calculating the amplitude confidence level is as follows:

[0127]

[0128] In the formula, This indicates the confidence level of the amplitude of the suspected interference point trace. This indicates the amplitude of the suspected interference point.

[0129] Based on the set signal-to-noise ratio threshold The confidence score for the signal-to-noise ratio is calculated as follows:

[0130]

[0131] In the formula, This indicates the confidence level of the signal-to-noise ratio of the suspected interference point. This represents the signal-to-noise ratio of suspected interference points.

[0132] Based on the set distance threshold for the number of condensation points and The confidence score for the distance to convergence point count is calculated as follows:

[0133]

[0134] In the formula, This represents the confidence level of the distance from suspected interference points to the number of aggregation points. This indicates the distance to the aggregation point of the suspected interference point.

[0135] Based on the set azimuth condensation point threshold and The confidence score for the distance to convergence point count is calculated as follows:

[0136]

[0137] In the formula, This indicates the confidence level of the number of convergence points in the direction of suspected interference points. This indicates the number of azimuth convergence points of suspected interference points.

[0138] (6c) Calculate the total confidence of the interference points based on the calculated confidence of each feature value. The calculation formula is as follows:

[0139]

[0140] In the formula, This represents the weight of the confidence level of each feature value, and Based on the set confidence threshold If satisfied If the confidence level of the dot is too low, the dot will be filtered out. If the following conditions are met... This point is then retained, and its confidence level can be used as a reference for track association.

[0141] This invention proposes a joint suppression method for narrow pulse interference before and after pulse compression, based on the operating characteristics of air traffic control radar. It can establish an azimuth-clutter intensity map based on the clutter conditions of the radar environment, and perform clutter cancellation of different degrees in different areas according to the azimuth-clutter intensity map, reducing the impact of clutter on interference detection and suppression. The step-detection method makes interference detection more refined and accurate. It can calculate the confidence level of point track data based on suspected interfered units before pulse compression, reducing the impact of unremovable interference on normal target tracks and greatly reducing the impact of narrow pulse interference on the normal operation of the radar system.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar, characterized in that, The method includes the following steps: S1: Perform saturation detection and noise accumulation on the raw data; After receiving the raw I and Q data from the radar, saturation interference is detected, and noise levels are accumulated at the range end. S2: Establish an azimuth-clutter intensity map and perform clutter cancellation; The original I and Q data are fed into two zero-frequency filters to estimate the clutter intensity of each range cell at the current azimuth, and the clutter-to-noise ratio at the current azimuth is calculated by the noise level. Then, an azimuth-clutter intensity map is established based on the clutter-to-noise ratio, and clutter cancellation is performed on the original I and Q data based on the azimuth-clutter intensity map. S3: Perform time-domain inverse narrow pulse processing on the pulse cancellation data and the original I and Q data; First, narrow pulse interference detection and suppression are performed on the pulse cancellation data in the time domain. At the same time, the same distance cells in the original I and Q data are also suppressed. S4: Perform step interference detection on the canceled data and mark suspected interference units; The data after cancellation is stepped by the detection threshold. The detected narrow pulse is marked as a suspected interference unit. Then, the suspected interference unit is judged for asynchronous interference. If it is asynchronous interference, it is processed for anti-asynchronous interference and the mark is cleared. At the same time, the same distance units in the original I and Q data are also processed for anti-asynchronous interference. Otherwise, the mark is stored and step S4 is continued. If no detection unit amplitude is greater than the detection threshold, step S5 is executed. S5: Confidence assessment of suspected interference points; The confidence level of the points within the suspected interference unit window is calculated based on the feature values ​​of the points, including amplitude, signal-to-noise ratio, number of distance cohesive points, and number of azimuth cohesive points. If the calculated confidence level is lower than a preset value, the point is discarded.

2. The method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar as described in claim 1, characterized in that, Step S1 includes: S11: Perform saturation threshold detection on the raw radar echo data. If the current detection range cell is greater than the saturation threshold, then take the noise accumulation level to replace the I and Q values ​​of this cell.

3. The method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar as described in claim 2, characterized in that, Step S11 specifically includes: Set saturation detection threshold If the amplitude of the detection unit exceeds the saturation threshold, it is considered that the unit has received high-intensity interference, and the current accumulated noise value is used. The corresponding detection formula, replacing the amplitude of this unit, is as follows: In the formula Indicates the current detection unit number. Indicates the first i The amplitude of each distance unit.

4. The method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar as described in claim 3, characterized in that, Step S1 also includes: S12: At the end of the detection range, the size is The distance window is statistically averaged and accumulated. The noise accumulation formula is as follows: In the formula, Indicates the noise accumulation weight. Indicates the last noise update level. Indicates the current noise accumulation level; in, This represents the average noise statistical value at the end of the current sampling distance, specifically: 。 5. The method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar as described in claim 4, characterized in that, Step S2 includes: S21: The data after saturation detection is sent to the zero-frequency filter bank for clutter intensity estimation. The clutter intensity estimation formula is as follows: In the formula, Indicates the first clutter intensity estimates for each region, This represents the number of distance units contained in a single channel within a region, where N represents the number of sampling points within a single pulse repetition period. Indicates the current clutter region's first Units, express The first in the channel The amplitude of each unit, express The first in the channel The amplitude of each unit; S22: An azimuth-clutter intensity map is established by accumulating noise and estimating clutter intensity. The formula is as follows: In the formula, This represents the stored values ​​of the azimuth-clutter intensity map, where values ​​0, 1, and 2 represent a clean area, a moderate clutter area, and a strong clutter area, respectively. This indicates the first clutter intensity decision threshold. This indicates the second clutter intensity decision threshold; S23: Perform sliding window pulse cancellation on the original echo data based on the established azimuth-clutter intensity map. If the area in the azimuth-clutter intensity map is a clean area, no pulse cancellation is performed; if the area in the azimuth-clutter intensity map is a medium clutter area, two-pulse cancellation is performed; if the area in the azimuth-clutter intensity map is a strong clutter area, three-pulse cancellation is performed.

6. The method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar as described in claim 5, characterized in that, In step S3, the specific steps for performing time-domain inverse narrow pulses on the original data and the canceled data are as follows: Narrow pulses are detected according to a set detection threshold. If the calculated pulse width meets the specified conditions, it is considered narrow pulse interference. The clutter-cancelled data and the original echo data are then subjected to time-domain anti-narrowing processing. The time-domain anti-narrowing processing formula is as follows: In the formula, Indicates the detection pulse width. Indicates the pulse width threshold. This represents the original echo signal. This represents the data after pulse cancellation. This indicates the noise accumulation level.

7. The method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar as described in claim 6, characterized in that, Step S4, which involves progressively detecting interference and marking suspected interference units, includes the following specific steps: S41: Step up the detection threshold and continue to detect the time domain. If the detected pulse width meets the specified conditions, mark it as suspected interference. The marking method is to record the pulse width center distance cell of the suspected interference pulse and the current azimuth angle of the radar. S42: Perform asynchronous interference detection on suspected interference units. If it is asynchronous interference, perform asynchronous interference suppression and clear the suspected interference marker. The asynchronous interference detection and suppression formulas are as follows: In the formula, satisfy , satisfy , satisfy , Indicates the first [echo] in the raw echo data The first pulse One distance unit, Indicates the first data in the data after cancellation The first pulse One distance unit.

8. The method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar as described in claim 6, characterized in that, The confidence level of the suspected traces in step S5 is calculated using the following formula: In the formula, This represents the weight of the confidence level of each feature value, and , This represents the confidence level of the dot's amplitude. The signal-to-noise ratio confidence level of the dot pattern. The confidence level represents the distance cohesion width of the dot pattern. The confidence level of the directional cohesion width of the dot pattern.

9. The method for combined suppression of narrow pulse interference pulse compression before and after air traffic control radar as described in claim 8, characterized in that, In step S5: Based on the set amplitude threshold The formula for calculating the amplitude confidence level is as follows: In the formula, This indicates the confidence level of the amplitude of the suspected interference point trace. Indicates the amplitude of suspected interference points; Based on the set signal-to-noise ratio threshold The confidence score for the signal-to-noise ratio is calculated as follows: In the formula, This indicates the confidence level of the signal-to-noise ratio of the suspected interference point. The signal-to-noise ratio representing suspected interference points; Based on the set distance threshold for the number of condensation points and The confidence score for the distance to convergence point count is calculated as follows: In the formula, This represents the confidence level of the distance from suspected interference points to the number of aggregation points. Indicates the distance from suspected interference points to the convergence point; Based on the set azimuth condensation point threshold and The confidence score for the distance to convergence point count is calculated as follows: In the formula, This indicates the confidence level of the number of convergence points in the direction of suspected interference points. This indicates the number of azimuth convergence points of suspected interference points.

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