A radar high-voltage power line recognition method based on double-band features

Abstract

The application relates to the technical field of radar signal processing, and discloses a radar high-voltage power line identification method based on a double-waveband feature. The method adopts a multi-frequency band method, utilizes the Bragg feature difference of echoes of different wavebands, distinguishes the Bragg scattering echo feature from other target echo features of the ground, realizes Bragg feature distinction of the high-voltage line, finally detects the high-voltage line, greatly reduces false alarm generation, and realizes more accurate detection of the high-voltage line.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radar signal processing, and particularly relates to a radar high-voltage power line identification method based on double-band features. BACKGROUND

[0002] Helicopters are widely equipped and applied in the world. They play an important role in short-distance transportation, medical rescue, fire extinguishing and the like. However, the helicopters frequently collide with low-altitude obstacles, especially when the line of sight is not good, and the high-voltage line is the main problem threatening the flight safety of the helicopters, and the detection of the high-voltage line becomes an important means to ensure the safety of the helicopters.

[0003] The high-voltage line is very thin, and the pilot is affected by weather, background and light during flight, and it is difficult to be found by naked eyes, and becomes the most dangerous obstacle in low-altitude flight of the helicopter. The millimeter wave radar adopts millimeter wave band microwaves for anti-collision detection, and has all-weather and all-day anti-collision capability, and is the main equipment of the anti-collision sensor of the helicopter. The millimeter wave radar can detect the high-voltage line due to the Bragg reflection point formed by the characteristics of the high-voltage line strand. However, the ground is more and more densely populated with man-made buildings, and too many ground echoes make the reflection of the high-voltage line easily mixed with the echoes of the ground buildings, street lamps and railings, and the millimeter wave radar echoes are easily misassociated, resulting in too many false alarms of the high-voltage line detection, and affecting the real high-voltage line detection. Too many false alarms of the millimeter wave high-voltage line detection seriously affect the flight judgment of the pilot, and therefore it is necessary to reduce the false alarm and improve the detection accuracy under complex conditions.

[0004] The most direct and effective detection method is to find the characteristics of the high-voltage line different from the conventional ground echoes, and the characteristics of the high-voltage line echoes are simply introduced as follows:

[0005] The high-voltage line is wound by a plurality of metal aluminum wires, and a group of high-voltage lines is composed of two or more live wires and ground wires, and the structure is as shown in Figure 1 The structure of the medium and high-voltage line, due to the unique structure of the high-voltage line, when the radar wave irradiates the surface of the high-voltage line, strong scattering will be generated at several specific angles, and the scattering at the several angles is called Bragg scattering, and the Bragg scattering angle can be calculated by the following formula:

[0006] (1-1)

[0007] In the formula, is the wavelength, is the first scattering peak angle, The pitch cycle represents the pitch between adjacent strands; the scattering peak reaches the maximum at the incident angle of 0°, which is called the Bragg scattering main lobe, and other scattering peaks are called side lobes. According to Bragg scattering, the position of the strong echo of the high-voltage line is directly related to the beam irradiation angle and the radar frequency.

[0008] In addition to Bragg scattering, the scattering of the high-voltage line at other angles is very weak. Moreover, the high-voltage line Bragg scattering echo gradually weakens as the bias angle increases, greater than 15° or greater than 20°, the Bragg scattering is almost not obtained (as shown in the figure). Figure 2 For example, the Ka band and the W band are combined to perform dual-band high-voltage line identification. According to formula 1-1, the Ka band with a longer wavelength has a larger first Bragg point angle than the W band. The Bragg peaks of the W band and the Ka band have angle differences and intensity differences on the echo image, which makes it possible to distinguish and detect the high-voltage line by using dual-band.

[0009] Therefore, how to distinguish the Bragg scattering echo feature from other target echo on the ground to realize the Bragg feature distinction of the high-voltage line and solve the problems of weak high-voltage line signal detection, complex scene detection, and false alarm suppression becomes an urgent problem to be solved. SUMMARY

[0010] Therefore, the present application provides a radar high-voltage power line identification method based on dual-band features. The method uses a multi-band method to distinguish the Bragg scattering echo feature from other target echo on the ground, realizes the Bragg feature distinction of the high-voltage line, and finally detects the high-voltage line, greatly reduces the false alarm, and realizes more accurate detection of the high-voltage line.

[0011] A radar high-voltage power line identification method based on dual-band features, comprising the following steps:

[0012] Step 1: A dual-band radar is used to emit radar signals in the entire angle range, and the obtained echo data of the two frequencies containing Bragg scattering echoes are preprocessed to obtain preprocessed data.

[0013] Step 2: The intensity difference of the preprocessed data is compared to obtain intensity difference data.

[0014] Step 3: The threshold of the preprocessed data is set, and the intensity difference data corresponding to the preprocessed data higher than the threshold are found out.

[0015] Step 4: The intensity difference data threshold is set, and the Hough transform is performed on the intensity difference data greater than the corresponding threshold to obtain Hough transform data.

[0016] Step five, set the Hough transform data detection threshold, more than the detection threshold is determined to be the position data of high voltage line.

[0017] Further, the preprocessing of the echo data in step one includes the following steps:

[0018] The dual-band radar transmits M azimuth beams in the entire angle measurement range, and the distance is N sampling points. After pulse compression processing and absolute value calculation, the echo data of the two frequencies are respectively and , wherein the value of any position is , , m∈1~M, n∈1~N;

[0019] Two echo intensity calibration coefficients , wherein is the weight of the echo at different positions.

[0020] The two data echo intensities are calibrated by multiplying by times, and the preprocessing is realized.

[0021] Further, the method for obtaining the intensity difference data according to the preprocessed data in step two is:

[0022]

[0023] The intensity difference data after comparison of the echoes of the two frequencies.

[0024] Further, the method for determining the intensity difference data corresponding to the preprocessed data containing the threshold in step three is:

[0025] All positions in greater than and all positions in greater than are determined as points where the signal is obviously higher than the white noise, and the difference matrix is obtained.

[0026] , wherein is the value of any position, , and are the noise intensity suppression thresholds of the echoes of the two bands, respectively.

[0027] Further, the method for obtaining the Hough transform data in step four is:

[0028] First, an empty matrix , the sampling number is ; the B equally spaced samples of the dimension B angle ~ , the corresponding angle is , the corresponding number ;

[0029] Set the intensity difference data threshold , all > The point is adopted polar coordinate Hough transform ; The angle corresponding to the m position echo is , the sampling distance corresponding to n is

[0030] Iterate , The corresponding Hough transform result , ) in Find the distance closest to the angle The position point of , and increase the count value of the point In 1;

[0031] Get the final Hough transform matrix .

[0032] Further, the detection threshold of the count value in step five is set to , the value exceeding the detection threshold In It is considered to be a real high-voltage line, and those below the detection threshold are discarded as false alarms, and the corresponding distance angle high-voltage line is finally obtained.

[0033] Compared with the prior art, the beneficial effects of the present application are:

[0034] 1、The present application adopts a multi-band method, utilizes the Bragg characteristic difference of echoes of different wave bands, distinguishes the Bragg scattering echo characteristics from other target echoes on the ground, realizes the Bragg characteristic distinction of high-voltage lines, finally detects the high-voltage lines, greatly reduces the false alarm generation, and realizes more accurate detection of high-voltage lines.

[0035] 2、The present application is more beneficial to detecting high-voltage lines in a strong clutter background, reduces the false association of high-voltage lines, makes the high-voltage line detection more accurate, can be used for radar multi-band system design and detection algorithm design of low-altitude flight collision avoidance radars such as helicopters, fixed-wing aircrafts and unmanned aerial vehicles, and can effectively suppress the high-voltage line false alarm caused by clutter. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0037] Figure 1 Bragg scattering principle diagram for high-voltage lines;

[0038] Figure 2 Bragg scattering echo characteristic diagram for different wave bands;

[0039] Figure 3 Flowchart of a radar high-voltage power line identification method based on dual-wave band characteristics in Embodiment 1 or 2;

[0040] Figure 4 High-voltage line diagram displayed after setting a pretreatment data threshold in Embodiment 2;

[0041] Figure 5 High-voltage line diagram displayed after setting an intensity difference data threshold in Embodiment 2. DETAILED DESCRIPTION

[0042] The embodiments of the present application will be described in detail below with reference to the drawings.

[0043] The embodiments of the present application will be described in detail below with reference to the drawings.

[0044] Embodiment 1

[0045] Reference is made to Figure 3 A radar high-voltage power line identification method based on dual-wave band characteristics, comprising the following steps:

[0046] Step 1: A dual-wave band radar is used to emit radar signals in the entire angle measurement range, and the obtained two frequencies contain echo data of Bragg scattering echoes, and the echo data is pretreated to obtain pretreatment data;

[0047] Step 2: Compare the intensity differences of the preprocessed data to obtain intensity difference data;

[0048] Step 3: Set a threshold for the preprocessed data and identify the intensity difference data corresponding to preprocessed data that exceeds the threshold;

[0049] Step 4: Set a threshold for intensity difference data, and perform Hough transform on intensity difference data that exceeds the corresponding threshold to obtain Hough transform data;

[0050] Step 5: Set the Hough transform data detection threshold. Data exceeding the detection threshold is identified as high-voltage line location data.

[0051] In this embodiment, by utilizing the differences in Bragg characteristics of echoes from different wavebands, Bragg scattering echoes are distinguished from ground echoes based on the characteristics of Bragg scattering echoes. This allows for the differentiation of Bragg scattering echo characteristics from other target echoes on the ground, thereby enabling the differentiation of high-voltage lines based on their Bragg characteristics. Ultimately, this leads to the detection of high-voltage lines, greatly reducing false alarms and achieving more accurate detection of high-voltage lines.

[0052] Example 2

[0053] See Figures 3-5 To make the objectives, features, and advantages of this invention more apparent and understandable, this embodiment uses radar operating at 30 GHz (corresponding to echo angles of a certain high-voltage line deviating from the vertical point by 13.3° and -13.3°) and 80 GHz (corresponding to echo angles of a certain high-voltage line deviating from the vertical point by 5°, 10° and -5°, -10°) as examples to provide a detailed description of the method of this invention:

[0054] Step 1: Perform intensity calibration on the received signal at different distances.

[0055] A dual-band radar transmits M=61 azimuth beams across the entire angular measurement range, with N=1000 sampling points at a distance. The resulting echo data at the two frequencies, after pulse compression processing and absolute value calculation, are as follows: and The value at any position is , For m∈1~M, n∈1~N, the angle corresponding to the echo at position m is... The sampling distance corresponding to n is expressed as The echo intensity of these two data points is then calibrated. Calibration coefficient. ,in Weighting of echoes from different locations.

[0056] Will enlarge Double the strength to complete the strength calibration.

[0057] Step 2: Compare the differences between echoes of different frequencies.

[0058] Compare the echoes of two different frequencies using the following formula to obtain the comparison results. :

[0059]

[0060] Step 3: Search for points in the echo that are higher than the white noise.

[0061] Establish a difference matrix The value at any position is , = =2.8, which are the noise intensity suppression thresholds for the echoes of the two bands, respectively, for all Medium to large and all Medium to large The location is determined to be a point where the signal is significantly higher than the white noise. Find... The values ​​are as follows:

[0062]

[0063] Step 4: Analyze the results obtained in Step 3. Results (e.g.) Figure 4 Make a judgment if the ratio > =10, then perform a Hough transform. The Hough transform only applies to this layer. > The position is transformed as follows to obtain the Hough transformed image. (or expressed as a matrix) ).

[0064] In this embodiment, the image after Hough transform The specific process can be as follows:

[0065] First, create an empty matrix. A corresponds to A equal intervals between the minimum and maximum detection ranges of the radar, with the corresponding distance being... The sampling sequence number is ; Regarding dimension B ~ B equally spaced samples, corresponding to angles of Corresponding serial number ;

[0066] Set intensity difference data threshold All > The point of the Hough transform is taken in polar coordinates ; The angle corresponding to the m position echo, The sampling distance corresponding to n;

[0067] Traverse , The result of the Hough transform corresponding to (H (r, θ)) , ) in Find the angle The nearest Position point corresponding to the distance, and increase the count value of this point in by 1;

[0068] Get the final Hough transform matrix As shown in Figure 5 .

[0069] Step five: set the detection threshold to , the value in above the detection threshold is considered to be a real high-voltage line, and below the detection threshold is discarded as false alarm. Finally, the corresponding distance angle high-voltage line is obtained, achieving the purpose of suppressing false alarm of fuzzy signal.

[0070] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.​

Claims

1. A radar high-voltage power line recognition method based on dual-band features, characterized in that, The method comprises the following steps: Step one, using dual-band radar to transmit radar signals in the whole angle measurement range, obtaining two frequency containing Bragg scattering echo data, and pre-processing the echo data to obtain pre-processed data; Step two, comparing the intensity difference of the pre-processed data to obtain intensity difference data; Step three, setting a threshold for the pre-processed data, and finding out the intensity difference data corresponding to the pre-processed data higher than the threshold; Step four, setting an intensity difference data threshold, and performing Hough transform on the intensity difference data greater than the corresponding threshold to obtain Hough transform data; Step five, setting a Hough transform data detection threshold, and determining the position data of the high-voltage line when the Hough transform data exceeds the detection threshold.

2. The dual-band feature based radar high voltage power line identification method of claim 1, wherein, The pre-processing of the echo data in step one comprises the following steps: The dual-band radar transmits M azimuth beams in the whole angle measurement range, and the distance is N sampling points. After pulse compression processing and absolute value calculation, the obtained echo data of two frequencies are and wherein the value of any one position is , , m ∈ 1 ~ M, n ∈ 1 ~ N; Two echo intensity calibration coefficients wherein is a weighting of the echoes of different positions; Calibration of the two data echo intensities was performed to achieve preprocessing by amplifying amplification times.

3. The dual-band feature based radar high voltage power line identification method of claim 2, wherein, The method for obtaining the intensity difference data from the pre-processed data in step two is: is the difference in intensity of the compared echoes for the two frequencies.

4. The dual-band feature based radar high voltage power line identification method of claim 3, wherein, The determination method for the intensity difference data corresponding to the pre-processed data higher than the threshold in step three is: All greater than and all greater than The positions of wherein is an arbitrary position value, , are noise intensity suppression thresholds for the two waveband echoes, respectively.

5. The dual-band feature based radar high voltage power line identification method of claim 4, wherein, The method for obtaining the Hough transform data in step four is: Firstly, an empty matrix is established , A corresponds to the minimum distance of radar detection to the maximum detection distance A interval sampling, the corresponding distance is , the sampling number is ; the dimension B angle ~ B interval sampling, the corresponding angle is , the corresponding number is ; Setting intensity difference data threshold , all points are taken by polar Hough transform ; is the angle corresponding to the echo of m position, is the sampling distance corresponding to n;​ traversing , the result of a corresponding Hough transform , ) in finding the angle the closest location point and increasing the count value of this point in by 1; obtaining a final hough transformed matrix .

6. The dual-band feature based radar high voltage power line identification method of claim 5, wherein, The detection threshold of the count value in step five is set as The value exceeding the detection threshold in step five is considered as a real high-voltage line, and the value below the detection threshold is discarded as a false alarm. The value exceeding the detection threshold in step five is considered as a real high-voltage line, and the value below the detection threshold is discarded as a false alarm. The value exceeding the detection threshold in step five is considered as a real high-voltage line, and the value below the detection threshold is discarded as a false alarm.

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