A high-speed target detection method based on a two-phase encoding signal spaceborne measurement radar

Abstract

A high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals comprises the following steps: 1. Dividing the target detection process into stages; 2. Dividing the range segments according to radar detection range requirements to obtain multiple range modes; 3. Classifying the speed according to radar velocity measurement requirements; 4. Determining the priority of range mode selection during full-range mode search and the priority of speed level selection during full-speed level search; 5. Developing search strategies and search-to-tracking strategies for each range mode; 6. Developing speed selection and update strategies when calculating the phase increment of the target echo using Doppler compensation during the target search stage; 7. Developing speed selection and update strategies when calculating the phase increment of the target echo using Doppler compensation during the target tracking stage; 8. Continuously tracking and measuring the target to obtain target information. This invention effectively solves the problem of high-speed target detection, is not limited by radar system, and has a wide range of applications.

Description

Technical Field

[0001] This invention relates to the field of spaceborne measurement radar signal processing technology, specifically to a high-speed target detection method for spaceborne measurement radar based on binary phase-coded signals. Background Technology

[0002] As the application scenarios in the field of space science become increasingly complex, higher and higher requirements are being placed on the target detection capabilities of satellite payloads. Not only are low-speed moving targets required, but the need to detect high-speed moving targets is also becoming increasingly prominent.

[0003] Binary phase-coded signals possess excellent autocorrelation characteristics, but they are highly sensitive to the Doppler frequency of moving targets. As the target's speed increases, the received binary phase-coded echo signal easily mismatches with the matched filter, causing a sharp deterioration in pulse compression and rendering effective target detection impossible. In a DSP and FPGA architecture, the DSP calculates the phase increment in real time, and the FPGA performs Doppler compensation on the binary phase-coded echo signal based on the DSP's calculated phase increment. This effectively solves the problem of mismatch between the binary phase-coded signal and the matched filter when performing pulse compression on the echo signal from high-speed targets, providing a theoretical possibility for spaceborne measurement radar to use binary phase-coded signals to detect high-speed targets.

[0004] Based on the above theory, the key to whether a spaceborne measurement radar using binary phase-coded signals can detect high-speed targets lies in whether the correct target velocity can be used to calculate the phase increment and effectively compensate for the target echo during the target detection process. The velocity used to calculate the phase increment is crucial for effectively pulse-compressing the echo of a target moving at a speed close to that velocity, thus enabling effective detection of targets moving at that speed. However, for non-cooperative targets, the target velocity information is unknown, making effective Doppler compensation for the target echo during target detection extremely difficult. Therefore, designing a high-speed target detection method based on binary phase-coded signals for spaceborne measurement radar is of great application value and practical significance for the fully autonomous detection of space targets using binary phase-coded signal-based spaceborne measurement radar.

[0005] It is understood that the above statements only provide background information related to the present invention and do not necessarily constitute prior art. Summary of the Invention

[0006] The purpose of this invention is to provide a high-speed target detection method based on a binary phase-coded signal spaceborne measurement radar. This method can effectively solve the problem of high-speed target detection by spaceborne measurement radar using a binary phase-coded signal system. It eliminates the need for guidance information from other systems, enabling the spaceborne measurement radar to autonomously detect non-cooperative targets. Furthermore, this invention has no requirements on the radar system; it is applicable to any spaceborne measurement radar using a binary phase-coded signal system, whether it is a phased array or mechanically scanned system, thus having a wide range of applications.

[0007] To achieve the above objectives, this invention provides a high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals, specifically comprising the following steps:

[0008] S1. Divide the target detection process into stages;

[0009] S2. Divide the range segments according to the radar detection range requirements to obtain multiple range modes, and determine the range modes that need range deblurring processing.

[0010] S3. According to the radar speed measurement requirements, the speed is divided into speed levels by constructing a speed compensation array to obtain multiple speed levels. The speed level can be selected by selecting different elements in the speed compensation array.

[0011] S4. Determine the priority of distance mode selection when searching in full-distance mode; and determine the priority of speed gear selection when searching in full-speed gear.

[0012] S5. Develop search strategies and search-to-tracking strategies for each distance mode;

[0013] S6. Formulate the velocity selection and update strategy when calculating the phase increment of the Doppler compensation for the target echo during the target search phase;

[0014] S7. Formulate the velocity selection and update strategy when calculating the phase increment of the Doppler compensation for the target echo during the target tracking phase;

[0015] S8. Continuously track and measure the target and obtain target information.

[0016] Furthermore, in S1, the entire target detection process is divided into two stages: target search and target tracking, using a spaceborne measurement radar. The target search stage is mainly responsible for discovering and intercepting targets in the airspace, while the target tracking stage keeps the radar beam locked on the target, tracks and measures the target, and outputs target measurement information.

[0017] Among them, whether to switch from the target search stage to the target tracking stage is determined based on whether the switching conditions are met.

[0018] Furthermore, the condition for transitioning from the target search phase to the target tracking phase is: whether there are 6 consecutive frames of target interception within 10 consecutive frames.

[0019] Furthermore, S2 specifically includes the following steps:

[0020] S21. Based on the requirements for radar detection range, the range from the closest detection range to the farthest detection range is divided into several range segments, and each range segment corresponds to a range mode.

[0021] S22. Combine the unambiguous range of each range segment with the radar's maximum effective range to determine the range pattern that will be affected by range ambiguity.

[0022] S23. For the distance patterns obtained in S22 that are affected by distance blurring, determine that they need to be deblurred. All distance patterns that need to be deblurred are collectively referred to as near distance patterns, and distance patterns that do not need to be deblurred are collectively referred to as far distance patterns.

[0023] Furthermore, in S3, the lower limit of the speed required by radar speed measurement is used as the first element of the speed compensation array, and subsequent elements are generated sequentially according to the requirement that each subsequent element is 20 m / s higher than the previous element. When the difference between a generated element and the upper limit of the speed measurement requirement is within 20 m / s, this element is used as the last element of the speed compensation array.

[0024] Furthermore, in S4, the priority principle is: prioritize searching for targets with a higher degree of danger.

[0025] Furthermore, in S5, the search airspace designated by the radar is divided into several wave positions, each wave position is encoded, and each wave position is searched sequentially according to the encoding order; during the target search process, when a target is intercepted at a certain wave position, regardless of whether the current range mode requires range deambiguity, the beam is pointed to stop at the current wave position to confirm the target.

[0026] Furthermore, in S6, a compensation velocity matching the target velocity is used to calculate the phase increment and perform effective Doppler compensation on the target echo.

[0027] Furthermore, in S7, during the target tracking phase, the selection and update strategy for calculating the phase increment needs to be divided into three stages:

[0028] S71, after entering the target tracking phase and before the target speed is measured;

[0029] S72. After the target speed is measured and during stable tracking;

[0030] S73, during the period after the distance mode is switched during the tracking process.

[0031] In S71, the speed used to calculate the phase increment when performing Doppler compensation is consistent with the speed used to calculate the phase increment when performing Doppler compensation during the target search phase before tracking.

[0032] In S72, if the change in the measured true velocity of the target relative to the velocity used to calculate the phase increment during Doppler compensation does not exceed the set velocity change threshold, then the velocity used to calculate the phase increment during Doppler compensation is not updated; otherwise, the measured true velocity of the target is used to update the velocity used to calculate the phase increment during Doppler compensation.

[0033] In S73, to prevent the use of incorrect target velocities calculated under the new range mode for Doppler compensation after the range mode switch, which could lead to pulse compression failure of echo data and loss of the target, the velocity used to calculate the phase increment during Doppler compensation is not updated during the stable tracking phase and for a period of time after the range mode switch. Once the target velocity calculated under the new range mode is determined to be stable, the velocity value used to calculate the phase increment during Doppler compensation is updated using the true target velocity calculated under the new range mode.

[0034] In summary, compared with the prior art, the high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals of the present invention has the following beneficial effects:

[0035] (1) This invention provides a high-speed target detection method based on binary phase-coded signals, which can effectively solve the problem of high-speed target detection by spaceborne measurement radar based on binary phase-coded signal system;

[0036] (2) This invention enables the spaceborne measurement radar to no longer require guidance information provided by other systems, and enables the spaceborne measurement radar to autonomously detect non-cooperative targets;

[0037] (3) The variable repetition frequency resolution range ambiguity operation designed in this invention can effectively avoid the influence of range ambiguity during the target detection process of spaceborne measurement radar;

[0038] (4) This invention enables the speed measurement capability of the spaceborne measurement radar to be adjustable. By modifying the content and number of elements in the speed compensation array, the upper and lower limits of the radar's ability to detect the speed of targets can be changed to a certain extent. It is simple to operate and easy to implement.

[0039] (5) This invention does not require a specific radar system. As long as it is a spaceborne measurement radar that uses two-phase coded signals, it is applicable regardless of whether it is a phased array system or a mechanically scanned system. It has a wide range of applications. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the specific process of the present invention;

[0041] Figure 2 This is a flowchart illustrating the search and search-to-tracking strategies for different distance modes in this invention.

[0042] Figure 3 This is a flowchart illustrating the velocity selection and update strategy during the phase increment calculation phase of this invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figure 1 As shown in the figure, this is a schematic flowchart of a high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals according to the present invention, which specifically includes the following steps:

[0045] S1. Divide the target detection process into stages;

[0046] S2. Divide the range segments according to the radar detection range requirements to obtain multiple range modes, and determine the range modes that need range deblurring processing.

[0047] S3. According to the radar speed measurement requirements, the speed is divided into speed levels by constructing a speed compensation array to obtain multiple speed levels. The speed level can be selected by selecting different elements in the speed compensation array.

[0048] S4. Determine the priority of distance mode selection when searching in full-distance mode; and determine the priority of speed gear selection when searching in full-speed gear.

[0049] S5. Develop search strategies and search-to-tracking strategies for each distance mode;

[0050] S6. Formulate the velocity selection and update strategy when calculating the phase increment of the Doppler compensation for the target echo during the target search phase;

[0051] S7. Formulate the velocity selection and update strategy when calculating the phase increment of the Doppler compensation for the target echo during the target tracking phase;

[0052] S8. Continuously track and measure the target and obtain target information.

[0053] Furthermore, in S1, the entire target detection process is divided into two stages: target search and target tracking, using a spaceborne measurement radar. The target search stage is mainly responsible for discovering and intercepting targets in the airspace, while the target tracking stage keeps the radar beam locked on the target, tracks and measures the target, and outputs target measurement information. The transition from the target search stage to the target tracking stage is determined based on whether the transition condition is met. This condition is whether the target is continuously intercepted in 6 out of 10 consecutive frames.

[0054] Furthermore, S2 specifically includes the following steps:

[0055] S21. Based on the requirements for radar detection range in the mission requirements, the range from the closest detection range to the farthest detection range will be divided into several range segments, and each range segment will correspond to a range mode.

[0056] S22. Combine the unambiguous range of each range segment with the radar's maximum effective range to determine the range pattern that will be affected by range ambiguity.

[0057] S23. For the distance patterns obtained in S22 that are affected by distance blurring, they are identified as needing distance deblurring. All distance patterns that need distance deblurring are collectively referred to as near-distance patterns, and all distance patterns that do not need distance deblurring are collectively referred to as far-distance patterns.

[0058] The division of range segments is part of the radar system parameter design and is related to parameters such as pulse width, repetition rate, and number of pulses accumulated for each range mode. The division of range segments requires theoretical simulation. The principle is to ensure that the divided range modes, from near to far, can cover the entire range detection range required in the mission statement. Furthermore, the two range modes must be effectively connected without omitting any range segments. The division of range segments must be set by the user based on the specific parameters of the product.

[0059] In a preferred embodiment of the present invention, taking the ranging requirement of 1km to 70km for the spaceborne measurement radar in the mission requirements as an example, the range of 1km to 70km is divided into four range segments, each corresponding to a range mode. Specifically, the range of 1km to 10km is range mode 0, the range of 10km to 30km is range mode 1, the range of 30km to 60km is range mode 2, and the range of 60km to 70km is range mode 3. Range mode 0 uses a pulse repetition frequency of 5kHz, range mode 1 uses a pulse repetition frequency of 3kHz, range mode 2 uses a pulse repetition frequency of 2kHz, and range mode 3 uses a pulse repetition frequency of 1kHz. Therefore, the unambiguous ranges corresponding to range modes 0, 1, 2, and 3 are 30km, 49.95km, 75km, and 150km, respectively. Considering the mission requirement of a maximum radar range of 70km, range modes 0 and 1 will be affected by range ambiguity during target detection, while range modes 2 and 3 will not. Therefore, range modes 0 and 1 require range deambiguation processing during target detection and are collectively referred to as short-range modes, while range modes 2 and 3 do not require deambiguation processing and are collectively referred to as long-range modes. When searching for targets, each range mode searches for targets within that range mode. By traversing all four range modes, it is possible to detect whether there are targets within the radar ranging range requirement in the specified airspace.

[0060] Furthermore, in S3, the lower limit of the radar speed measurement requirement is used as the first element of the speed compensation array. Subsequent elements are generated sequentially according to the requirement that each subsequent element increases by 20 m / s compared to the previous element. When the difference between a generated element and the upper limit of the speed measurement requirement is within 20 m / s, this element is used as the last element of the speed compensation array. Each element in the speed compensation array corresponds to a speed level, and the number of elements in the speed compensation array is the number of speed levels after speed grading. By grading speeds, when searching for targets, each speed level can be searched to find targets with speeds near that speed level. By traversing and searching all speed levels, it is possible to detect whether there are targets with speeds within the speed measurement requirement range in the specified airspace.

[0061] In a preferred embodiment of the present invention, taking the speed measurement requirement of the spaceborne measurement radar in the mission requirements as -150m / s to 150m / s as an example, the speed is divided into levels by constructing a speed compensation array. The lower limit of the speed measurement requirement, -150m / s, is taken as the first element of the speed compensation array. Each subsequent element is increased by 20m / s compared to the previous element, and so on. Then the complete speed compensation array is velo_compensate_array

[16] ={-150, -130, -110, -90, -70, -50, -30, -10, 10, 30, 50, 70, 90, 110, 130, 150}. Each element in the speed compensation array corresponds to a speed level. Through speed leveling, a total of 16 speed levels are generated, which are sequentially denoted as speed level 0, speed level 1, speed level 2... speed level 15. When searching for a target, each speed level is searched one by one. After traversing and searching all 16 speed levels, it is possible to detect whether there is a target with a speed in the range of -150m / s to 150m / s in the specified airspace.

[0062] After dividing the range into S2 range segments and S3 into S3 speed range segments, the presence of targets within the speed range requirement can be detected across the entire radar ranging range by searching in both range mode and speed range. Therefore, determining the priority of range mode selection during range mode search and the priority of speed range selection during speed range search is crucial. Generally, targets with higher speeds are considered more dangerous, targets closer to the target are more dangerous, and targets that are closer to the target are more dangerous than those that are farther away.

[0063] Furthermore, in S4, the priority of distance mode selection during full-distance mode search and the priority of speed gear selection during full-speed gear search are determined according to the principle of prioritizing the search for targets with higher risk levels.

[0064] Specifically, when performing a full-range mode search, the distance mode covering the closest distance segment is searched first, followed by the distance mode covering the next closest distance segment, and so on, with the distance mode covering the furthest distance segment being searched last; when performing a full-speed gear search, the highest approach speed gear is searched first, followed by the next highest approach speed gear, and so on, with the lowest approach speed gear being searched last.

[0065] In a preferred embodiment of the invention, following the principle of prioritizing the search for targets with higher danger levels, the search proceeds from near to far during the full-range mode search. Specifically, targets within the range corresponding to range mode 0 are searched first, followed by targets within the range corresponding to range mode 1, then targets within the range corresponding to range mode 2, and finally targets within the range corresponding to range mode 3. Furthermore, targets with negative speeds are considered approaching targets, and targets with positive speeds are considered distant targets. Combining this with the speed compensation array, during the full-speed range search, targets with speeds around -150 m / s are searched first, followed by targets with speeds around -130 m / s, and so on, until targets with speeds around 150 m / s are finally searched. Similarly, the search proceeds in the order of speed range 0, then speed range 1, then speed range 2, and so on, until speed range 15 is finally searched, until all 16 speed ranges have been traversed.

[0066] Furthermore, in practical applications, it is necessary to combine the full-distance pattern search and the full-speed gear search together. For example, according to the priority search order of the speed gear, in the first speed gear, all distance patterns are traversed and searched according to the priority search order of the distance patterns. Then, switch to the next speed gear and traverse and search all distance patterns again, and so on, until switch to the last speed gear and traverse and search all distance patterns. Therefore, in a preferred embodiment of the present invention, the search is first performed at speed setting 0, following the priority order of searching for range mode 0, then range mode 1, then range mode 2, and finally range mode 3. Then, the search is switched to speed setting 1, and the priority order of searching for range mode 0, then range mode 1, then range mode 2, and finally range mode 3 is repeated. Finally, at speed setting 15, the search is performed again following the priority order of searching for range mode 0, then range mode 1, then range mode 2, and finally range mode 3. At each speed setting, all range modes are searched in order from near to far until all speed settings have been traversed according to their priority order. By traversing and searching all speed settings and all range modes at each speed setting, the system detects whether there are targets with speeds within the required range of the entire radar ranging requirement.

[0067] Furthermore, such as Figure 2As shown, in S5, the overall (mission requirements) search airspace assigned to the radar is divided into several wave positions. Each wave position is encoded, and each wave position is searched sequentially according to the encoding order. During the target search process, in order to prevent the target from being outside the beam illumination range due to changes in beam pointing during the variable repetition rate processing and range de-ambiguation processing in the close-range mode, thus affecting the range de-ambiguation, a target confirmation step is added after the target is acquired. Specifically, when a target is acquired at a certain wave position, regardless of whether the current range mode requires range de-ambiguation, the beam pointing is stopped at the current wave position for target confirmation.

[0068] In the full-range and full-speed search processes, the target is searched sequentially for each beacon position within a specific speed and range mode. If a target is acquired at a beacon position and the current range mode is short-range, variable repetition frequency (RPF) processing is performed to determine if the acquired target has range ambiguity. If range ambiguity exists, the accurate target range is obtained through range deambiguation, the range mode is switched to the range mode corresponding to that accurate range, and the target is searched again at that beacon position. If the target is not acquired at a beacon position, the search continues to the next beacon position. Furthermore, if the target is acquired again during the re-search, it is determined whether the target meets the switching-to-tracking condition. If the switching-to-tracking condition is met, the target is tracked and measured. If the target is not acquired after switching to the range mode corresponding to that accurate range, or if the target is acquired but the switching-to-tracking condition is not met, the control beam is directed sequentially to the next remaining beacon position according to the beacon position code to search for the target, until all beacons within the overall specified airspace have been searched.

[0069] If the current range mode is long-range mode when the target is intercepted, the long-range mode is limited by the radar's maximum effective range. There is no range ambiguity in the long-range mode, so there is no need for variable repetition frequency processing and range deambiguity processing. It directly determines whether the switching to tracking condition is met. If the switching to tracking condition is met, it switches to tracking the target and measures the target. If the switching to tracking condition is not met, it controls the beam to point to the next remaining position in sequence to search for the target until all positions in the overall specified airspace have been searched.

[0070] In a preferred embodiment of the present invention, the overall search area is divided into several wave positions according to the overall search center and search range. Taking the overall search center angle (0°, 0°) and search range (10°, 10°) for azimuth and elevation dimensions as an example, assuming that the overall specified airspace centered at azimuth 0° and elevation 0°, with azimuth ranging from -10° to 10° and elevation ranging from -10° to 10°, is divided into 50 wave positions according to beamwidth and beam overlap rate, the 50 wave positions are sequentially encoded as wave position 0, wave position 1...wave position 49, and the search is performed sequentially at each wave position in ascending order of wave position number.

[0071] Specifically, assuming a full-range, full-speed search is being conducted, currently at speed level 0 and range mode 0, and a target is intercepted during the search of the airspace corresponding to beam position 0, the beam is immediately stopped at the current beam position for target confirmation. Since the current range mode is 0, according to step 2, range mode 0 requires repetition frequency (RF) adjustment to determine if the target has range ambiguity. If, after using the new RF parameters, the position of the maximum value of the range dimension corresponding to the target changes, it indicates that the target has range ambiguity. If range ambiguity exists, the true target distance needs to be determined by calculating the range ambiguity order. Further, taking an example where the target distance before RF adjustment is 8 kilometers and the range ambiguity order is 1, the calculated true target distance is 38 kilometers, indicating that the target is within the range segment corresponding to range mode 2. Therefore, the range mode is switched to range mode 2 and the search is restarted. If the target is intercepted again, the condition for switching to tracking is determined based on whether there are 6 consecutive interceptions within 10 frames. If the condition is met, target tracking is switched; otherwise, the beam is controlled to sequentially point to beam position 2, beam position 3, and so on, until beam position 49 is searched. If switching the range mode to range mode 2 and re-searching fails to effectively capture the target, similarly control the beam to point to position 2, position 3, and so on until position 49 is searched.

[0072] Furthermore, in S6, the method of calculating the phase increment in real time to perform Doppler compensation on the target echo enables the spaceborne measurement radar with a binary phase-coded signal system to also detect high-speed targets. Its essence lies in using a compensation velocity that matches the target velocity to calculate the phase increment and effectively compensate the target echo for Doppler. During the target search phase, searching for a target at a certain speed level allows detection of targets with speeds near that speed level. By searching in a speed segment-by-segment manner, i.e., by traversing all speed levels, full coverage of target detection across the entire speed range is achieved. Therefore, during the target search phase, when searching for a target at a certain speed level, the speed value of the corresponding level in the speed compensation array is used as the compensation velocity for calculating the phase increment of the target echo for Doppler compensation. When traversing all speed levels to detect targets across the entire speed range, the 0th element, the 1st element, ..., and so on, of the speed compensation array are used sequentially until the last element is reached as the compensation velocity for calculating the phase increment of the target echo for Doppler compensation.

[0073] In a preferred embodiment of the present invention, during the target search phase, when searching for a target at a certain speed level, the speed value corresponding to that speed level in the speed compensation array is used as the compensation speed for calculating the phase increment of the target echo using Doppler compensation. According to the implementation described herein, when searching for a target at speed level 0, -150 m / s is used as the compensation speed for calculating the phase increment of the target echo using Doppler compensation; when searching for a target at speed level 1, -130 m / s is used as the compensation speed; and so on. For example, when searching for a target at speed level 15, 150 m / s is used as the compensation speed for calculating the phase increment of the target echo using Doppler compensation.

[0074] Furthermore, such as Figure 3 As shown, in S7, during the target tracking phase, the selection and update strategy for calculating the phase increment needs to be considered in three stages: S71, before the target velocity is measured after entering the target tracking phase; S72, during the stable tracking process after the target velocity is measured; and S73, during a period of time after the distance mode is switched during the tracking process.

[0075] Specifically, in S71, after entering the target tracking stage but before the target velocity is measured, the speed used to calculate the phase increment when performing Doppler compensation is consistent with the speed used to calculate the phase increment when performing Doppler compensation during the target search stage before switching to tracking.

[0076] Furthermore, in S72, after entering the target tracking stage and during the stable tracking process after the target velocity has been measured, a velocity change threshold is set. The purpose of this velocity change threshold is to ensure that the velocity used to calculate the phase increment during Doppler compensation closely follows the changes in the target's true velocity. Specifically, if the change in the currently measured target's true velocity relative to the velocity used to calculate the phase increment during Doppler compensation does not exceed the set velocity change threshold, the velocity used to calculate the phase increment during Doppler compensation is not updated. Otherwise, the velocity used to calculate the phase increment during Doppler compensation is updated using the currently measured target's true velocity, ensuring that the velocity used to calculate the phase increment during Doppler compensation of the target echo always closely follows the changes in the target's true velocity.

[0077] Furthermore, in S73, during the stable tracking phase, as the target moves, it inevitably encounters situations requiring a change in range mode. For a period after the range mode switch during stable tracking, due to differences in repetition rate parameters and system delays used by different range modes, there will be significant differences in the target velocity calculated by the two range modes during the mode switch. To prevent the use of the incorrect target velocity calculated under the new range mode for Doppler compensation after the range mode switch, which could lead to echo data pulse compression failure and target loss, the velocity used to calculate the phase increment during Doppler compensation is not updated for a period after the stable tracking phase and range mode switch. Only after the target velocity calculated under the new range mode is determined to be stable is the velocity value used to update the phase increment during Doppler compensation updated to the true target velocity calculated under the new range mode. The specific time required for the target velocity to be stably output under the new range mode needs to be determined based on the specific system design.

[0078] In a preferred embodiment of the present invention, during the target tracking phase, the selection and update strategy for calculating the phase increment needs to be considered in three stages. Based on the characteristics of the measuring radar, it generally takes a period of time after switching to the target tracking phase before the target's accurate velocity can be measured. During the period between entering the target tracking phase and before the target velocity is measured, the velocity used for calculating the phase increment by performing Doppler compensation on the target echo still uses the velocity value corresponding to the velocity level in the target search phase before switching to tracking. For example, taking the interception of the target and switching to tracking during speed level 0 and range mode 2 search, then after entering the target tracking phase and before the target velocity is measured... During the period before the target velocity is measured, the velocity value used to calculate the phase increment is -150 m / s. During stable tracking and after the target velocity is measured, a velocity change threshold is set. If the change in the currently measured true target velocity relative to the velocity used to calculate the phase increment during Doppler compensation exceeds the set velocity change threshold, the velocity value used to calculate the phase increment is updated with the currently measured true target velocity. Conversely, if the change in the currently measured true target velocity relative to the velocity used to calculate the phase increment during Doppler compensation does not exceed the set velocity change threshold, the velocity value used to calculate the phase increment is not updated. According to the implementation method described in this article, if the speed change threshold is set to 4 m / s, after the target is acquired and switched to tracking at speed setting 0, the measured true speed of the target is -140 m / s, and the relative speed change is 10 m / s, which exceeds the set speed change threshold of 4 m / s. Therefore, the speed value used to calculate the phase increment during Doppler compensation is updated to -140 m / s. During target tracking, if the target speed fluctuates but the speed change is less than 4 m / s, the speed value used to calculate the phase increment during Doppler compensation is not updated and remains unchanged at -140 m / s. If the target speed fluctuates and the measured target speed becomes -134 m / s, then the current Doppler compensation is... The velocity value used to calculate the phase increment is updated to -134 m / s, thus ensuring that the velocity used to calculate the phase increment when performing Doppler compensation on the target echo can always closely change with the actual velocity of the target. During the stable tracking phase, as the target moves, it will inevitably encounter situations where the range mode needs to be switched. During the stable tracking process, for a period of time after the range mode is switched, due to the differences in the repetition frequency parameters and system delays used by different range modes, there will be a large difference in the target velocity calculated by the two range modes before and after the mode switch. To prevent the use of the incorrect target velocity calculated under the new range mode for Doppler compensation after the range mode switch, which would cause the echo data pulse compression to fail and the target to be lost.During the stable tracking phase and for a period after the range mode switch, the velocity used to calculate the phase increment during Doppler compensation is not updated. In accordance with the implementation method described in this paper, after tracking the target in range mode 2, since the target is near velocity level 0, as the target moves closer, it inevitably switches from range mode 2 to range mode 1. The repetition frequency parameter of range mode 2 is 2 kHz, and that of range mode 1 is 3 kHz. Taking the range differential velocity method as an example, the measured and calculated target velocity may increase by a factor of 1.5 during the switch from range mode 2 to range mode 1. For example, if the target velocity measured during range mode 2 tracking is -150 m / s, then the velocity measured during the switch to range mode 3 will be... The target velocity will become -225 m / s. Since the change in the measured true target velocity relative to the velocity used to calculate the phase increment during Doppler compensation far exceeds the set velocity change threshold of 4 m / s, updating the velocity used to calculate the phase increment to -225 m / s will cause Doppler compensation of the target echo to fail, resulting in ineffective pulse compression and target loss. To prevent this, during the range mode switching process in the target tracking phase, frame counting is used to ensure that the velocity value used to calculate the phase increment is not updated for several frames after the range mode switch. This ensures that the true and stable target velocity value is calculated in the new range mode before updating the velocity value used to calculate the phase increment with the measured target velocity value. The specific number of frames needs to be determined based on the actual project design.

[0079] Furthermore, in S8, during the target tracking phase, the beam always locks onto the target, continuously tracks and measures the target, and outputs the target's distance, speed, and angle information.

[0080] In summary, this invention provides a high-speed target detection method based on a binary phase-coded signal spaceborne measurement radar. This method effectively solves the problem of detecting high-speed targets using a binary phase-coded signal spaceborne measurement radar, eliminating the need for guidance information from other systems and enabling autonomous detection of non-cooperative targets. Furthermore, this invention is not limited to any particular radar system; it is applicable to any spaceborne measurement radar using binary phase-coded signals, regardless of whether it is a phased array or mechanically scanned array, thus having a wide range of applications.

[0081] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals, characterized in that, Specifically, it includes the following steps: S1. Divide the target detection process into stages; In S1, the entire target detection process is divided into two stages: target search and target tracking, using a spaceborne measurement radar. The target search stage is mainly responsible for discovering and intercepting targets in the airspace, while the target tracking stage keeps the radar beam locked on the target, tracks and measures the target, and outputs target measurement information. The transition from the target search stage to the target tracking stage is determined based on whether the transition conditions are met. S2. Divide the range segments according to the radar detection range requirements to obtain multiple range modes, and determine the range modes that need range deblurring processing. S3. According to the radar speed measurement requirements, the speed is divided into speed levels by constructing a speed compensation array to obtain multiple speed levels. The speed level can be selected by selecting different elements in the speed compensation array. S4. Determine the priority of distance mode selection when searching in full-distance mode; and determine the priority of speed gear selection when searching in full-speed gear. S5. Develop search strategies and search-to-tracking strategies for each distance mode; In S5, the search airspace designated by the radar is divided into several wave positions, each wave position is encoded, and each wave position is searched in sequence according to the encoding order; during the target search process, when a target is intercepted at a certain wave position, regardless of whether the current range mode requires range deambiguity, the beam is pointed to stop at the current wave position to confirm the target. S6. Formulate the velocity selection and update strategy when calculating the phase increment of the Doppler compensation for the target echo during the target search phase; S7. Formulate the velocity selection and update strategy when calculating the phase increment of the Doppler compensation for the target echo during the target tracking phase; S8. Continuously track and measure the target and obtain target information.

2. The high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals as described in claim 1, characterized in that, The condition for transitioning from the target search phase to the target tracking phase is: whether the target is continuously captured in 6 out of 10 consecutive frames.

3. The high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals as described in claim 1, characterized in that, S2 specifically includes the following steps: S21. Based on the requirements for radar detection range, the range from the closest detection range to the farthest detection range is divided into several range segments, and each range segment corresponds to a range mode. S22. Combine the unambiguous range of each range segment with the radar's maximum effective range to determine the range pattern that will be affected by range ambiguity. S23. For the distance patterns obtained in S22 that are affected by distance blurring, determine that they need to be deblurred. All distance patterns that need to be deblurred are collectively referred to as near distance patterns, and distance patterns that do not need to be deblurred are collectively referred to as far distance patterns.

4. The high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals as described in claim 1, characterized in that, In S3, the lower limit of the speed required by radar speed measurement is used as the first element of the speed compensation array, and subsequent elements are generated sequentially according to the requirement that each subsequent element is 20 m / s higher than the previous element. When the difference between a generated element and the upper limit of the speed requirement is within 20 m / s, this element is used as the last element of the speed compensation array.

5. The high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals as described in claim 1, characterized in that, In S4, the priority principle is: prioritize searching for targets with a higher degree of danger.

6. The high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals as described in claim 1, characterized in that, In S6, the phase increment is calculated using a compensation velocity that matches the target velocity, and effective Doppler compensation is performed on the target echo.

7. The high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals as described in claim 1, characterized in that, In S7, during the target tracking phase, the selection and update strategy for calculating the phase increment needs to be divided into three stages: S71, after entering the target tracking phase and before the target speed is measured; S72. After the target speed is measured and during stable tracking; S73, during the period after the distance mode is switched during the tracking process.

8. The high-speed target detection method based on a spaceborne measurement radar with binary phase-coded signals as described in claim 7, characterized in that, In S71, the speed used to calculate the phase increment when performing Doppler compensation is consistent with the speed used to calculate the phase increment when performing Doppler compensation during the target search phase before tracking. In S72, if the change in the currently measured true target velocity relative to the velocity used to calculate the phase increment during Doppler compensation does not exceed the set velocity change threshold, then the velocity used to calculate the phase increment during Doppler compensation will not be updated; otherwise, the velocity used to calculate the phase increment during Doppler compensation will be updated using the currently measured true target velocity. In S73, to prevent the use of incorrect target velocities calculated in the new range mode for Doppler compensation after the range mode switch, which could lead to pulse compression failure of echo data and loss of the target, the velocity used to calculate the phase increment during Doppler compensation is not updated during the stable tracking phase and for a period of time after the range mode switch. Once the target velocity calculated in the new range mode is determined to be stable, the velocity value used to calculate the phase increment during Doppler compensation is updated using the true target velocity calculated in the new range mode.

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