A method and system for target radar cross section estimation

Abstract

The application discloses a target radar cross section estimation method and system, and relates to the technical field of radio and radar detection; the method comprises the following steps: forming a main scanning beam, a left accompanying beam and a right accompanying beam in a residence period, collecting echo samples to obtain an echo sample set, recording a beam serial number and a pointing angle to obtain a multi-beam pointing table, and obtaining a multi-beam power group from the echo intensity of three beams; obtaining a direction map deviation segment from the multi-beam power group and the multi-beam pointing table; aligning the direction map deviation segment with the echo sample set, and obtaining a channel consistency correction table according to a background echo segment; obtaining a de-drift echo power sequence and a maneuvering decoupling weight according to the channel consistency correction table and a tracking error sequence; the application can effectively solve the problems of the mixing of sidelobe energy caused by the beam pointing error in the prior art and the asymmetric drift of the radar cross section estimation caused by the change of the beam shape with the pointing.

Description

Technical Field

[0001] This application relates to a target radar cross-section estimation method and system, belonging to the field of radio and radar detection technology. Background Technology

[0002] In radar target detection and radar cross-section estimation scenarios, active phased array radars and digital beamforming radars typically need to calculate the target's radar cross-section based on target echo intensity, range information, and transmit power information during beam scanning or target tracking to obtain the target's scattering characteristics. Existing technologies mostly use the nominal antenna pattern and the echo of the main scanning beam as compensation bases, directly obtaining the estimated target radar cross-section after correcting the echo power according to the target's off-axis angle. This type of processing usually assumes that the deviation between the actual and nominal patterns is small, and that echo changes between adjacent dwell times mainly reflect changes in the target's own scattering characteristics.

[0003] However, in practical applications, the beam number and pointing angle continuously change during the scanning process. Besides being affected by the off-axis angle, the target echo may also be affected by sidelobe energy mixing, beam shape changes, and channel amplitude-phase consistency errors. Especially when the target is within the tracking error range or undergoes maneuvering, the echo intensity changes between adjacent dwell times not only include target scattering fluctuations but also additional fluctuations caused by beam pointing errors and tracking errors. Existing technologies typically lack the ability to separate and constrain these multiple influencing factors. A consistent processing chain is not formed between echo power compensation, channel drift constraint, and cross-dwelling time result integration, leading to an unclear correspondence between echo power changes and the actual target scattering changes.

[0004] Therefore, radar cross-section (RCS) estimates of the same target obtained under different scanning angles, beam numbers, and maneuvering states are prone to asymmetric drift and spurious correlations due to changes in the direction of movement. This results in insufficient consistency and comparability of estimation results across consecutive dwell times, making it difficult to stably reflect the true scattering characteristics of the target and further affecting target classification and threat assessment based on target RCS sequences. How to reduce the interference of beam pointing error, channel consistency changes, and tracking error coupling on target RCS estimation under conditions of simultaneous beam scanning and target maneuvering, and improve the consistency and comparability of estimation results across consecutive dwell times, has become an urgent technical problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application aims to provide a target radar cross-section estimation method and system. By constructing a multi-beam observation relationship between the main scanning beam, the left accompanying beam, and the right accompanying beam during each dwell period, and combining pattern deviation segments, channel consistency correction tables, drift-free echo power sequences, and maneuver decoupling weights, the estimated radar cross-section values ​​for each dwell period are calculated and weighted summed. This achieves the goal of suppressing beam pointing errors, sidelobe energy mixing, channel amplitude and phase consistency errors, and the asymmetric drift and spurious correlation effects of target maneuver coupling on radar cross-section estimation, and improving the consistency of radar cross-section estimation results for the same target under different scanning angles and beam numbers.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] In a first aspect, this application provides a method for estimating the radar cross-section of a target, including:

[0008] During each dwell period, a main scanning beam, a left accompanying beam, and a right accompanying beam are formed. Echo samples from the array element channels are collected to obtain an echo sample set. The beam number and pointing angle of each beam are recorded to obtain a multi-beam pointing table. The tracking error sequence, distance value, transmit power value, and calibration constant are obtained. The multi-beam power group is obtained from the intensity of the main scanning beam, the left accompanying beam, and the right accompanying beam.

[0009] Based on the multibeam power group and the multibeam pointing table, the radiation pattern deviation segment is calculated;

[0010] After aligning the pattern deviation segment with the echo sampling set, a background echo segment is selected; the channel drift value is estimated based on the background echo segment, and the channel drift value is mapped to the pattern deviation segment to obtain the channel consistency correction table;

[0011] Based on the multi-beam pointing table, pattern deviation segment and channel consistency correction table, echo power compensation is performed on the main scanning beam to obtain the drift-free echo power sequence; the maneuver decoupling weight is obtained based on the change of the tracking error sequence in adjacent dwell time periods.

[0012] Based on the drift-de-echo power sequence, range value, transmit power value, and calibration constant, the radar cross-section estimate corresponding to each dwell time period is determined. The radar cross-section estimate of each dwell time period is weighted and summed according to the maneuver decoupling weight during the continuous dwell time periods of the same target to obtain the radar cross-section estimate sequence.

[0013] By adopting the above technical solution, a multi-beam power group, a multi-beam pointing table, a pattern deviation segment, a channel consistency correction table, a drift-free echo power sequence, and a maneuver decoupling weight are synchronously established during each dwell period. This allows the pattern asymmetry caused by beam pointing error, the amplitude drift caused by channel amplitude-phase consistency error, and the pseudo-correlation caused by target maneuvering to be processed in a unified radar cross-section estimation link. This reduces the inconsistency of radar cross-section estimation results for the same target at different scanning angles, different beam numbers, and different maneuvering states, and improves the ability of the radar cross-section estimation sequence to characterize the true scattering characteristics of the target.

[0014] Preferably, the method for obtaining the distance value and the multi-beam power group includes:

[0015] The time difference between the start time of the dwell period and the arrival time of the echo is extracted from the echo sampling set, and the distance value is calculated based on the time difference.

[0016] Within a preset time interval before and after the echo arrival time, the echo intensity of the main scanning beam, the left accompanying beam, and the right accompanying beam are extracted to obtain the multi-beam power group.

[0017] By adopting the above technical solution, a unified range reference and sampling interval aperture can be established for three beams within the same dwell time period, reducing the power deviation between different beams due to inconsistent sampling times, and improving the data consistency when multi-beam power groups participate in the calculation of subsequent pattern deviation segments.

[0018] Preferably, the method for obtaining the pattern deviation segment includes:

[0019] Extract the beam number and pointing angle from the multi-beam pointing table, and calculate the power difference sequence from the echo intensity of the left accompanying beam and the echo intensity of the right accompanying beam in the multi-beam power group.

[0020] The scanning angle is recorded using the pointing angle of the main scanning beam. The scanning angle records are grouped according to a preset angle step size to obtain the scanning angle group identifier.

[0021] The power difference sequence is aggregated according to the scanning angle grouping identifier and beam number to obtain the pattern deviation segment.

[0022] By adopting the above technical solution, the degree of energy asymmetry between the left and right accompanying beams and the main scanning beam under different dwell times can be grouped and expressed according to the scanning angle grouping identifier and beam number, providing a basis for subsequent main scanning beam echo power compensation based on the pattern deviation corresponding to the scanning angle change.

[0023] Preferably, the method for obtaining the channel consistency correction table includes:

[0024] Based on the multi-beam pointing table, the beam number and pointing angle of the main scanning beam are extracted according to the dwell time period, and the pointing angle is assigned to the scanning angle grouping identifier of the pattern deviation segment to obtain the alignment result;

[0025] Based on the alignment results, a preset time interval before and after the arrival time of the echo is determined within the echo sampling set, and a candidate background interval is selected outside the preset time interval before and after the arrival time of the echo to obtain the background echo segment.

[0026] The channel drift aggregation value is obtained based on the background echo segment, and the channel drift aggregation value is aligned with the pattern deviation segment according to the scanning angle grouping identifier and beam number to obtain the channel consistency correction table.

[0027] By adopting the above technical solution, background echo segments can be extracted from the echo sampling set and channel drift aggregation values ​​can be established without adding new acquisition links. This allows the pattern deviation segments to have a basis for channel consistency correction when participating in the main scanning beam echo power compensation, thereby reducing the impact of channel amplitude and phase consistency errors on radar cross-section estimation results.

[0028] Preferably, the method for obtaining channel drift aggregation values ​​based on background echo segments includes:

[0029] The background echo intensity sequence is extracted by the array element channel, and the value in the middle position after arranging the background echo intensity sequence according to the numerical value is taken as the representative value of the background echo intensity.

[0030] After summarizing the representative values ​​of the background echo intensity of each array element channel, sort them in descending order, and use the representative value of the background echo intensity in the middle position as the channel reference value.

[0031] The difference between the representative value of the background echo intensity of each array element channel and the channel reference value is used as the channel drift value;

[0032] The channel drift values ​​corresponding to the same scan angle group identifier and the same beam number are aggregated to obtain the aggregated channel drift value.

[0033] By adopting the above technical solution, the relative difference between array element channels can be used as the basis for determining the channel drift value, reducing the interference of a single background sampling point or local abnormal echo on the channel consistency correction result, and improving the usability of the channel drift aggregation value.

[0034] Preferably, the method for obtaining the drift-free echo power sequence includes:

[0035] Extract the echo power of the main scanning beam from the multi-beam power group, locate the power difference aggregation result in the pattern deviation segment according to the scanning angle grouping identifier and beam number, and locate the channel drift aggregation value in the channel consistency correction table;

[0036] Using the echo power of the main scanning beam as a normalization benchmark, the power difference aggregation result and the channel drift aggregation value are processed to be dimensionless to determine the compensation direction and compensation amplitude. The echo power of the main scanning beam is then compensated according to the compensation direction and compensation amplitude to obtain the drift-free echo power sequence.

[0037] By adopting the above technical solution, the influence of left-right energy asymmetry reflected by the pattern deviation segment and the influence of channel drift reflected by the channel consistency correction table can be jointly mapped onto the echo power of the main scanning beam for compensation, thereby reducing the asymmetric drift component in the echo power.

[0038] Preferably, the method for obtaining the maneuver decoupling weights includes:

[0039] The tracking error sequence is sorted by dwell time period, and the difference between adjacent dwell time periods is extracted to obtain the direction and magnitude of error change;

[0040] The range of values ​​for the maneuver decoupling weight is determined based on the magnitude of error change and the preset threshold for the magnitude of error change, and the maneuver decoupling weight is adjusted based on the consistency of the direction of error change within the preset number of continuous dwell periods.

[0041] By adopting the above technical solution, the continuous changing trend of tracking error during target maneuvering can be further decoupled from the radar cross-section estimate corresponding to the drift echo power sequence, thereby reducing the probability of a spurious correlation between the radar cross-section estimate and the target maneuvering direction.

[0042] Preferably, the method for determining the radar cross-section estimate corresponding to each dwell time period includes:

[0043] The drift-de-echo power sequence, distance value, and transmit power value are sorted by dwell time period;

[0044] For each dwell period, the transmit power value is first used to normalize the drift echo power sequence value, then the round-trip propagation attenuation compensation is performed based on the distance value, and converted with the calibration constant to obtain the radar cross-section estimate value corresponding to each dwell period.

[0045] By adopting the above technical solution, the effects of changes in transmit power and propagation distance can be eliminated before the drift-de-echo power sequence values ​​are entered into the radar cross-section conversion. Then, the radar cross-section estimation under a unified dimension can be completed by combining the calibration constant, thereby improving the comparability of radar cross-section estimates between different dwell times.

[0046] Preferably, the digital beamforming weighted synthesis method is determined according to the beam number and pointing angle of the multi-beam pointing table, and the digital beamforming weighted synthesis method is the set of weighting coefficients for each array element channel;

[0047] The echo samples of each array element channel are weighted and synthesized according to the weighted coefficient set to obtain the beam echo sampling sequence. The sum of the squared amplitudes of the beam echo sampling sequence is then normalized according to the number of sampling points to obtain the echo intensity.

[0048] By adopting the above technical solution, different beams can obtain corresponding echo intensities under the weighted synthesis method of digital beamforming corresponding to the pointing angle, which provides a basis for the unified construction of multi-beam power groups.

[0049] Preferably, the calibration constant is taken from the calibration results of the calibration process;

[0050] The calibration process includes: pointing the radar at the calibration target to form the main scanning beam, the left accompanying beam and the right accompanying beam; collecting the echo sampling set to obtain the multi-beam power group, the drift-de-echo power sequence value, the range value and the transmit power value; and establishing the corresponding relationship based on the radar cross-section of the calibration target to form the calibration constant.

[0051] The calibration constants are indexed according to the beam number.

[0052] By adopting the above technical solution, the calibration constant can be kept consistent with the echo processing link under the current working mode and beam number, thereby improving the amplitude scaling consistency in the radar cross-section estimation process.

[0053] Preferably, the method for obtaining the radar cross-section estimation sequence includes:

[0054] For the continuous dwell time of the same target, a preset aggregation window length is set. During the continuous dwell time, the window is slid-selected, and the radar cross-section estimate within the sliding window is weighted and summed according to the proportion of the maneuver decoupling weight to the sum of all maneuver decoupling weights within the window.

[0055] For continuous dwell time periods, the preset aggregation window length is shortened according to the set shortening rules, and the radar cross-section estimates within the sliding window are weighted and summed according to the maneuver decoupling weights to obtain the radar cross-section estimate sequence.

[0056] By adopting the above technical solution, radar cross-section estimates corresponding to multiple dwelling periods can be smoothly aggregated within a continuous dwelling period, while taking into account the amount of available data at the boundary of the continuous dwelling period, thus reducing the impact of local fluctuations on the overall continuity of the radar cross-section estimation sequence.

[0057] Secondly, this application provides a target radar cross-section estimation system, comprising:

[0058] The beam acquisition module is used to form the main scanning beam, the left accompanying beam, and the right accompanying beam during each dwell period. It acquires echo samples from the array element channels to obtain an echo sample set, records the beam number and pointing angle of each beam to obtain a multi-beam pointing table, and obtains the tracking error sequence, distance value, transmit power value, and calibration constant. It also obtains the multi-beam power group from the intensity of the main scanning beam, the left accompanying beam, and the right accompanying beam.

[0059] The beam deviation module calculates the pattern deviation segment based on the multi-beam power group and the multi-beam pointing table.

[0060] The beam correction module is used to align the pattern deviation segment with the echo sampling set, select the background echo segment, estimate the channel drift value based on the background echo segment, map the channel drift value to the pattern deviation segment, and obtain the channel consistency correction table.

[0061] The beam weighting module, based on the multi-beam pointing table, pattern deviation segment, and channel consistency correction table, performs echo power compensation on the main scanning beam to obtain the drift-free echo power sequence; and obtains the maneuver decoupling weight based on the changes in the tracking error sequence during adjacent dwell periods.

[0062] The area estimation module determines the radar cross-section estimate for each dwell time period based on the drift-free echo power sequence, range value, transmit power value, and calibration constant. It then performs a weighted summation of the radar cross-section estimates for each dwell time period on the same target according to the maneuver decoupling weight to obtain the radar cross-section estimation sequence.

[0063] Compared with the prior art, the beneficial effects achieved by this application are as follows:

[0064] This application first generates a multi-beam power group and a multi-beam pointing table by forming a main scanning beam, a left-side accompanying beam, and a right-side accompanying beam during each dwell period. Then, a pattern deviation segment is obtained based on the multi-beam power group and the multi-beam pointing table. The pattern deviation segment is aligned with the echo sampling set to obtain a channel consistency correction table. Subsequently, a drift-free echo power sequence is obtained based on the pattern deviation segment and the channel consistency correction table. Combining the tracking error sequence, a maneuver decoupling weight is obtained. Finally, the radar cross-section estimate corresponding to each dwell period is determined based on the drift-free echo power sequence, range value, transmit power value, and calibration constant. The radar cross-section estimate sequence is obtained by weighted summation according to the maneuver decoupling weight during consecutive dwell periods of the same target. This addresses the problem of insufficient compensation caused by compensating for target echo power based solely on the nominal pattern in existing technologies. It also handles the influence of pattern asymmetry caused by beam pointing error, amplitude drift caused by channel amplitude and phase consistency error, and spurious correlation caused by target maneuvering, reducing the occurrence of asymmetric drift and maneuver coupling offset in the radar cross-section estimate results.

[0065] This application further improves the consistency and continuity of radar cross-section estimation results under different scanning angles, different beam numbers, and different dwell times by extracting background echo segments from the echo sampling set to estimate channel drift aggregation values, unifying the echo intensity of different beams to form the aperture through digital beamforming weighted synthesis, establishing the correspondence between calibration constants and radar cross-section through calibration procedures, and weighting and summing the radar cross-section estimates in continuous dwell time periods by preset aggregation window length and maneuver decoupling weights. This provides a more reliable data foundation for subsequent target category discrimination and threat assessment based on radar cross-section sequences. Attached Figure Description

[0066] Figure 1 This is a schematic diagram of a target radar cross-section estimation system according to an embodiment of this application;

[0067] Figure 2 This is a flowchart of a target radar cross-section estimation method according to an embodiment of this application;

[0068] Figure 3 This is a flowchart illustrating the method for obtaining the motor decoupling weights according to an embodiment of this application. Detailed Implementation

[0069] The technical solutions of this application will be described in detail, clearly, and completely below with reference to the accompanying drawings of the embodiments. It should be particularly noted that the specific embodiments described below are only used to better illustrate and explain the technical solutions of this application, and are intended to enable those skilled in the art to better understand and implement this application, and should not be construed as limiting the scope of protection of this application. Without departing from the spirit and substance of this application, those skilled in the art can modify, adjust, or make equivalent substitutions based on the content disclosed in this application, and these modifications, adjustments, or equivalent substitutions should all be considered within the scope of protection of this application.

[0070] Example 1

[0071] Please see Figure 1 As shown, this embodiment discloses a target radar cross-section estimation system, including a beam acquisition module, a beam deviation module, a beam correction module, a beam weighting module, and an area estimation module. Each module is connected by wired or wireless means to realize data transmission.

[0072] The beam acquisition module is used to form the main scanning beam, the left accompanying beam, and the right accompanying beam during each dwell period. It acquires echo samples from the array element channels to obtain the echo sample set, records the beam number and pointing angle of each beam to obtain the multi-beam pointing table, obtains the tracking error sequence, distance value, transmit power value, and calibration constant, and obtains the multi-beam power group from the intensity of the main scanning beam, the left accompanying beam, and the right accompanying beam.

[0073] To establish a common-source observation basis for the main scanning beam, the left accompanying beam, and the right accompanying beam during each dwell period, this implementation method focuses on data acquisition and organization around echo sampling sets, multi-beam pointing tables, tracking error sequences, distance values, transmit power values, calibration constants, and multi-beam power groups.

[0074] A main scanning beam, a left-side accompanying beam, and a right-side accompanying beam are formed, and a multi-beam pointing table is established. The pointing angle of the main scanning beam is determined for each dwell time period, taking the angle value corresponding to the current scanning angle. The pointing angles of the left-side and right-side accompanying beams are determined within the same dwell time period. The pointing angles of the left-side and right-side accompanying beams have equal angle differences on both sides of the pointing angle of the main scanning beam. The selection rule for the angle difference is that the echo intensity corresponding to the left-side and right-side accompanying beams is within the roll-off region of the main scanning beam's radiated energy, and the echo intensity corresponding to the left-side and right-side accompanying beams has a distinguishing effect on the pointing angle change. The beam number and pointing angle corresponding to each beam are recorded, and the results are sorted and summarized by dwell time period to obtain the multi-beam pointing table. An angle reference for the three beams within the same dwell time period is provided to reduce the deviation in echo intensity comparison caused by inconsistent angle references introduced by scanning angle changes.

[0075] When obtaining the echo sampling set based on the multi-beam pointing table acquisition array element channel echo sampling, a main scanning beam, a left accompanying beam, and a right accompanying beam are formed within each dwell time period. Each dwell time period consists of three consecutive receiving sub-periods, which are arranged in a fixed order within the same dwell time period: main scanning beam receiving sub-period, left accompanying beam receiving sub-period, and right accompanying beam receiving sub-period. The three receiving sub-periods share the same range gate configuration, which is determined based on the distance value. The range gate configuration includes the range gate center and the range gate width. The echo arrival time corresponding to the distance value is taken. The selection rule for the distance gate width is to cover the concentrated range of echo intensity within the echo sampling set and not exceed the available sampling duration of a single receiving sub-period within the dwell time. The three receiving sub-periods share the same echo arrival time neighborhood aperture. The echo arrival time neighborhood takes a fixed time delay window relative to the center of the distance gate in all three receiving sub-periods. This ensures that the echo sampling intervals of the main scanning beam, the left accompanying beam, and the right accompanying beam remain consistent in the sense of the distance gate within the same dwell time, reducing the power difference offset introduced by the time offset of the sampling interval.

[0076] Based on the beam number and pointing angle in the multi-beam pointing table, the system enters the main scanning beam receiving sub-segment, the left accompanying beam receiving sub-segment, and the right accompanying beam receiving sub-segment respectively during each dwell period. Within each receiving sub-segment, array element channel echo sampling is performed. Array element channel echo sampling includes amplitude and phase information. Array element channel echo sampling uses a sampling time window, with the start time of the sampling time window fixed relative to the start time of the dwell period, and the end time of the sampling time window also fixed relative to the start time of the dwell period. Array element channel echo sampling obtains a sampling sequence according to the sampling frequency within the sampling time window. The sampling sequence is a chronologically ordered sequence of samples. The sampling point set contains amplitude and phase information. The sampling frequency is selected to retain the details of echo intensity change in the neighborhood of the echo arrival time. The number of sampling points meets the upper limit constraint of the number of sampling points within the dwell time period. The upper limit of the number of sampling points is determined based on the available duration of the receiving sub-period, the sampling frequency, and the data carrying capacity constraint within the dwell time period. The sampling sequences of each array element channel in the three receiving sub-periods are summarized according to the beam number and the dwell time period identifier to obtain the echo sampling set. The echo sampling set retains the receiving sub-period identifiers of the main scanning beam, the left accompanying beam, and the right accompanying beam, which are used to distinguish the echo sampling sources of array element channels of different beams within the same dwell time period.

[0077] Tracking error records are output in units of receiving sub-segments within each dwell period. The tracking error records include tracking errors for the main scanning beam receiving sub-segments, tracking errors for the left accompanying beam receiving sub-segments, and tracking errors for the right accompanying beam receiving sub-segments. The tracking error sequence is obtained by sorting by dwell period, and the tracking error sequence retains the receiving sub-segment identifier within the dwell period. By dividing the receiving sub-segments by dwell period, constraining the neighborhood aperture of the echo arrival time by range gate configuration, and organizing the echo sampling set and tracking error sequence by receiving sub-segment identifier, the echo sampling intervals of the main scanning beam, the left accompanying beam, and the right accompanying beam are kept consistent in the sense of range gate within the same dwell period. This reduces the power difference caused by time offset error mixing under conditions of high-speed maneuvering or rapid changes in scanning angle, and reduces the risk of echo intensity distortion caused by sidelobe energy mixing and time offset superposition.

[0078] The distance values ​​are obtained based on the echo sampling set and a distance value sequence aligned with the dwell time period is formed. Based on the echo sampling set corresponding to the main scanning beam, the amplitude information corresponding to each sampling point is read in the order of sampling time within the main scanning beam receiving sub-period to determine the position where the echo intensity reaches its maximum, and the sampling time corresponding to the position is taken as the echo arrival time. The start time of the dwell time period is used as the time reference, and the time difference between the start time of the dwell time period and the echo arrival time is extracted. The time difference represents the round-trip propagation time of the radar transmitted signal from the transmitting end, through the target reflection, and back to the receiving end. Therefore, based on the predetermined propagation speed and round-trip propagation relationship, the time difference is converted into the one-way propagation distance between the target and the radar to obtain the distance value. In specific processing, the time difference is first mapped to the propagation path length, and then the propagation path length is converted into the one-way distance according to the round-trip path, which is taken as the distance value of the dwell time period. The distance values ​​obtained in each dwell time period are sorted according to the dwell time period to form a distance value sequence.

[0079] First, candidate peak positions are defined in the echo sampling set corresponding to the main scanning beam receiving sub-period. Then, the peak position that matches the main scanning beam number corresponding to the multi-beam pointing table is selected from the candidate peak positions as the position corresponding to the echo arrival time. This avoids using peak positions formed by mixing in the left and right accompanying beams or sidelobe energy as the source of range values. If multiple candidate peak positions are all located in the echo sampling set corresponding to the main scanning beam number, the peak position with the largest echo intensity is selected as the position corresponding to the echo arrival time. The time difference is converted into a range value according to the relationship between the propagation path length and the one-way distance. By defining the selection caliber that matches the main scanning beam number for multiple peak positions, a consistent range reference can be provided for the same target in different dwell times. This reduces the echo intensity sampling position offset caused by inconsistent range references and reduces the power drift caused by sampling position offset in target radar cross-section estimation.

[0080] The system acquires transmit power values ​​and calibration constants, organizing them according to dwell time periods. Transmit power values ​​are taken from the transmit power record corresponding to each dwell time period. The transmit power record is obtained by measuring the transmit power within the dwell time period using the transmit link. The transmit power values ​​are sorted by dwell time period to form a transmit power value sequence. Calibration constants are preset constants, taken from pre-established calibration results. Calibration constants characterize the amplitude scaling relationship between the echo sampling set and the transmit power value. Calibration constants are indexed according to the operating mode and beam number, and the corresponding values ​​are retrieved within the dwell time period. When the operating mode is switched, the calibration constants are updated according to the index of the switched operating mode. This provides a unified scaling constraint for echo intensity under different dwell times and different beam numbers, reducing the incomparability of echo intensity caused by transmit power value fluctuations and scaling inconsistencies.

[0081] When acquiring the tracking error sequence and obtaining the multi-beam power group from the echo intensity of the three beams, the tracking error sequence is taken from the tracking error record within a continuous dwell time period. The tracking error sequence is obtained by sorting by dwell time period, and the dwell time period identifier of the tracking error sequence is consistent with the dwell time period identifier of the main scanning beam echo power, which is used as the calculation caliber for the value of the maneuver decoupling weight. The main scanning beam receiving sub-period, the left accompanying beam receiving sub-period, and the right accompanying beam receiving sub-period are arranged adjacently within the same dwell time period. The selection rule for the time interval between the three receiving sub-periods is that the change angle of the target direction within the time interval does not exceed 0.1 times the angle difference between the left and right accompanying beams relative to the main scanning beam, thereby maintaining the same source comparison relationship of the three beams at the dwell time scale and reducing the proportion of power difference introduced by time mismatch.

[0082] Based on the echo sampling set, range value sequence, and multi-beam pointing table, the sampling interval is determined by the neighborhood of the echo arrival time corresponding to the range value during each dwell period. The selection rules for the preset duration interval before and after the echo arrival time are that the sum of the preset duration interval before and after the echo arrival time covers more than 90% of the continuous sampling segment where the main energy of the target echo is located, and the total duration does not exceed 40% of the available sampling time of a single receiving sub-period. The sampling interval shares the same range gate configuration and the same neighborhood of the echo arrival time in the main scanning beam receiving sub-period, the left accompanying beam receiving sub-period, and the right accompanying beam receiving sub-period.

[0083] The echo sampling sets of the main scanning beam, the left accompanying beam, and the right accompanying beam are processed separately. During processing, the digital beamforming weighted synthesis method corresponding to the current beam is determined based on the beam number and pointing angle of the multi-beam pointing table. The digital beamforming weighted synthesis method includes the weighting coefficient set of each array element channel, which is determined by the beam number and pointing angle index. In specific settings, the spatial position of each array element channel relative to the array reference position is first determined based on the array arrangement relationship. Then, the propagation path difference of each array element channel relative to the array reference position is determined based on the pointing angle of the current beam. Finally, the phase compensation amount is set for each array element channel based on the propagation path difference, so that the target echo from the pointing angle of the currently processed beam is converted to a unified phase parameter on each array element channel. After setting the phase compensation amount, the amplitude weight is set according to the position of each array element channel in the array. For example, the amplitude weight of the array element channel within 40% of the position of the array center is 1, the amplitude weight of the array element channel within 30% of the position of each side of the array is 0.7, and the amplitude weight of the array element channel within 20% of the position of each outermost position of the array is 0.4. The basis for setting the amplitude weight is that the position of the array center contributes more to the formation of the main lobe energy, and the position of the array edge has a greater impact on the side lobe lifting. Therefore, as the position of the array element channel changes from the array center to the array edge, the amplitude weight decreases in the order of 1, 0.7, and 0.4. The phase compensation amount of each array element channel is combined with the amplitude weight to form the weighting coefficient corresponding to the current beam.

[0084] The sampling sequence is based on the sampling times within the sampling interval. At each sampling time, the amplitude and phase information of all array element channels are read. The amplitude and phase information of each array element channel at the sampling time are then converted into complex sample values. These complex sample values ​​are multiplied by the weighting coefficients of the corresponding array element channels to obtain the weighted result of the array element channels at the sampling time. The weighted results of all array element channels at the same sampling time are then summed to obtain the composite sample value of the beam at the sampling time. The above processing method is applied to all sampling times within the sampling interval to obtain the beam echo sampling sequence. The amplitude scale of the beam echo sampling sequence is determined by the calibration constant. The amplitude scale is updated by the calibration constant index under different operating modes and different beam numbers to maintain the comparability of the echo intensity of the three beams.

[0085] Within the echo intensity sampling interval, the sum of the squared amplitudes of the beam echo sampling sequence is aggregated according to the number of sampling points. The echo intensity of the main scanning beam, the echo intensity of the left accompanying beam, and the echo intensity of the right accompanying beam are summarized according to the dwell time to obtain a multi-beam power group. The multi-beam power group and the tracking error sequence are then output in alignment according to the dwell time. By limiting the sampling time of the tracking error record to the main scanning beam reception sub-period, and limiting the sampling interval of the three beam echo intensities to a shared range gate configuration and echo arrival time neighborhood aperture, the calculation time of the maneuver decoupling weight is consistent with the sampling time of the main scanning beam echo power. The three beam echo intensities maintain the same source comparison basis at the dwell time scale, reducing the pseudo-correlation power fluctuations introduced by the superposition of scanning angle changes and tracking error changes, and reducing the asymmetric drift caused by beam number differences and maneuver direction coupling in target radar cross-section estimation.

[0086] The beam deviation module calculates the pattern deviation segment based on the multi-beam power group and the multi-beam pointing table.

[0087] The records in the pattern deviation segment do not represent the actual pattern offset angle, but rather the degree of energy asymmetry between the left and right accompanying beams relative to the main scanning beam under the same scan angle grouping identifier and the same beam number. The pattern deviation segment is used as a compensation parameter segment for subsequent echo power compensation.

[0088] Based on a multi-beam pointing table, the dwell time alignment and the consistent definition of the left and right accompanying beams are completed. The multi-beam pointing table is sorted by dwell time, and the beam number and pointing angle of the main scanning beam, left accompanying beam, and right accompanying beam are extracted for each dwell time. The left and right accompanying beams are defined by the relationship between the pointing angles of the left and right accompanying beams and the pointing angle of the main scanning beam. The beam with a pointing angle smaller than that of the main scanning beam is recorded as the left accompanying beam, and the beam with a pointing angle larger than that of the main scanning beam is recorded as the right accompanying beam. If more than one beam that meets the left or right conditions appears in a certain dwell time, the beam with the closest angle difference to the pointing angle of the main scanning beam is selected first to ensure that the relative positional relationship of the left and right accompanying beams is consistent with that of the main scanning beam. By unifying the definition of the left and right accompanying beams, the power difference sign flip caused by the mixing of the left and right accompanying beams is reduced.

[0089] The echo intensity of the left and right accompanying beams is extracted based on a multi-beam power group, forming a power difference sequence during the dwell time. The echo intensity of the left and right accompanying beams is scaled using the same amplitude and processed within the linear power domain. The echo intensity of the left and right accompanying beams during the dwell time is extracted from the multi-beam power group. The power difference between the left and right accompanying beams is calculated, and the power difference is the difference between their echo intensity. The difference between the left and right accompanying beam echo intensity is used as the first quantity, and the sum of their echo intensity is used as the second quantity. The first quantity is divided by the second quantity to obtain an asymmetric ratio. When the second quantity is less than... When the echo intensity of the main scanning beam is 20% of the lower limit, the asymmetry ratio is not calculated. When the asymmetry ratio is positive, it indicates that the echo intensity of the left accompanying beam is greater than that of the right accompanying beam. When the asymmetry ratio is negative, it indicates that the echo intensity of the right accompanying beam is greater than that of the left accompanying beam. The larger the absolute value of the asymmetry ratio, the greater the degree of energy asymmetry between the left and right sides. For each dwell time period, the dwell time identifier, main scanning beam number, main scanning beam pointing angle, power difference, and asymmetry ratio are recorded and arranged in the order of dwell time periods to form a power difference sequence. In order to reduce the interference of target scattering fluctuations on the power difference sequence in the target radar cross-section estimation, the echo intensity of the main scanning beam is extracted in the same dwell time period, and the power difference, asymmetry ratio, and main scanning beam echo intensity are associated and saved.

[0090] The power difference sequences are merged according to the scan angle and beam number to form the basic segments of the pattern deviation segment; the main scan beam pointing angle is used as the scan angle record, and the scan angle records are grouped according to a preset angle step size to obtain scan angle group identifiers; the scan angle grouping adopts a preset angle step size, and the selection rule of the angle step size is that the angle step size is less than the angle difference between the left and right accompanying beams relative to the main scan beam, and the angle step size is greater than the fluctuation amplitude of the single dwell time of the tracking error sequence to ensure that the scan angles within the same group are comparable; the power difference sequences within each scan angle group are merged according to the beam number, and those belonging to the same beam are grouped together. The scanning angle group identifier and the power difference and asymmetry ratio of the same beam number are arranged to form corresponding data sets. The value corresponding to the middle position in the data set corresponding to the power difference is taken as the power difference aggregation result under the scanning angle group identifier and beam number. The value corresponding to the middle position in the data set corresponding to the asymmetry ratio is taken as the pattern deviation parameter under the scanning angle group identifier and beam number. The pattern deviation parameter is used to characterize the degree of left and right energy asymmetry after normalization. The scanning angle group identifier, beam number, power difference aggregation result and pattern deviation parameter are recorded in correspondence to obtain the basic segment of the pattern deviation segment.

[0091] The background echo intensity reference value is pre-established before the radiation pattern deviation segment calculation. Specifically, during the dwell period when no target enters the range gate, the echo intensity of the main scanning beam is extracted according to the working mode, scanning angle grouping identifier, and beam number. The echo intensity of the main scanning beam under the same working mode, the same scanning angle grouping identifier, and the same beam number is arranged according to the numerical value, and the value corresponding to the middle position is taken as the background echo intensity reference value. The background echo intensity reference value is saved according to the working mode, scanning angle grouping identifier, and beam number, and is used to determine the preset lower limit of the main scanning beam echo intensity in the future.

[0092] The power difference validity screening of the basic segments of the pattern deviation segment is performed by combining the echo intensity of the main scanning beam; for the power difference sequence within each scanning angle group, the echo intensity of the main scanning beam is read; a preset lower limit of the echo intensity of the main scanning beam is set, which is determined based on the pre-statistically obtained background echo intensity benchmark value, and the selection rule is that the target echo and background echo segments can be distinguished within the neighborhood of the echo arrival time corresponding to the distance value; only the power difference sequence of the dwell time with the echo intensity of the main scanning beam greater than or equal to the lower limit of the echo intensity of the main scanning beam is retained to participate in the determination of the power difference aggregation result and the pattern deviation parameter.

[0093] For scanning angle groups that do not meet the lower limit of the main scanning beam echo intensity, the obtained power difference aggregation result and pattern deviation parameter are selected from the adjacent scanning angle groups as supplementary results. When supplementing, the selection range of adjacent scanning angle groups is preferably one to three scanning angle groups before and after the current scanning angle group, and the selection rule is that the selection range does not cross the beam number switching point. If there is already a power difference aggregation result that meets the lower limit of the main scanning beam echo intensity in the closer adjacent scanning angle groups, the power difference aggregation result corresponding to the scanning angle adjacent group closest to the current scanning angle group is selected first.

[0094] Output pattern deviation segments while maintaining index consistency with the multi-beam pointing table; sort the filtered scan angle grouping identifiers, beam numbers, and power difference aggregation results by scan angle to form pattern deviation segments; the pattern deviation segments retain the scan angle expression consistent with the multi-beam pointing table, with the scan angle taken as the group center value of the main scan beam pointing angle; the power difference aggregation result in the pattern deviation segment represents the absolute difference between the left and right accompanying beams in the linear power domain, and the pattern deviation parameter represents the normalized degree of left-right energy asymmetry; when the pattern deviation parameter is positive, the main scan beam echo power compensation direction is the direction of reducing the main scan beam echo power; when the pattern deviation parameter is negative, the main scan beam echo power compensation direction is the direction of increasing the main scan beam echo power; the absolute value of the pattern deviation parameter and the power difference aggregation result are used together to determine the compensation amplitude; the pattern deviation segments also retain beam numbers to distinguish the differences in energy asymmetry morphology under different beam numbers.

[0095] The beam correction module is used to align the pattern deviation segment with the echo sampling set, select the background echo segment to estimate the channel drift value, map the channel drift value to the pattern deviation segment, and obtain the channel consistency correction table.

[0096] To obtain the channel consistency correction table, this implementation method, without increasing the amount of data collected, selects background echo segments to estimate channel drift values ​​based on the co-origin residence time organization relationship between the pattern deviation segments and the echo sampling sets, and then maps the channel drift values ​​to the pattern deviation segments.

[0097] When establishing the alignment results between the pattern deviation segment and the echo sampling set, firstly, each dwell time period is processed according to the dwell time order based on the multi-beam pointing table. For the dwell time period being processed, the beam number and pointing angle of the main scanning beam are extracted. Then, the scanning angle grouping identifier and beam number are extracted from each record in the pattern deviation segment, and the scanning angle grouping identifier to which the main scanning beam pointing angle belongs is determined based on the main scanning beam pointing angle. Subsequently, records in the pattern deviation segment whose scanning angle grouping identifier is consistent with the scanning angle grouping identifier to which the main scanning beam pointing angle belongs, and whose beam number is consistent with the main scanning beam beam number, are selected as the records currently being processed. Record the pattern deviation segment corresponding to the dwell time period; record the dwell time period identifier, the corresponding scan angle group identifier, and the corresponding main scan beam number of the currently processed dwell time period as a correspondence; repeat the above processing for all dwell time periods, and arrange each correspondence according to the dwell time period order to form an alignment result; the alignment result unifies the dwell time period organization method of the echo sampling set and the scan angle grouping organization method of the pattern deviation segment under the same correspondence, reducing the mismatch of the reference object caused by the scan angle switching and beam number switching, and reducing the angular drift introduced by the pattern deviation segment driven by the echo of the wrong dwell time period.

[0098] Based on the alignment results, background echo segments are selected within the echo sampling set. For each dwell time period, the neighborhood of the echo arrival time is determined according to the distance value. The neighborhood of the echo arrival time is a preset duration interval before and after the echo arrival time corresponding to the distance value. The selection rule for the preset duration interval is to cover the concentrated interval of echo intensity within the echo sampling set. The sampling interval outside the neighborhood of the echo arrival time is used as the candidate background interval. The candidate background interval is selected from one segment before and one segment after the neighborhood of the echo arrival time. The selection rule for the duration of a single segment is that the duration of a single segment is greater than the duration of the neighborhood of the echo arrival time and less than the upper limit of the available sampling duration within the dwell time period. Subsequently, under the beam sequence number corresponding to the dwell time period being processed, the echo samples of the array element channels are extracted one by one from the candidate background interval, and arranged in the order of sampling time to form the background sampling segments of the array element channels. Then, the background sampling segments of each array element channel are recorded according to the array element channel number to form the background echo segments corresponding to the current dwell time period and the current beam number. The background echo segments are saved according to the dwell time period identifier and the beam number, and correspond to the scanning angle grouping identifier and beam number in the alignment result. The background echo segments are used to estimate the channel drift value under the current dwell time period, and the background echo intensity benchmark value is used to determine the lower limit of the main scanning beam echo intensity in the pattern deviation segment stage. The generation time and purpose of the two are different. The background echo segments come from the same dwell time period and the same beam number of the echo sampling set, and avoid the neighborhood of the echo arrival time corresponding to the distance value, so as to reduce the proportion of the target echo intensity introduced into the channel drift estimation and reduce the probability of misrecording the target scattering change as the channel amplitude and phase consistency change.

[0099] Channel drift values ​​are estimated based on background echo segments, and channel drift values ​​corresponding to the current dwell time are generated. For the current dwell time and the background echo segments under the corresponding beam number, background echo intensity sequences are extracted by array element channel. For each array element channel's background echo intensity sequence, the value corresponding to the middle position is taken as the representative value of the array element channel's background echo intensity. Subsequently, the representative values ​​of the background echo intensity of all array element channels under the current dwell time and corresponding beam number are summarized and sorted in descending order, and the representative value of the background echo intensity corresponding to the middle position is taken as the channel reference value under the current dwell time and corresponding beam number. Finally, the representative value of the background echo intensity of each array element channel is calculated separately. The difference between the current processing dwell time identifier and the channel reference value is used as the channel drift value of the corresponding array element channel. The dwell time identifier, the corresponding beam number, and the channel drift value of each array element channel are recorded and saved to be consistent with the dwell time identifier and beam number in the alignment result. By using the channel reference value of all array element channels under the current processing dwell time and the corresponding beam number as a consistency reference, and then using the difference between the background echo intensity representative value of each array element channel and the channel reference value to characterize the channel drift value, the direct impact of transmit power fluctuation and calibration constant value difference on the channel drift value can be reduced, and the asymmetric echo power drift caused by the pattern roll-off effect masking the changes in channel amplitude and phase consistency can be reduced.

[0100] When mapping channel drift values ​​to pattern deviation segments to form scan angle group-level channel drift aggregation values, the scan angle group identifier and beam number corresponding to each channel drift value are first determined based on the alignment results. For multiple dwell time periods corresponding to the same scan angle group identifier and the same beam number, the channel drift values ​​of multiple dwell time periods are taken to form channel drift aggregation values ​​and arranged in chronological order of dwell time periods.

[0101] A channel consistency correction table is obtained based on the channel drift aggregation value and the pattern deviation segment. For each scan angle group identifier and beam number, the power difference aggregation result corresponding to the scan angle group identifier and beam number in the pattern deviation segment is read, and then the representative channel drift value of each array element corresponding to the scan angle group identifier and beam number in the channel drift aggregation value is read. The scan angle group identifier, beam number, corresponding power difference aggregation result, and corresponding representative channel drift value of each array element are recorded as a channel consistency correction table record. The above process is repeated for all scan angle group identifiers and beam numbers, and they are arranged in the order of scan angle group identifier and beam number to form a channel consistency correction table. The channel consistency correction table includes the scan angle group identifier, beam number, power difference aggregation result, and channel drift aggregation value.

[0102] The beam weighting module, based on the multi-beam pointing table, pattern deviation segment and channel consistency correction table, performs echo power compensation on the main scanning beam to obtain the drift-free echo power sequence; and obtains the maneuver decoupling weight based on the change of the tracking error sequence in adjacent dwell time periods.

[0103] To suppress asymmetric drift and pseudo-correlation of the main scanning beam echo power under beam scanning and target maneuvering conditions, this implementation performs echo power compensation on the main scanning beam echo power based on the pattern deviation segment and channel consistency correction table, obtains the drift-free echo power sequence, and determines the maneuver decoupling weight based on the change of the tracking error sequence in adjacent dwell periods.

[0104] Establish a main scanning beam echo power sequence that is consistent with the pattern deviation segment in terms of scanning angle grouping identifier and beam number; process each dwell time period according to the multi-beam pointing table in the order of dwell time, extract the beam number and main scanning beam pointing angle of the main scanning beam for each dwell time period, extract the main scanning beam echo power corresponding to the beam number from the multi-beam power group, and record the dwell time identifier, main scanning beam pointing angle, beam number and main scanning beam echo power of the currently processed dwell time period; repeat the above processing for all dwell time periods, and process them in the order of dwell time. The time intervals are arranged sequentially to form the echo power sequence of the main scanning beam. Subsequently, the scanning angle grouping and identification of the main scanning beam pointing angle are performed, and the scanning angle grouping and identification are consistent with the scanning angle grouping and identification of the pattern deviation segment. The beam number and pointing angle of the main scanning beam are determined by the multi-beam pointing table. The echo power sequence of the main scanning beam obtains a unified angle reference, reducing the impact of beam number switching and pointing angle recording differences on the consistency of echo power, thereby reducing the drift error introduced by inconsistent angle reference in the target radar cross-section estimation.

[0105] Extract the corresponding values ​​of the pattern deviation segment and channel consistency correction table according to the scan angle grouping identifier and beam number; for each dwell time period, locate the power difference aggregation result of the same scan angle grouping identifier and the same beam number in the pattern deviation segment based on the scan angle grouping identifier and the same beam number; locate the channel drift aggregation value of the same scan angle grouping identifier and the same beam number in the channel consistency correction table. The channel drift aggregation value is used to characterize the offset effect introduced by the change of array element channel amplitude consistency with the scan angle; if the scan angle grouping identifier corresponding to a certain dwell time period is not found in the pattern deviation segment or the channel consistency correction table... If it occurs, values ​​are taken along adjacent groups of the scanning angle; the dwell time identifier, scanning angle group identifier, beam number, power difference aggregation result and channel drift aggregation value are summarized according to the dwell time to form a compensation reference sequence; by extracting the power difference aggregation result and channel drift aggregation value under the same scanning angle group identifier and the same beam number, the compensation reference sequence adds the pattern asymmetric drift and the element channel amplitude consistency offset to the reference quantity of the same aperture, reducing the probability of mistaking the element channel amplitude consistency offset as the target scattering change, and reducing the angular dependence caused by pattern model error in the target radar cross-section estimation.

[0106] When performing echo power compensation on the main scanning beam echo power sequence based on the compensation reference sequence to obtain the drift-free echo power sequence, the main scanning beam echo power of the main scanning beam echo power sequence is read for each dwell time period. The power difference aggregation result and channel drift aggregation value corresponding to the same dwell time period are read from the compensation reference sequence. The power difference aggregation result is used to characterize the asymmetric influence of the left and right accompanying beams on the main scanning beam, and the channel drift aggregation value is used to characterize the offset influence introduced by the change of the scan angle of the array element channel amplitude consistency.

[0107] Within the same dwell time period, the power difference aggregation result and the channel drift aggregation value are processed to be dimensionlessly standardized. The dimensionless standardization process uses the echo power of the main scanning beam as the normalization benchmark. The proportions of the power difference aggregation result to the echo power of the main scanning beam and the proportions of the channel drift aggregation value to the echo power of the main scanning beam are calculated to obtain the power difference ratio and the channel drift ratio. Preset upper limits are set for the power difference ratio and the channel drift ratio respectively. A first upper limit is set for the power difference ratio, and a second upper limit is set for the channel drift ratio. The first upper limit is selected based on the variation range of the power difference aggregation result under the majority scanning angle grouping identifier, and the second upper limit is selected based on the variation range of the channel drift aggregation value under the majority scanning angle grouping identifier. When the power difference ratio is greater than the first upper limit, the first upper limit is used; when the channel drift ratio is greater than the second upper limit, the second upper limit is used.

[0108] The compensation direction and magnitude are then determined. The compensation direction is determined by the sign of both the power difference aggregation result and the channel drift aggregation value. When both the power difference aggregation result and the channel drift aggregation value are positive, the compensation direction is to reduce the echo power of the main scanning beam. When both the power difference aggregation result and the channel drift aggregation value are negative, the compensation direction is to increase the echo power of the main scanning beam. When the signs of the power difference aggregation result and the channel drift aggregation value are inconsistent, the compensation direction is determined based on the term with the larger absolute value ratio. The term with the larger absolute value ratio is the larger of the absolute values ​​of the power difference ratio and the channel drift ratio. The amplitude is obtained by weighting the power difference ratio and the channel drift ratio. For example, when the absolute value of the power difference ratio is more than 1.5 times the absolute value of the channel drift ratio, the preset power difference weight is 0.7 and the preset channel drift weight is 0.3; when the absolute value of the channel drift ratio is more than 1.5 times the absolute value of the power difference ratio, the preset power difference weight is 0.3 and the preset channel drift weight is 0.7; when the ratio between the absolute value of the power difference ratio and the absolute value of the channel drift ratio is between the above two cases, the preset power difference weight is 0.5 and the preset channel drift weight is 0.5.

[0109] Then, the first compensation amount is obtained by multiplying the preset power difference weight by the absolute value of the power difference ratio. The second compensation amount is obtained by multiplying the preset channel drift weight by the absolute value of the channel drift ratio. The first compensation amount and the second compensation amount are then added together to obtain the compensation amplitude ratio. By assigning clear weights to the power difference ratio and the channel drift ratio and calculating the compensation amplitude ratio in a unified order, the echo power compensation has a reproducible calculation path.

[0110] After obtaining the compensation amplitude ratio, the main scanning beam echo power correction is calculated based on the main scanning beam echo power. The main scanning beam echo power correction is the product of the main scanning beam echo power and the compensation amplitude ratio. A compensation upper limit ratio is set, selected according to the rule that it covers the range of compensation amplitude variation corresponding to the power difference aggregation result and channel drift aggregation value under most scanning angle groupings, and the compensation upper limit ratio is less than 1. The upper limit of the main scanning beam echo power correction is determined based on the main scanning beam echo power and the compensation upper limit ratio. The upper limit of the main scanning beam echo power correction is the product of the main scanning beam echo power and the compensation upper limit ratio. When the main scanning beam echo power correction exceeds the upper limit of the main scanning beam echo power correction, the main scanning beam echo power... The correction amount is limited to the upper limit of the main scanning beam echo power correction amount; the main scanning beam echo power correction amount is applied to the main scanning beam echo power according to the compensation direction to obtain the compensated echo power; the compensated echo power is sorted and summarized according to the dwell time period to obtain the de-drift echo power sequence; by mapping the power difference aggregation result and the channel drift aggregation value to the main scanning beam echo power correction amount through dimensionless conversion, weight combination and compensation direction constraint, and constrained by the preset compensation upper limit to constrain the correction amount amplitude, the echo power compensation weakens the asymmetric drift caused by the power difference between the left and right accompanying beams at the dwell time scale, weakens the pattern shape deviation caused by the amplitude consistency offset of the array element channels, and reduces the risk of asymmetric drift of echo power of the same target under different scanning angles and different beam numbers.

[0111] Please see Figure 3As shown, the decoupling weights are determined based on the changes in the tracking error sequence during adjacent dwell periods. First, the tracking error sequences are arranged according to the acquisition sequence corresponding to the dwell period identifier, ensuring a clear temporal adjacency between the current dwell period and the previous and next dwell periods. The difference between the tracking error sequences of adjacent dwell periods is extracted as the error change. The error change is divided into error change direction and error change amplitude. The error change direction is determined by the sign of the error change, and the error change amplitude is determined by the absolute value of the error change. A preset error change amplitude threshold is set, which is selected based on the rule that the preset error change amplitude threshold is not less than the quantization step size of the tracking error sequence and not greater than the angular difference between the left and right accompanying beams relative to the main scanning beam. Then, upper and lower weight limits are set. The upper weight limit is selected based on the fluctuation of the tracking error sequence during adjacent dwell periods. When the error change amplitude is close to the quantization step size of the tracking error sequence and... When the direction of error change is not consistently consistent during the continuous dwell period, the upper limit of the weight is taken as a value close to 1. When the magnitude of error change is less than or equal to the preset error change magnitude threshold but greater than the quantization step size of the tracking error sequence, the upper limit of the weight is taken as a value close to 0.7. The lower limit of the weight is selected based on the degree to which the magnitude of error change exceeds the preset error change magnitude threshold and the degree of consistency of the direction of error change during the continuous dwell period. When the magnitude of error change is greater than the preset error change magnitude threshold and the direction of error change remains consistent during the continuous dwell period, the lower limit of the weight is taken as a value close to 0.2. When the magnitude of error change is only greater than the preset error change magnitude threshold or the direction of error change is not consistent during the continuous dwell period, the lower limit of the weight is taken as a value close to 0.6. When the magnitude of error change is less than or equal to the preset error change magnitude threshold, the weight of the maneuver decoupling is taken as the upper limit of the weight. When the magnitude of error change is greater than the preset error change magnitude threshold, the weight of the maneuver decoupling is taken as the lower limit of the weight.

[0112] After determining the basic values ​​for the maneuver decoupling weights, the consistency of the error change direction within the continuous dwell time period is then assessed. Specifically, the selection rule for the number of continuous dwell time periods is preset to cover the range of dwell time periods during a single maneuver where the tracking error continuously changes in the same direction. The signs of each error change within the number of continuous dwell time periods prior to the current dwell time period are compared. When the signs of each error change are consistent, the error change direction is determined to be consistent within the continuous dwell time period, and the weight is adjusted towards the lower limit of the current maneuver decoupling weight. When the signs of each error change are inconsistent, the current maneuver decoupling weight remains unchanged. The adjusted maneuver decoupling weight is greater than or equal to the lower limit of the weight. The maneuver decoupling weight introduces adjacent changes in the tracking error sequence into the echo power processing, suppressing the component of the echo power that changes in the same direction as the maneuver direction at the weight level. This reduces the risk of false correlation between the echo power and the maneuver direction during target maneuvering and reduces the occurrence of random deviation in target radar cross-section estimation.

[0113] The system outputs indexed de-drift echo power sequences and maneuver decoupling weights. These sequences and weights are then aligned and recorded according to dwell time periods, retaining the dwell time period identifier, scan angle group identifier, and beam number during alignment. The de-drift echo power sequence provides compensated echo power values ​​for each dwell time period, and the maneuver decoupling weights provide values ​​corresponding to the error changes in adjacent dwell time periods. The de-drift echo power sequence values ​​and maneuver decoupling weights for each dwell time period are arranged in order of dwell time, forming an indexed output. The output simultaneously provides both the de-drift echo power sequence and maneuver decoupling weights at the dwell time scale. The angular drift of echo power and maneuver pseudo-correlation are separated and expressed at the data layer, reducing the sensitivity of subsequent target radar cross-section estimation to changes in scan angle and maneuver direction, and improving the comparability of the same target across scan angles and beam numbers.

[0114] The area estimation module determines the radar cross-section estimate for each dwell time period based on the drift-free echo power sequence, range value, transmit power value, and calibration constant. It then performs a weighted summation of the radar cross-section estimates for each dwell time period on the same target according to the maneuver decoupling weight to obtain the radar cross-section estimation sequence.

[0115] Determine the continuous dwell time periods for the same target and complete data alignment; specifically, sort the de-drift echo power sequence by dwell time period, sort the maneuver decoupling weight by dwell time period, sort the distance value by dwell time period, and sort the transmit power value by dwell time period.

[0116] When obtaining radar cross-section estimates for a single target during continuous loitering periods, the corresponding drift-de-echo power sequence values, range values, transmit power values, and calibration constants for each loitering period are extracted and used in the linear power domain to convert the radar cross-section estimate for that single loitering period. Specifically, the transmit power value is first used to normalize the transmit power sequence values ​​to obtain the normalized transmit power echo quantity. Then, the transmit power normalized echo quantity is compensated for round-trip propagation attenuation based on the range value. The range value is processed using the one-way propagation distance, and the propagation attenuation compensation is calculated according to the fourth power relationship of the range formed by round-trip propagation to obtain the range-compensated echo quantity. Finally, the calibration constants under the corresponding operating mode and beam number for the current loitering period are read, and the calibration constants are confirmed to correspond to... The calibration results are consistent with the digital beamforming weighted synthesis method used during the current dwell time. The calibration constant is used to characterize the amplitude correspondence between the range-compensated echo and the radar cross-section under the current operating mode and beam number. The calibration constant does not include the range value and the transmit power value. Subsequently, based on the correspondence between the range-compensated echo and the radar cross-section established in the calibration process, the range-compensated echo is converted into the radar cross-section dimension. During the conversion, when the range-compensated echo is consistent with the range-compensated echo corresponding to the calibration target, the output result corresponds to the radar cross-section of the calibration target. When the range-compensated echo increases or decreases relative to the range-compensated echo corresponding to the calibration target, the output result is adjusted synchronously according to the same correspondence to obtain the radar cross-section estimate for the current dwell time.

[0117] The calibration constants are taken from pre-established calibration results, which are established by the calibration process. The calibration process is executed during a pre-set calibration period, which is the starting time after equipment goes online, is maintained or replaced, or the operating mode is switched, and is triggered according to a pre-set update cycle. The selection rule for the pre-set update cycle is that it covers the time scale of the drift of the transmit power record and the drift of the receive link amplitude scale. In the calibration process, the radar is pointed at the calibration target, and the radar cross-section of the calibration target adopts a pre-stored standard value. The pre-stored standard value comes from the factory calibration data, metrological verification data, or pre-measured reference data of the calibration target. Subsequently, the main scanning beam, the left accompanying beam, and the right accompanying beam are formed according to the operating mode and beam number, and an echo sampling set is collected from the calibration target. Based on the echo sampling set, a multi-beam power group is obtained, and further... The values ​​of the drift-de-echo power sequence, range, and transmit power are obtained. Using the nominal value of the calibrated target as a reference for the amplitude scale, the correspondence between the range-compensated echo quantity and the radar cross-section is established, forming calibration constants. The calibration constants include the influence terms of antenna gain, wavelength, system loss, matched filter gain, and accumulation gain. The range and transmit power values ​​are used as explicit inputs in the conversion of the radar cross-section estimate for a single dwell time period, and the maneuver decoupling weights are used as explicit inputs in the weighted summation of the radar cross-section estimate sequence for continuous dwell time periods. The calibration constants are recorded separately according to the operating mode and beam number because different operating modes correspond to different pulse widths, bandwidths, and accumulation methods, and different beam numbers correspond to different digital beamforming weighted synthesis methods, which causes the amplitude scale of the drift-de-echo power sequence values ​​to change with the operating mode and beam number.

[0118] For continuous loitering periods of the same target, the radar cross-section (RCS) estimates are weighted and summed according to the maneuver decoupling weights to form an RCS estimate sequence. A preset aggregation window length is set for the continuous loitering periods of the same target. The preset aggregation window length is selected based on the number of continuous loitering periods covered by the preset aggregation window length within a single scan angle crossing process. A sliding window is used to select windows within the continuous loitering periods using the preset aggregation window length. For each sliding window, the RCS estimate and corresponding maneuver decoupling weights for each loitering period are extracted. The RCS estimate for each loitering period is multiplied by the corresponding maneuver decoupling weight to obtain the window weighted value for the current loitering period. Finally, all window weighted values ​​within the sliding window are summed to obtain the window weighted sum. The weighted sum of the window is then divided by the sum of all maneuver decoupling weights within the sliding window to obtain the weighted sum of the sliding window. When the sum of all maneuver decoupling weights within the sliding window is less than 0.5, the weighted sum of the sliding window corresponds to the midpoint of the radar cross-section estimates for each dwell time period within the window. The weighted sum of each sliding window is arranged in order of dwell time period to obtain the radar cross-section estimation sequence. By constraining the contribution of the radar cross-section estimates for each dwell time period with the normalized proportion of the maneuver decoupling weights within the continuous dwell time period, the asymmetric drift residue caused by the combined effect of scanning angle changes and tracking error sequence changes can be reduced, and the deviation of the radar cross-section estimation sequence due to random maneuvering direction changes can be reduced.

[0119] The radar cross section (RCS) estimation sequence undergoes continuous dwell time boundary processing. For continuous dwell time of the same target, if the preset aggregation window length cannot completely cover the available dwell time near the boundary of the continuous dwell time, the preset aggregation window length is shortened to the window length corresponding to the number of available dwell time at the boundary. The selection rule for the shortened preset aggregation window length is that the shortened preset aggregation window length is not less than 2 dwell time periods, consistent with the number of available dwell time periods near the boundary of the continuous dwell time. The RCS estimates at the boundary are still weighted and summed according to the maneuver decoupling weight to obtain the boundary result. The boundary result is then connected with the weighted summation result corresponding to the middle position according to the dwell time sequence to form a complete RCS estimation sequence. By using the shortened preset aggregation window length at the boundary of the continuous dwell time, the continuous expression of the RCS estimation sequence at the boundary can be maintained, reducing the impact of sequence breaks caused by boundary window gaps on the consistency of target scattering characteristic characterization.

[0120] Example 2

[0121] Please see Figure 2 As shown, this embodiment provides a target radar cross-section estimation method, including:

[0122] During each dwell period, a main scanning beam, a left accompanying beam, and a right accompanying beam are formed. Echo samples are collected from the array element channels to obtain an echo sampling set. The beam number and pointing angle of each beam are recorded to obtain a multi-beam pointing table. The tracking error sequence, distance value, transmit power value, and calibration constant are obtained. The multi-beam power group is obtained from the intensity of the main scanning beam, the left accompanying beam, and the right accompanying beam.

[0123] The power difference between the left and right accompanying beams is calculated based on the multi-beam power group and the multi-beam pointing table to obtain the pattern deviation segment.

[0124] Align the pattern deviation segment with the echo sampling set, select the background echo segment to estimate the channel drift value, and map the channel drift value to the pattern deviation segment to obtain the channel consistency correction table.

[0125] Based on the multi-beam pointing table, pattern deviation segment and channel consistency correction table, echo power compensation is performed on the main scanning beam to obtain the drift-free echo power sequence; the maneuver decoupling weight is obtained based on the change of the tracking error sequence in adjacent dwell time periods.

[0126] Based on the drift-de-echo power sequence, range value, transmit power value, and calibration constant, the radar cross-section estimate corresponding to each dwell time period is determined. The radar cross-section estimate of each dwell time period is weighted and summed according to the maneuver decoupling weight during the continuous dwell time periods of the same target to obtain the radar cross-section estimate sequence.

[0127] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for estimating the radar cross-section of a target, characterized in that, include: During each dwell period, a main scanning beam, a left-side accompanying beam, and a right-side accompanying beam are formed. Echo samples from the array element channels are collected to obtain an echo sample set. The beam number and pointing angle of each beam are recorded to obtain a multi-beam pointing table. The tracking error sequence, distance value, transmit power value and calibration constant are obtained, and the multi-beam power group is obtained from the intensity of the main scanning beam, the left accompanying beam and the right accompanying beam; Based on the multibeam power group and the multibeam pointing table, the radiation pattern deviation segment is calculated; After aligning the pattern deviation segment with the echo sampling set, select the background echo segment; The channel drift value is estimated based on the background echo segment, and the channel drift value is mapped to the pattern deviation segment to obtain the channel consistency correction table; Based on the multi-beam pointing table, pattern deviation segment and channel consistency correction table, echo power compensation is performed on the main scanning beam to obtain the drift-free echo power sequence; the maneuver decoupling weight is obtained based on the change of the tracking error sequence in adjacent dwell time periods. Based on the drift-de-echo power sequence, range value, transmit power value, and calibration constant, the radar cross-section estimate corresponding to each dwell time period is determined. The radar cross-section estimate of each dwell time period is weighted and summed according to the maneuver decoupling weight during the continuous dwell time periods of the same target to obtain the radar cross-section estimate sequence.

2. The target radar cross-section estimation method according to claim 1, characterized in that, Methods for obtaining distance values ​​and multibeam power groups include: The time difference between the start time of the dwell period and the arrival time of the echo is extracted from the echo sampling set, and the distance value is calculated based on the time difference. Within a preset time interval before and after the echo arrival time, the echo intensity of the main scanning beam, the left accompanying beam, and the right accompanying beam are extracted to obtain the multi-beam power group.

3. The target radar cross-section estimation method according to claim 2, characterized in that, Methods for obtaining pattern deviation segments include: Extract the beam number and pointing angle from the multi-beam pointing table, and calculate the power difference sequence from the echo intensity of the left accompanying beam and the echo intensity of the right accompanying beam in the multi-beam power group. The scanning angle is recorded using the pointing angle of the main scanning beam. The scanning angle records are grouped according to a preset angle step size to obtain the scanning angle group identifier. The power difference sequence is aggregated according to the scanning angle grouping identifier and beam number to obtain the pattern deviation segment.

4. The target radar cross-section estimation method according to claim 3, characterized in that, Methods for obtaining the channel consistency correction table include: Based on the multi-beam pointing table, the beam number and pointing angle of the main scanning beam are extracted according to the dwell time period, and the pointing angle is assigned to the scanning angle grouping identifier of the pattern deviation segment to obtain the alignment result; Based on the alignment results, a preset time interval before and after the arrival time of the echo is determined within the echo sampling set, and a candidate background interval is selected outside the preset time interval before and after the arrival time of the echo to obtain the background echo segment. The channel drift aggregation value is obtained based on the background echo segment, and the channel drift aggregation value is aligned with the pattern deviation segment according to the scanning angle grouping identifier and beam number to obtain the channel consistency correction table.

5. The target radar cross-section estimation method according to claim 4, characterized in that, Methods for obtaining channel drift aggregation values ​​based on background echo segments include: The background echo intensity sequence is extracted by the array element channel, and the value in the middle position after arranging the background echo intensity sequence according to the numerical value is taken as the representative value of the background echo intensity. After summarizing the representative values ​​of the background echo intensity of each array element channel, sort them in descending order, and use the representative value of the background echo intensity in the middle position as the channel reference value. The difference between the representative value of the background echo intensity of each array element channel and the channel reference value is used as the channel drift value; The channel drift values ​​corresponding to the same scan angle group identifier and the same beam number are aggregated to obtain the aggregated channel drift value.

6. The target radar cross-section estimation method according to claim 4, characterized in that, Methods for obtaining drift-free echo power sequences include: Extract the echo power of the main scanning beam from the multi-beam power group, locate the power difference aggregation result in the pattern deviation segment according to the scanning angle grouping identifier and beam number, and locate the channel drift aggregation value in the channel consistency correction table; Using the echo power of the main scanning beam as a normalization benchmark, the power difference aggregation result and the channel drift aggregation value are processed to be dimensionless to determine the compensation direction and compensation amplitude. The echo power of the main scanning beam is then compensated according to the compensation direction and compensation amplitude to obtain the drift-free echo power sequence.

7. The target radar cross-section estimation method according to claim 6, characterized in that, Methods for obtaining the maneuver decoupling weights include: The tracking error sequence is sorted by dwell time period, and the difference between adjacent dwell time periods is extracted to obtain the direction and magnitude of error change; The range of values ​​for the maneuver decoupling weight is determined based on the magnitude of error change and the preset threshold for the magnitude of error change, and the maneuver decoupling weight is adjusted based on the consistency of the direction of error change within the preset number of continuous dwell periods.

8. The target radar cross-section estimation method according to claim 7, characterized in that, Methods for determining the radar cross-section estimate for each stay period include: The drift-de-echo power sequence, distance value, and transmit power value are sorted by dwell time period; For each dwell period, the transmit power value is first used to normalize the drift echo power sequence value, then the round-trip propagation attenuation compensation is performed based on the distance value, and converted with the calibration constant to obtain the radar cross-section estimate value corresponding to each dwell period.

9. A target radar cross-section estimation method according to claim 2, characterized in that... Methods for obtaining echo intensity include: The digital beamforming weighted synthesis method is determined based on the beam number and pointing angle of the multi-beam pointing table. The digital beamforming weighted synthesis method is the set of weighting coefficients for each array element channel. The echo samples of each array element channel are weighted and synthesized according to the weighted coefficient set to obtain the beam echo sampling sequence. The sum of the squared amplitudes of the beam echo sampling sequence is then normalized according to the number of sampling points to obtain the echo intensity.

10. The target radar cross-section estimation method according to claim 1, characterized in that, The calibration constants are taken from the calibration results of the calibration process; The calibration process includes: pointing the radar at the calibration target to form the main scanning beam, the left accompanying beam and the right accompanying beam; collecting the echo sampling set to obtain the multi-beam power group, the drift-de-echo power sequence value, the range value and the transmit power value; and establishing the corresponding relationship based on the radar cross-section of the calibration target to form the calibration constant.

11. The target radar cross-section estimation method according to claim 8, characterized in that, Methods for obtaining radar cross-section estimation sequences include: For the continuous dwell time of the same target, a preset aggregation window length is set. During the continuous dwell time, the window is slid-selected, and the radar cross-section estimate within the sliding window is weighted and summed according to the proportion of the maneuver decoupling weight to the sum of all maneuver decoupling weights within the window. For continuous dwell time periods, the preset aggregation window length is shortened according to the set shortening rules, and the radar cross-section estimates within the sliding window are weighted and summed according to the maneuver decoupling weights to obtain the radar cross-section estimate sequence.

12. A target radar cross-section estimation system, used to implement the target radar cross-section estimation method according to any one of claims 1-11, characterized in that, include: The beam acquisition module is used to form the main scanning beam, the left accompanying beam, and the right accompanying beam during each dwell period. It acquires echo samples from the array element channels to obtain an echo sample set, records the beam number and pointing angle of each beam to obtain a multi-beam pointing table, and obtains the tracking error sequence, distance value, transmit power value, and calibration constant. It also obtains the multi-beam power group from the intensity of the main scanning beam, the left accompanying beam, and the right accompanying beam. The beam deviation module calculates the pattern deviation segment based on the multi-beam power group and the multi-beam pointing table. The beam correction module is used to align the pattern deviation segment with the echo sampling set and then select the background echo segment. The channel drift value is estimated based on the background echo segment, and the channel drift value is mapped to the pattern deviation segment to obtain the channel consistency correction table; The beam weighting module, based on the multi-beam pointing table, pattern deviation segment, and channel consistency correction table, performs echo power compensation on the main scanning beam to obtain the drift-free echo power sequence; and obtains the maneuver decoupling weight based on the changes in the tracking error sequence during adjacent dwell periods. The area estimation module determines the radar cross-section estimate for each dwell time period based on the drift-free echo power sequence, range value, transmit power value, and calibration constant. It then performs a weighted summation of the radar cross-section estimates for each dwell time period on the same target according to the maneuver decoupling weight to obtain the radar cross-section estimation sequence.

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