A method and device for time-frequency domain two-dimensional sliding window demodulation of medium-heavy frequency PD radar

Abstract

This application provides a two-dimensional sliding window deambiguation method and apparatus in the time-frequency domain for medium-repetition-frequency (MRF) PD radar. The method includes: Step 1, extending the range points formed by the multi-repetition-frequency periodic radar echoes within the observation range in both range and velocity dimensions to determine all possible position and velocity information of the target; Step 2, quantizing the observation area using set quantization unit parameters, and marking all targets in a nine-square grid; Step 3, sequentially performing sliding window detection on the quantized and marked observation area in a grid pattern, and determining the existence of the target using the M / N detection criterion; Step 4, for targets detected and determined in Step 3, extracting target information based on the maximum amplitude criterion, and clearing the marker of the target's observation area to zero. This application significantly reduces the difficulty and computational load of deambiguation, and by utilizing range and velocity information, it also reduces the generation of false points.

Description

Technical Field

[0001] This application relates to the field of radar signal processing technology, and in particular to a two-dimensional sliding window deambiguation method and apparatus for medium-repetition-rate (MRPR) PD radar in the time and frequency domain. Background Technology

[0002] Pulse Doppler (PD) technology, with its excellent clutter suppression performance, is currently widely used in various radar equipment. Compared with low and high repetition rate (PRR) modes, mid-PRR mode radar echoes exhibit both range and velocity ambiguity in both range and Doppler dimensions, and are also affected by range and velocity blind zones.

[0003] To eliminate ambiguity and obstruction issues, radar systems generally employ a multi-frequency staggered operation mode. The challenge in deambiguing a medium-repetition-frequency (MRF) PD radar system lies in how to reliably and accurately calculate the target's true position and velocity information.

[0004] Traditional algorithms are limited to number theory calculations in a single dimension, failing to utilize the most important characteristic information of PD radar—Doppler frequency. Moreover, the reliability, accuracy, and computational complexity of the solution are greatly affected by the algorithm. Summary of the Invention

[0005] This application provides a two-dimensional sliding window deambiguation method and apparatus for medium-repetition-frequency (PD) radar in the time-frequency domain, which can be used to solve the technical problem that traditional algorithms do not utilize the most important feature information of PD radar - the Doppler frequency.

[0006] This application provides a two-dimensional sliding window deambiguation method in the time-frequency domain for medium-repetition-rate (MR) PD radar, the method comprising:

[0007] Step 1: Extend the range point traces formed by the multi-frequency periodic radar echoes within the observation range in both range and velocity dimensions to determine all possible position and velocity information of the target;

[0008] Step 2: Quantize the observation area using the set quantization unit parameters, and mark all targets in a "nine-square grid" manner.

[0009] Step 3: Perform sliding window detection on the quantized and marked observation areas in a grid pattern, and determine the existence of the target using the "M / N" detection criterion;

[0010] Step 4: Based on the detection and determination of the existing target in Step 3, extract the target information according to the maximum amplitude criterion, and clear the label of the observation area of ​​this target to zero.

[0011] Furthermore, in step 1, the range point traces formed by the multi-frequency periodic radar echoes are extended in both range and velocity dimensions within the observation range to determine all possible position and velocity information of the target, including:

[0012] Step 11: Given that the parameters for each period of the radar multi-frequency stagger are PRT_1, PRT_2…PRT_N, the maximum unambiguous range for each period is:

[0013] RanBlind_N = PRT_N * C / 2, where C is the speed of light;

[0014] The distance between the dots is:

[0015] Plot_Ran=Plot_Ran_Vision+k*RanBlind_N,

[0016] Where Plot_Ran_Visio is the apparent distance of the point, and k is the expansion factor, which is an integer;

[0017] Step 12, based on the radar multi-frequency staggered period parameters, the maximum unambiguous velocity for each period is:

[0018] VelBlind_N = λ / (2*PRT_N),

[0019] Where λ is the radar operating wavelength, and the point velocity is:

[0020] Plot_Vel=Plot_Vel_Vision+k*VelBlind_N

[0021] Where Plot_Vel_Vision is the apparent velocity of the point, k is the expansion factor, and k is an integer.

[0022] Furthermore, the observation area is quantized using the set quantization unit parameters, and all targets are marked in a "nine-square grid" manner, including:

[0023] Step 21: Set the quantization unit parameters according to the radar performance requirements. Assuming the maximum observation range of the radar observation area is Detect_Ran_Max, the maximum observation velocity is Detect_Vel_Max, the radar beam dwell time is Time_Dwell, and the sampling rate is Fs, then the range quantization unit parameter Thelta_Ran satisfies:

[0024]

[0025] The velocity quantization unit parameter Thelta_Vel satisfies:

[0026]

[0027] Step 22: Mark all target points obtained in Step 1 using a "3x3 grid":

[0028] Calculate the distance marker index for each point, Plot_Ran_Index = round(Plot_Ran / Thelta_Ran), where Plot_Ran is the point distance, and the velocity marker index for each point, Plot_Vel_Index = round(Plot_Vel / Thelta_Vel), where Plot_Vel is the point velocity.

[0029] Then, the index area [Plot_Ran_Index-1:Plot_Ran_Index+1,Plot_Vel_Index-1:Plot_Vel_Index+1] is marked, and the index area is the "nine-square grid".

[0030] Furthermore, the M / N detection criterion means that N refers to the number of radar multi-frequency staggered cycles, and M refers to the detection threshold for the number of times the target appears in the radar staggered cycle echo. Both N and M are integers, and M ≤ N. If the target appears in M ​​or more radar staggered cycle echoes within N radar multi-frequency staggered cycles, then the target is determined to exist. For example, to illustrate the "2 / 4" detection criterion, the number of radar multi-frequency staggered cycles is 4. When the target appears in 2 or more radar staggered cycle echoes simultaneously...

[0031] Furthermore, a sliding window detection is performed sequentially on the quantized and marked observation area using a grid pattern, and the presence of the target is determined using the "M / N" detection criterion, including:

[0032] The grid-like sliding window method means that if the current detection point coordinates are [m,n], then [m+1,n], [m,n+1] and [m+1,n+1] are used as joint judgment conditions. Only when all four coordinate markers in the grid meet the M / N criterion are the corresponding positions determined to be the true target points.

[0033] This application also provides a time-frequency domain two-dimensional sliding window deambiguation device for a medium-repetition-rate PD radar, the device comprising:

[0034] The determination module is used to extend the range point traces formed by multi-frequency periodic radar echoes within the observation range in both range and velocity dimensions to determine all possible positions and velocities of the target.

[0035] The marking module is used to quantize the observation area with the set quantization unit parameters, and mark all targets in a "nine-square grid" manner.

[0036] The judgment module is used to perform sliding window detection on the quantized and marked observation area in a grid pattern, and determine whether the target exists based on the "M / N" detection criterion.

[0037] The zeroing module is used to detect and determine the existence of targets, extract target information based on the maximum amplitude criterion, and clear the marker of the target's observation area to zero.

[0038] Furthermore, the module is specifically used for:

[0039] If the parameters for each period of the multi-frequency staggered radar are PRT_1, PRT_2, ..., PRT_N, then the maximum unambiguous range for each period is:

[0040] RanBlind_N = PRT_N * C / 2, where C is the speed of light;

[0041] The distance between the dots is:

[0042] Plot_Ran=Plot_Ran_Vision+k*RanBlind_N,

[0043] Where Plot_Ran_Visio is the apparent distance of the point, and k is the expansion factor, which is an integer;

[0044] Based on the radar's multi-frequency staggered period parameters, the maximum unambiguous velocity for each period is:

[0045] VelBlind_N = λ / (2*PRT_N),

[0046] Where λ is the radar operating wavelength, and the point velocity is:

[0047] Plot_Vel=Plot_Vel_Vision+k*VelBlind_N

[0048] Where Plot_Vel_Vision is the apparent velocity of the point, k is the expansion factor, and k is an integer.

[0049] Furthermore, the tagging module is specifically used for:

[0050] Based on the radar performance requirements, the quantization unit parameters are set. Assuming the maximum observation range of the radar observation area is Detect_Ran_Max, the maximum observation velocity is Detect_Vel_Max, the radar beam dwell time is Time_Dwell, and the sampling rate is Fs, then the range quantization unit parameter Thelta_Ran satisfies:

[0051]

[0052] The velocity quantization unit parameter Thelta_Vel satisfies:

[0053]

[0054] All target points are marked using a 3x3 grid:

[0055] Calculate the distance marker index for each point, Plot_Ran_Index = round(Plot_Ran / Thelta_Ran), where Plot_Ran is the point distance, and the velocity marker index for each point, Plot_Vel_Index = round(Plot_Vel / Thelta_Vel), where Plot_Vel is the point velocity.

[0056] Then, the index area [Plot_Ran_Index-1:Plot_Ran_Index+1,Plot_Vel_Index-1:Plot_Vel_Index+1] is marked, and the index area is the "nine-square grid".

[0057] Furthermore, the M / N detection criterion means that N refers to the number of radar multi-frequency staggered cycles, and M refers to the detection threshold for the number of times the target appears in the radar staggered cycle echo. N and M are both integers and M≤N. If M or more radar staggered cycle echoes appear within N radar multi-frequency staggered cycles, the target is determined to exist. For example, to illustrate the "2 / 4" detection criterion, the number of radar multi-frequency staggered cycles is 4. When the target appears simultaneously in 2 or more radar staggered cycle echoes, the target is determined to exist.

[0058] Furthermore, the judgment module is specifically used for:

[0059] The grid sliding window method means that if the current detection point coordinates are [m,n], then [m+1,n], [m,n+1] and [m+1,n+1] are used as joint judgment conditions. Only when all four coordinate labels in the grid meet the M / N criterion are they judged as the real target point.

[0060] Compared with existing technologies, the significant advantages of this invention are: (1) It adopts a two-dimensional quantization method for radar detection area range and velocity, which can simultaneously resolve range and velocity ambiguities, with low computational load and universality and practicality. (2) Targets are clustered and identified in a "nine-square grid" manner, increasing the margin for target deambiguation while reducing the difficulty of deambiguation. (3) It adopts the "M / N" detection criterion and uses a sliding window detection method in a "grid" manner, effectively reducing the generation of false targets. Attached Figure Description

[0061] Figure 1 A flowchart illustrating the implementation of a two-dimensional sliding window deambiguation method in the time-frequency domain for a mid-repetition-rate PD radar, as provided in this application embodiment;

[0062] Figure 2 This application provides a blind zone coverage map under the 2 / 4 detection criterion with 4 repetition cycles in an embodiment of the present application.

[0063] Figure 3 This is a schematic diagram of the "nine-square grid" marking provided in the embodiments of this application;

[0064] Figure 4 This is a schematic diagram of the "grid" sliding window detection provided in an embodiment of this application. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0066] This invention proposes a two-dimensional sliding window deambiguation method in the time-frequency domain for medium-repetition-frequency (MRF) PD radar. When the radar adopts the MRF staggered operation mode, it can simultaneously perform deambiguation calculations on target range and velocity, while ensuring high reliability and low computational load in deambiguation. This method has certain reference value for the engineering implementation of pulse Doppler technology.

[0067] The present application is further illustrated below through specific embodiments.

[0068] The radar parameters were simulated using MATLAB software, with wavelength λ = 0.1, pulse width Tr = 10 μs, and 4-repetition-rate staggered period PRT_N = [287121203164] μs. The maximum radar observation range was set to Detect_Ran_Max of 120 km, and the maximum speed was set to Detect_Vel_Max = 500 m / s. The simulated target parameters were set to a range of 90 km and a speed of 300 m / s.

[0069] In step 1, the range point traces formed by the multi-frequency radar echoes are extended in both range and velocity dimensions within the observation range to calculate the position and velocity information of all possible target points. The specific implementation method is as follows:

[0070] Step 11: Calculate the maximum unambiguous distance RanBlind_N for each cycle based on the PRT_N parameter and the speed of light parameter. The result is [86100, 36300, 60900, 49200] m. The apparent distance of the simulated target in each staggered cycle is:

[0071] Plot_Ran_Visio_N = [3900, 17400, 0, 40800] m. In the fourth cycle, the target is in the velocity blind zone, so there is no target in this cycle. The distance of the spot is extended within the detection range in three staggered cycles. The distances of the spot formed in the four staggered cycles are: Plot_Ran_Tmp1 = [3900, 90000] m, Plot_Ran_Tmp2 = [17400, 53700, 90000] m, and Plot_Ran_Tmp4 = [40800, 90000] m.

[0072] Step 12: Calculate the maximum unambiguous velocity (VelBlind_N) based on the simulation wavelength λ and the staggered period PRT_N parameter as [174.2, 413.2, 246.3, 304.9] m / s. The apparent velocity of the simulated target in each staggered period is Plot_Vel_Visio_N as [125.78, -113.22, 53.7, 0] m / s. The target is in the velocity blind zone in the 4th period, therefore there is no target in that period. The same applies to the 3rd period onwards. In each staggered period, the points are extended at a velocity within the detection range, resulting in point velocities of: Plot_Vel_Tmp1 = [-396.87, -222.65, -48.44, 125.78, 300.0, 474.21] m / s, Plot_Vel_Tmp2 = [-113.22, 300.0] m / s, and Plot_Vel_Tmp3 = [-438.9, -192.6, 53.7, 300] m / s.

[0073] Step 2 involves quantizing the observation area using the set quantization unit parameters, and simultaneously marking all targets calculated in Step 1 using a "nine-square grid". The specific implementation steps are as follows:

[0074] Step 21: Set the quantization unit parameters according to the radar performance requirements. The radar beam dwell time is Time_Dwell = 12400us. Based on the constraints, the range quantization parameters Thelta_Ran = 10m and Thelta_Vel = 5m / s can be set. Taking the radar position and the minimum velocity boundary as the quantization center, the observation area has a maximum range dimension of 120km, corresponding to a quantization region of [0, 12000]. The velocity range is [-1000, 1000], with a quantization region of [0, 400]. Therefore, the range-velocity quantization region of the observation area is [12000, 400]. The horizontal axis represents range, and the vertical axis represents velocity.

[0075] Step 22: Based on the calculations in Step 1, the number of plots formed by the target in the first period (plot_num1) is 2 * 6 = 12; the number of plots formed by the target in the second period is 3 * 2 = 6; and the number of plots formed by the target in the third period is 2 * 4 = 8. The total number of plots is 26. The index Plot_Ran_Index corresponding to each plot is calculated as ([390, -79], [9000, -79], [390, -45], [9000, -45], [390, -10], [9000, -10], [390, 25], [9000, 25]). [390, 60], [9000, 60], [390, 95], [9000, 95], [1740, -23], [5370, -23], [9000, -23], [1740, 60], [5370, 60], [9000, 60], [4080, -88], [9000, -88], [4080, -39], [9000, -39], [4080, 11], [9000, 11], [4080, 60], [9000, 60], and so on, mark all the points in the observation area in the form of a "nine-square grid".

[0076] In step 3, the "M / N" criterion is set to 2 / 4. Only when all point markers within the "grid" satisfy the "M / N" criterion is it determined that a target point exists there. Finally, the marker at the quantization region [8999:9001, 59:61] is 3, which satisfies the judgment criterion and is determined to be a target point.

[0077] Step 4: Based on the target location area [8999:9001, 200:202] determined in Step 3, extract the target's true information using the maximum amplitude of the point trace in the three cycles as the criterion, clear the quantized area's identifier, and continue with Step 3 to find the target point.

[0078] This application significantly reduces the difficulty and computational load of deambiguation, while also reducing the generation of false dots by utilizing distance and velocity information. The method presented in this application has advantages such as low computational cost, high versatility, and strong practicality, and can be well applied to the engineering implementation of deambiguation in medium-repetition-rate (NRFR) PD radar.

[0079] The embodiments described above do not constitute a limitation on the scope of protection of this application.

Claims

1. A two-dimensional sliding window deambiguation method in the time-frequency domain for medium-repetition-rate (MRF) PD radar, characterized in that, The method includes: Step 1: Extend the range point traces formed by the multi-frequency periodic radar echoes within the observation range in both range and velocity dimensions to determine all possible position and velocity information of the target; Step 2: Quantize the observation area using the set quantization unit parameters, and mark all targets in a "nine-square grid" manner. Step 3: Perform sliding window detection on the quantized and marked observation areas in a grid pattern, and determine the existence of the target using the "M / N" detection criterion; Step 4: Based on the detection and determination of the target in Step 3, extract the target information according to the maximum amplitude criterion, and clear the marker of the observation area of ​​this target to zero; A sliding window detection is performed sequentially on the quantized and marked observation area using a grid pattern, and the presence of the target is determined using the "M / N" detection criterion, including: The grid-like sliding window method means that if the current detection point coordinates are [m,n], then [m+1,n], [m,n+1] and [m+1,n+1] are used as joint judgment conditions. Only when all four coordinate markers in the grid meet the M / N criterion are the corresponding positions determined to be the true target points.

2. The method according to claim 1, characterized in that, In step 1, the range point traces formed by the multi-frequency periodic radar echoes are extended in both range and velocity dimensions within the observation range to determine all possible position and velocity information of the target, including: Step 1-1: Given that the parameters for each period of the radar multi-frequency stagger are PRT_1, PRT_2…PRT_N, the maximum unambiguous range for each period is: RanBlind_N = PRT_N * C / 2, where C is the speed of light; The distance between the dots is: Plot_Ran=Plot_Ran_Vision+k*RanBlind_N, Where Plot_Ran_Visio is the apparent distance of the point, and k is the expansion factor, which is an integer; Steps 1-2: Based on the radar's multi-frequency staggered period parameters, the maximum unambiguous velocity for each period is: VelBlind_N = λ / (2*PRT_N), Where λ is the radar operating wavelength, and the point velocity is: Plot_Vel=Plot_Vel_Vision+k*VelBlind_N Where Plot_Vel_Vision is the apparent velocity of the point, k is the expansion factor, and k is an integer.

3. The method according to claim 1, characterized in that, The observation area is quantized using the set quantization unit parameters, and all targets are marked in a "nine-square grid" format, including: Step 2-1: Set the quantization unit parameters according to the radar performance requirements. Assuming the maximum observation range of the radar observation area is Detect_Ran_Max, the maximum observation velocity is Detect_Vel_Max, the radar beam dwell time is Time_Dwell, and the sampling rate is Fs, then the range quantization unit parameter Thelta_Ran satisfies: The velocity quantization unit parameter Thelta_Vel satisfies: Step 2-2: Mark all target points obtained in Step 1 using a "3x3 grid" method: Calculate the distance marker index for each point, Plot_Ran_Index = round(Plot_Ran / Thelta_Ran), where Plot_Ran is the point distance, and the velocity marker index for each point, Plot_Vel_Index = round(Plot_Vel / Thelta_Vel), where Plot_Vel is the point velocity. Then, the index area [Plot_Ran_Index-1:Plot_Ran_Index+1,Plot_Vel_Index-1:Plot_Vel_Index+1] is marked, and the index area is the "nine-square grid".

4. The method according to claim 1, characterized in that, The M / N detection criterion means that N refers to the number of radar multi-frequency staggered cycles, and M refers to the detection threshold for the number of times the target appears in the radar staggered cycle echo. N and M are both integers and M≤N. If M or more radar staggered cycle echoes appear within N radar multi-frequency staggered cycles, the target is determined to exist.

5. A two-dimensional sliding window deambiguation device in the time-frequency domain for a medium-repetition-rate (MRF) PD radar, characterized in that, The device includes: The determination module is used to extend the range point traces formed by multi-frequency periodic radar echoes within the observation range in both range and velocity dimensions to determine all possible positions and velocities of the target. The marking module is used to quantize the observation area with the set quantization unit parameters, and mark all targets in a "nine-square grid" manner. The judgment module is used to perform sliding window detection on the quantized and marked observation area in a grid pattern, and determine whether the target exists based on the "M / N" detection criterion. The zeroing module is used to detect and determine the existence of targets, extract target information based on the maximum amplitude criterion, and clear the marker of the observation area of ​​this target to zero. Specifically, the judgment module is used for: The grid sliding window method means that if the current detection point coordinates are [m,n], then [m+1,n], [m,n+1] and [m+1,n+1] are used as joint judgment conditions. Only when all four coordinate labels in the grid meet the M / N criterion are they judged as the real target point.

6. The apparatus according to claim 5, characterized in that, The module is specifically used for: If the parameters for each period of the multi-frequency staggered radar are PRT_1, PRT_2…PRT_N, then the maximum unambiguous range for each period is: RanBlind_N = PRT_N * C / 2, where C is the speed of light; The distance between the dots is: Plot_Ran=Plot_Ran_Vision+k*RanBlind_N, Where Plot_Ran_Visio is the apparent distance of the point, and k is the expansion factor, which is an integer; Based on the radar's multi-frequency staggered period parameters, the maximum unambiguous velocity for each period is: VelBlind_N = λ / (2*PRT_N), Where λ is the radar operating wavelength, and the point velocity is: Plot_Vel=Plot_Vel_Vision+k*VelBlind_N Where Plot_Vel_Vision is the apparent velocity of the point, k is the expansion factor, and k is an integer.

7. The apparatus according to claim 5, characterized in that, The tagging module is specifically used for: Based on the radar performance requirements, the quantization unit parameters are set. Assuming the maximum observation range of the radar observation area is Detect_Ran_Max, the maximum observation velocity is Detect_Vel_Max, the radar beam dwell time is Time_Dwell, and the sampling rate is Fs, then the range quantization unit parameter Thelta_Ran satisfies: The velocity quantization unit parameter Thelta_Vel satisfies: All target points are marked using a "3x3 grid": Calculate the distance marker index for each point, Plot_Ran_Index = round(Plot_Ran / Thelta_Ran), where Plot_Ran is the point distance, and the velocity marker index for each point, Plot_Vel_Index = round(Plot_Vel / Thelta_Vel), where Plot_Vel is the point velocity. Then, the index area [Plot_Ran_Index-1:Plot_Ran_Index+1,Plot_Vel_Index-1:Plot_Vel_Index+1] is marked, and the index area is the "nine-square grid".

8. The apparatus according to claim 5, characterized in that, The M / N detection criterion means that N refers to the number of radar multi-frequency staggered cycles, and M refers to the detection threshold for the number of times the target appears in the radar staggered cycle echo. N and M are both integers and M≤N. If M or more radar staggered cycle echoes appear within N radar multi-frequency staggered cycles, the target is determined to exist.

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