Dual-band weak target detection method based on Hough transformation

Abstract

The invention discloses a dual-frequency-band weak target detection method based on Hough transformation, and the method comprises the following steps: S1, selecting wave beams of two frequency bands of a radar, carrying out the alignment of the wave beams of the two frequency bands in space and time, and scanning a target region; s2, acquiring echo data of wave beams of two frequency bands, and respectively setting an initial detection threshold to carry out target initial detection; s3, performing wide constraint detection on the two groups of echo data subjected to preliminary detection in the step S2 by adopting pre-installed information, and screening out detection units conforming to motion feature constraints; s4, performing dual-frequency fusion detection on the detection units screened out in the S3 based on Hough transformation, and determining a target point in a parameter domain transformation spectrum after Hough transformation; s5, for the target point determined in the S4, using Hough inverse transformation to output each dimension measurement value; the method is high in efficiency, and the detection performance is stable when the external interference noise condition changes greatly.

Description

Technical Field

[0001] The invention relates to the field of radar signal detection, and in particular to a dual-band weak target detection method based on Hough transform. Background Art

[0002] With the rapid development of electronic warfare technology and stealth technology, the detection of stealth targets in complex battlefield environments has become the main problem of precision guidance. At present, due to system limitations, the single-mode detection system has many shortcomings and it is almost difficult to meet the combat needs of future battlefields. Existing weak target detection methods, such as patents CN103777187B and CN101216554B, only consider single-frame detection and have large calculations. They are inefficient and the detection performance is not stable when the external interference noise conditions change greatly.

[0003] Dual-band compound is a typical form of multi-mode compound weak target detection, among which the dual-band active system has great advantages in the independence of target detection and the flexibility of anti-interference strategy. In addition, the dual-band composite seeker also has advantages in the detection of stealth targets that the single-mode system does not have.

[0004] The effective range of a radar seeker is determined by the various parameters of the radar equation. In order to improve the detection performance of stealth targets, single-mode radar detection usually adopts methods such as increasing the peak power of the transmitter, improving the antenna efficiency, increasing the duty cycle, reducing the noise coefficient and reducing the system loss to increase the effective range of the radar. Some relevant scholars also study how to increase the coherent accumulation time to achieve the purpose of improving the sensitivity of the seeker.

[0005] In order to meet the requirements of accurate target detection and tracking weapons in attack and defense confrontation under complex electromagnetic environment, the development of multi-mode composite guided target detection and tracking technology through information fusion has become an important direction of current precision guidance. The dual-band active composite radar works in two frequency bands at the same time, giving full play to the working advantages of the two frequency bands, and can effectively improve the target detection and tracking performance. In view of this, it is necessary to propose a dual-band weak target detection method to improve the target detection efficiency and improve its detection stability.

[0006] The statements herein merely provide background art related to the present invention and do not necessarily constitute prior art. Summary of the invention

[0007] The purpose of the present invention is to propose a dual-band weak target detection method based on Hough transform, so as to improve the target detection efficiency and keep the detection performance stable when the external interference noise conditions change greatly.

[0008] To achieve the above object, the present invention proposes a dual-band weak target detection method based on Hough transform, comprising the following steps:

[0009] S1. Select the two frequency bands of the radar beams, align the two frequency bands beams in space and time, and scan the target area;

[0010] S2, obtaining the echo data of the beams of the two frequency bands, and setting the initial detection thresholds respectively for initial target detection;

[0011] S3, for the two groups of echo data after the preliminary detection in S2, respectively use the pre-installed information to perform wide constraint detection, and select the detection units that meet the motion feature constraints;

[0012] S4, for the detection units selected by S3, dual-frequency fusion detection is performed based on Hough transform, and the target point is determined in the parameter domain transform spectrum after Hough transform;

[0013] S5. For the target point determined in S4, Hough inverse transform is used to output the measurement values ​​of each dimension.

[0014] Preferably, step S1 specifically includes: aiming beams of two frequency bands at the target area at the same time, and using the same timestamp as the start time for scanning.

[0015] Preferably, in step S2, for the two sets of echo data, the initial detection threshold is set by combining a fixed threshold with CFAR detection to perform initial detection, and detection units in the two sets of echo data that are smaller than the corresponding initial detection threshold are excluded.

[0016] Preferably, the initial detection threshold is in, Among them, α is the threshold coefficient, To estimate the interference power, x i is the power of the i-th detection unit, and N is the number of detection units.

[0017] Preferably, in step S3, the target distance limit, speed limit and acceleration limit in two adjacent frames are selected as the motion feature constraints of the target.

[0018] Preferably, the speed limit is the speed limit of the target movement, which is V min ≤V i ≤V max , where V i is the velocity of the target in the i-th frame, V min is the theoretical minimum speed of the target movement, V max is the theoretical maximum speed of the target motion; the acceleration limit is the acceleration limit value of the target motion, which is

[0019] |a i |≤a max , where a max is the acceleration limit of the target motion, a i is the acceleration of the target in the i-th frame; the target distance between two adjacent frames is limited to ΔR min ≤ΔR i,i+1 ≤ΔR max , ΔR i,i+1 is the distance difference between the target in the i-th frame and the i+1-th frame, ΔR min is the minimum theoretical distance of the target's movement in two adjacent frames,

[0020] ΔR max is the maximum theoretical distance of the target's movement in two adjacent frames, T is the time interval between two adjacent frames.

[0021] Preferably, step S4 comprises the following steps:

[0022] S41, performing parameter domain Hough transform on the two groups of echo data respectively, mapping the echo signal from the frequency-time domain to the distance-velocity domain according to the parameter domain transform method, and then fusing the distance-velocity domain spectra of different frequency bands into the same coordinate system to generate a parameter domain transform spectrum;

[0023] S42, for the parameter domain transform spectrum, grid division is performed according to the distance resolution and the velocity resolution, and the grid point intensity y is calculated. i Fill the grid;

[0024] S43, calculate the intensity threshold y of the grid r , and compare y i and r , thereby determining the target point.

[0025] Preferably, the grid point strength y i The calculation steps are as follows: take N frames from the radar scanning results of the two frequency band beams, and the grid point intensity y i The value is 0≤y i ≤X,y i =α1N1+α2N2, where X is the maximum number of detectable targets, α1 is the specific weighted value of the first frequency band, n1 is the number of lines of the first frequency band that fall into the grid, α2 is the specific weighted value of the second frequency band, and n2 is the number of lines of the second frequency band that fall into the grid. R1 and R2 are the maximum detection distances of the first and second frequency bands respectively under the detection system parameters.

[0026] Preferably, in step S43, if y i <y r , it means there is no target, if y i ≥y r , it means there is a goal.

[0027] Compared with the prior art, the technical solution of the present invention has the following advantages and beneficial effects:

[0028] This scheme proposes a dual-band weak target detection method based on Hough transform, which uses dual-frequency multi-frame data to change in the parameter domain and uses a specific weighted method to identify the detection target; uses distance resolution and speed resolution to grid the parameter domain transformation spectrum after Hough transform, calculates the intensity of each grid point after specific weight derivation, and compares each grid intensity with the grid threshold under the detection system to identify the target; This scheme first performs preliminary screening before target identification, which can greatly reduce the data to be identified. This method is highly efficient, and the detection performance is relatively stable when the external interference noise conditions change greatly; Compared with single-frequency Hough transform detection, this method reduces the false alarm rate under the same signal detection probability;

[0029] This solution expands the traditional single-band Hough transform target detection to dual-band fusion detection, making its detection performance higher and the detection accuracy better, and overcoming the problems of insufficient detection accuracy and poor efficiency of traditional algorithms;

[0030] This scheme obtains the dual-band specific weights by detecting system parameters, and obtains the dual-band weighted grid strength in each grid, which is used to determine whether there is a target in the grid. Dual-band fusion eliminates more false alarm points compared to single-band, so that under the same detection probability, dual-band fusion detection often requires a smaller signal-to-noise ratio. Dual-band fusion detection increases the maximum detection distance of the radar, and at the same time, makes the received signal strength greater during the weak target detection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a dual-band weak target detection method based on Hough transform according to an embodiment of the present invention;

[0032] Figure 2 It is a schematic diagram of generating a parameter domain transformation spectrum based on two sets of echo data in an embodiment of the present invention;

[0033] Figure 3 This is a comparison chart of the detection probabilities of the method according to the embodiment of the present invention and the single-band detection method. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention Figure 1 to Figure 3 , the technical solutions, structural features, objectives achieved and effects in the embodiments of the present invention are described in detail.

[0035] It should be noted that the drawings are in a very simplified form and use non-precise proportions. They are only used to conveniently and clearly assist in explaining the embodiments of the present invention, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention.

[0036] It should be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only the elements explicitly listed, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0037] The invention discloses a dual-band weak target detection method based on Hough transform, performs parameter domain changes on dual-frequency multi-frame data, utilizes distance resolution and speed resolution to perform grid division on the parameter domain transformation spectrum after Hough transform, calculates the intensity of each grid point after specific weight derivation, and compares the intensity of each grid with the threshold intensity of the grid to distinguish the target. The weak target detection method of the invention has high efficiency, and can still maintain stable detection performance when the external interference noise conditions change greatly, and has good robustness.

[0038] The technical solution of the present invention will be described below in conjunction with specific embodiments.

[0039] like Figure 1 As shown, a dual-band weak target detection method based on Hough transform in an embodiment of the present invention comprises the following steps:

[0040] S1. Select beams of two frequency bands of the radar and align the beams of the two frequency bands in space and time. Specifically, align the beams of the two frequency bands to the target area at the same time, and use the same timestamp as the starting time for scanning. The two frequency bands can be selected according to the actual situation and the specific radar.

[0041] S2, obtaining the echo data of the beams of the two frequency bands, and setting the initial detection thresholds respectively for initial target detection;

[0042] In this embodiment, the initial detection threshold is set by combining a fixed threshold with CFAR (constant false alarm rate) detection to perform initial detection. Specifically, the initial detection threshold in this embodiment is: in, Among them, α is the threshold coefficient, To estimate the interference power, x i is the power of the i-th detection unit, and N is the number of detection units. In actual situations, the larger the N, the better the effect, but at the same time the amount of calculation will also increase, so the size of N can be determined according to actual needs;

[0043] For the echo data of the two frequency band beams, the thresholds are calculated and set according to the above formulas, and the initial detection of the target is performed, and the detection units whose values ​​in the two sets of echo data are smaller than the corresponding initial detection thresholds are excluded respectively. This step S2 is a preliminary screening to preliminarily reduce the detection data and improve the detection efficiency.

[0044] S3, for the two groups of echo data after the preliminary detection in S2, respectively use the pre-installed information to perform wide constraint detection, and select the detection units that meet the motion feature constraints;

[0045] The pre-installed information may be a priori knowledge such as multi-target distance, speed, angle, energy and signal-to-noise ratio. In this embodiment, the target distance limit, speed limit and acceleration limit in two adjacent frames are selected as the target motion feature constraints, wherein the speed limit is the speed limit value of the target motion, that is, V min ≤V i ≤V max , where V i is the velocity of the target in the i-th frame, V min is the theoretical minimum speed of the target movement, V max is the theoretical maximum speed of the target motion, and the acceleration limit is the acceleration limit of the target motion, that is, |a i |≤a max , where a max is the acceleration limit of the target motion, a i is the acceleration of the target in the i-th frame, and the target distance between two adjacent frames is limited to ΔR min ≤ΔR i,i+1 ≤ΔR max , ΔR i,i+1 is the distance difference between the target in the i-th frame and the i+1-th frame, ΔR min is the minimum theoretical distance of the target's movement in two adjacent frames, ΔR max is the maximum theoretical distance of the target's movement in two adjacent frames, T is the time interval between two adjacent frames; the detection units that meet the motion feature constraints in the two sets of echo data are screened out, which can greatly reduce the detection data and improve the target detection efficiency;

[0046] S4: for the two groups of detection units screened out by S3, dual-frequency fusion detection is performed based on Hough transform, and the target point is determined in the parameter domain transform spectrum after Hough transform. The step S4 specifically includes the following steps:

[0047] S41. Perform parameter domain Hough transform on the two sets of echo data respectively, map the echo signal from the frequency-time domain to the distance-velocity domain according to the parameter domain transformation method, and then fuse the distance-velocity domain spectra of different frequency bands into the same coordinate system to generate a parameter domain transformation spectrum; wherein, the parameter domain transformation method is in the form of: ρ = μsinθ + tcosθ, wherein (μ, t) is the coordinate in the rectangular coordinate system, ρ is the normal distance from the origin to the straight line, and θ is the positive angle between the normal and the x-axis; Figure 2 , which is a schematic diagram of generating parameter domain transform spectrum based on two sets of echo data;

[0048] S42, for the parameter domain transform spectrum, grid division is performed according to the distance resolution and the velocity resolution, and the grid point intensity y is calculated. i Fill the grid;

[0049] Grid division is performed according to the distance resolution and speed resolution, specifically including: determining the distance resolution ΔR and the speed resolution ΔV, where B is the bandwidth of the radar signal, c is the speed of light, λ is the radar wavelength, f r is the pulse repetition frequency; the distance axis and the velocity axis are divided, and the number of grids on the distance axis is R max is the maximum detection distance of the radar, and the number of grids on the velocity axis is V max is the maximum detectable speed of the radar; generating a grid on the range axis and the speed axis based on the range resolution ΔR and the speed resolution ΔV;

[0050] The grid point intensity y i The calculation steps are as follows: take n frames from the radar scanning results of the two frequency band beams, and the grid point intensity y i The value is 0≤y i ≤10 (here 10 is the maximum number of detectable targets. In this embodiment, it is planned that a maximum of 10 targets can be detected), y i=α1n1+α2n2, where α1 is the specific weighted value of the first frequency band, n1 is the number of lines of the first frequency band that fall into the grid, α2 is the specific weighted value of the second frequency band, n2 is the number of lines of the second frequency band that fall into the grid, where R1 and R2 are the maximum detection distances of the first frequency band and the second frequency band under the detection system parameters, respectively, and are determined by the properties of the detection system itself. In this embodiment, n is 5, and in other embodiments, other values ​​may also be used.

[0051] S43, calculate the intensity threshold y of the grid r , and compare y i and r , so as to determine the target point, specifically: if y i <y r , it means there is no target, if y i ≥y r , it means there is a target; the intensity threshold y of the grid r Determined by the detection system itself.

[0052] S5, using Hough inverse transform to output the measurement values ​​of each dimension;

[0053] The distance and speed of the target point determined in step S4 are the distance and speed of the target. The target point is inversely transformed through the parameter domain formula to obtain the measurement values ​​of each dimension of the target.

[0054] By adopting the technology of the present invention, the detection efficiency of the target can be greatly improved. Figure 3 As shown, it is a probability comparison diagram of target detection using the method of the present invention (dual-frequency fusion) and single-frequency band interception and single-frequency band single frame. It can be seen that the probability of finding the target in weak target detection by the method of the present invention is significantly improved.

[0055] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A dual-band weak target detection method based on Hough transform, characterized in that: The following steps are involved: S1. Select the two frequency bands of the radar beams, align the two frequency bands beams in space and time, and scan the target area; S2, obtaining the echo data of the beams of the two frequency bands, and setting the initial detection thresholds respectively for initial target detection; S3, for the two groups of echo data after the preliminary detection in S2, respectively use the pre-installed information to perform wide constraint detection, and select the detection units that meet the motion feature constraints; S4, for the detection units selected by S3, dual-frequency fusion detection is performed based on Hough transform, and the target point is determined in the parameter domain transform spectrum after Hough transform; S5. For the target point determined in S4, Hough inverse transform is used to output the measurement values ​​of each dimension.

2. The dual-band weak target detection method based on Hough transform as claimed in claim 1, characterized in that: Step S1 specifically includes: aiming the beams of two frequency bands at the target area at the same time, and using the same timestamp as the start time for scanning.

3. The dual-band weak target detection method based on Hough transform as claimed in claim 1, characterized in that: In step S2, for the two sets of echo data, the initial detection threshold is set by combining the fixed threshold with the CFAR detection to perform initial detection, and the detection units in the two sets of echo data that are smaller than the corresponding initial detection threshold are excluded.

4. The dual-band weak target detection method based on Hough transform as claimed in claim 3, characterized in that: The initial detection threshold is in, Among them, α is the threshold coefficient, To estimate the interference power, x i is the power of the i-th detection unit, and N is the number of detection units.

5. The dual-band weak target detection method based on Hough transform as claimed in claim 1, characterized in that: In step S3, the target distance limit, speed limit and acceleration limit in two adjacent frames are selected as the motion feature constraints of the target.

6. The dual-band weak target detection method based on Hough transform as claimed in claim 5, characterized in that: The speed limit is the speed limit of the target movement, which is V min ≤V i ≤V max , where V i is the velocity of the target in the i-th frame, V min is the theoretical minimum speed of the target movement, V max is the theoretical maximum speed of the target motion; the acceleration limit is the acceleration limit value of the target motion, which is |a i |≤a max , where a max is the acceleration limit of the target motion, a i is the acceleration of the target in the i-th frame; the target distance between two adjacent frames is limited to ΔR min ≤ΔR i,i+1 ≤ΔR max , ΔR i,i+1 is the distance difference between the target in the i-th frame and the i+1-th frame, ΔR mim is the minimum theoretical distance of the target's movement in two adjacent frames, ΔR max is the maximum theoretical distance of the target's movement in two adjacent frames, T is the time interval between two adjacent frames. Separation.

7. The dual-band weak target detection method based on Hough transform as claimed in claim 1, characterized in that: Step S4 includes the following steps: S41, performing parameter domain Hough transform on the two groups of echo data respectively, mapping the echo signal from the frequency-time domain to the distance-velocity domain according to the parameter domain transform method, and then fusing the distance-velocity domain spectra of different frequency bands into the same coordinate system to generate a parameter domain transform spectrum; S42, for the parameter domain transform spectrum, grid division is performed according to the distance resolution and the velocity resolution, and the grid point intensity y is calculated. i Fill the grid; S43, calculate the intensity threshold y of the grid r , and compare y i and r , thereby determining the target point.

8. The dual-band weak target detection method based on Hough transform as claimed in claim 7, characterized in that: The grid point intensity y i The calculation steps are as follows: take n frames from the radar scanning results of the two frequency band beams, and the grid point intensity y i The value is 0≤y i ≤X,y i =α1n1+α2n2, where X is the maximum number of detectable targets, α1 is the specific weighted value of the first frequency band, n1 is the number of lines of the first frequency band that fall into the grid in n frames, α2 is the specific weighted value of the second frequency band, n2 is the number of lines of the second frequency band that fall into the grid in n frames, R1 and R2 are the maximum detection distances of the first and second frequency bands respectively under the detection system parameters.

9. The dual-band weak target detection method based on Hough transform as claimed in claim 7, characterized in that: In step S43, if y i <y r , it means there is no target, if y i ≥y r , it means there is a goal.

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