A processing method for estimating wall penetration based on radar echo

Abstract

The present invention relates to a method for estimating wall penetration based on radar echo. After estimating the wall penetration, the processing method outputs the processing result for use in radar data processing, and adjusts the sensitivity of the radar in real time. The processing method includes accumulation, distance compensation, sorting, summation, ratio, and then estimates the wall penetration; wherein the accumulated radar echo signal is a frequency domain signal after sampling by the radar front-end AD chip and FFT processing by the FPGA chip. The processing method of the present invention has a simple algorithm and does not occupy too much system resources and time overhead; at the same time, it is simple and fast to implement, and does not require advance installation or collection; the processing result is concise, clear, accurate, and real-time, which can be used for real-time adjustment during radar data processing, eliminating the influence of wall differences on radar performance and accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of through-wall radar detection, and in particular to a processing method for estimating wall penetration based on radar echoes. Background Art

[0002] Through-the-wall radar transmits electromagnetic waves toward the target through the transmitting antenna. When the electromagnetic waves encounter obstacles (such as walls), reflection, refraction and scattering will occur. Some electromagnetic waves will penetrate the wall and continue to propagate. When encountering a target hidden behind the wall (such as a human body), they will be reflected again. The reflected electromagnetic waves are received by the receiving antenna and transmitted to the signal processing unit for analysis and processing. By analyzing the amplitude, phase, frequency and other parameters of the received signal, the location, distance, speed and other information of the hidden target can be determined. However, in actual use, the radar needs to penetrate walls of different materials to locate the target, and the dispersion and attenuation of walls of different materials are also different. The material, thickness, humidity, surface roughness and internal structure of the wall all affect the detection capability of the radar. Therefore, these factors need to be fully considered in practical applications to improve the accuracy and reliability of detection.

[0003] The following methods are usually used to deal with the impact of wall differences on through-wall radar detection: 1) Multi-band detection: Use radar waves of multiple different frequency bands for detection. Electromagnetic waves of different frequency bands have different propagation characteristics in walls. By comprehensively analyzing the detection results of multiple frequency bands, the impact of wall differences can be alleviated to a certain extent; 2) Signal processing technology: Use advanced signal processing algorithms such as filtering, denoising, and clutter suppression to reduce the clutter interference caused by wall reflection and scattering, and enhance the recognition and extraction of target echoes; 3) Modeling and compensation: Establish an electromagnetic propagation model for common wall types, and compensate and correct the radar detection results according to the material, thickness, humidity and other parameters of the wall to improve the detection accuracy; 4) On-site calibration: Before actual detection, conduct on-site calibration tests on specific walls to obtain relevant parameters of the wall, and adjust the radar's working parameters and signal processing methods accordingly. However, these methods are cumbersome and complicated to implement. In actual through-wall radars, target information needs to be obtained quickly and accurately when in use, so the above correction methods are not suitable for real usage scenarios. Summary of the invention

[0004] To this end, the technical problem to be solved by the present invention is to overcome the existing technology that measures walls of various materials and thicknesses, calculates their echo data, and repeatedly tests them, and finds that the undulations on the wall surface, the uneven distribution of wall materials, and the different placement of antennas will cause changes in wall echoes. Since the correlation between strong clutter signals such as wall echoes is much greater than the correlation between the wall and the target, the presence or absence of a target behind the wall has little effect on the strong clutter signal. Therefore, the strong clutter signal can be used to estimate the penetration of the wall. Therefore, the strong clutter signal can be used to estimate the penetration of the wall; thereby providing a simple, fast, and highly accurate processing method for estimating the penetration of the wall, and the processing result can be provided for use in radar data processing, and the sensitivity of the radar can be adjusted in real time to reduce the impact of wall differences on the radar detection precision and accuracy.

[0005] In order to solve the above technical problems, the present invention provides a processing method for estimating wall penetration based on radar echo. After estimating the wall penetration, the processing method outputs the processing result for use in radar data processing, and adjusts the sensitivity of the radar in real time. The processing method includes accumulation, distance compensation, sorting, summation, and ratio, and specifically includes the following steps:

[0006] Step S1: After the radar echo is sampled by the front-end AD and processed by FFT, the radar echo frequency domain signal is obtained;

[0007] Step S2: performing K group accumulation on the frequency domain signal;

[0008] Step S3: When K groups are accumulated, the accumulated frequency domain signals are subjected to distance compensation calculation;

[0009] Step S4: sorting the frequency domain signals after distance compensation calculation from small to large according to amplitude;

[0010] Step S5: summing up 20 data from the 46th to the 65th bits of the sorted signal;

[0011] Step S6: Calculate the ratio of the summed data to the reference value;

[0012] Step S7: Analyze the ratio value and send it to subsequent radar data processing;

[0013] Step S8: Repeat the above steps S2 to S7 in a loop until the radar system sends a stop command;

[0014] In step S7, a ratio analysis is performed, that is, a ratio greater than 1 indicates high penetration, and a larger value indicates stronger radar penetration capability; a ratio less than 1 indicates low penetration, and a smaller ratio indicates weaker radar penetration capability.

[0015] The compensation algorithm for distance calculation in step S3 is as follows:

[0016] y k (t) =x k (t)*(n*ΔR) 2

[0017] In the formula, x k (t) represents the amplitude after K times accumulation at the distance unit x, ΔR is the radar distance accuracy, n represents the number of points on the radar echo distance unit, y k (t) represents the value after the points on the distance unit are accumulated K times and then calculated after distance compensation.

[0018] In one embodiment of the present invention, the radar echo signal accumulated in step S1 is a frequency domain signal sampled by a radar front-end AD chip and processed by FFT on an FPGA chip.

[0019] In one embodiment of the present invention, the signal accumulation in the frequency domain in step S2 is coherent accumulation, and the accumulation algorithm is as follows:

[0020]

[0021] Where K represents the number of accumulated groups, The amplitude of the nth echo at distance unit x Represents the amplitude after K times accumulation at distance unit x.

[0022] In one embodiment of the present invention, the value of the cumulative number of groups K is 28, which is based on the verification radar of the present application scheme and is comprehensively selected through preliminary experiments and tests. It is actually related to factors such as the center frequency, bandwidth, and radar data processing rate of the radar.

[0023] In one embodiment of the present invention, the calculation formula of step S5 is as follows:

[0024]

[0025] Where y x (t) represents the value after the points on the x-th distance unit are accumulated K times and then calculated after distance compensation. Sum is the sum of the distance-compensated values ​​of 20 points from the 46th point to the 65th point.

[0026] In one embodiment of the present invention, the reference value in step S6 is based on a set of test data collected by the radar of this solution with 37 cm aerated bricks as the measured object according to steps S2 to S5.

[0027] The above technical solution of the present invention has the following advantages compared with the prior art:

[0028] The processing method described in the present invention has a simple algorithm for estimating wall penetrability based on radar echo, does not occupy too many system resources and time expenditure; at the same time, it is simple and fast to implement and does not require advance installation or collection; the processing result is concise, clear, accurate, and real-time, which can be used for real-time adjustment during radar data processing to eliminate the impact of wall differences on radar performance and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0030] Figure 1 It is a design block diagram of the method for estimating wall penetration based on radar echo of the present invention.

[0031] Figure 2 It is the accumulated waveform of various common wall radar frequency domain original echoes in the present invention.

[0032] Figure 3 It is the data waveform of the original echo accumulated from various common walls after distance compensation in the present invention.

[0033] Figure 4 It is the data waveform after various common wall distance compensation data in the present invention are sorted from small to large. DETAILED DESCRIPTION

[0034] like Figure 1 As shown, this embodiment provides a processing method for estimating wall penetration based on radar echo, by accumulating multiple groups of echo signals, and then performing distance compensation on the corresponding distance unit echo amplitude. After the compensated data is sorted, the value of the middle segment can characterize the wall penetration. Using this feature, the radar can select a certain wall as a standard wall and collect echo data. After the above processing, the collected and processed data is compared with the standard wall data, and then the penetration of the measured wall is analyzed. This quantified penetration result can be transmitted to the radar terminal for real-time display, characterizing the detection capability of the radar as a whole, and can also be provided to the radar data processing, differential processing of the target echo, or real-time adjustment of the target discrimination threshold, so as to weaken the influence of wall differences on target detection.

[0035] The processing method consists of the steps of accumulation, distance compensation, sorting, summation, ratio, etc. The specific steps are as follows:

[0036] Step S1: After the radar echo is sampled by the front-end AD and processed by FFT, the radar echo frequency domain signal is obtained;

[0037] Step S2: perform K groups of coherent accumulation on the frequency domain signal (the K value in this patent is 28);

[0038] Step S3: When K groups are accumulated, the accumulated frequency domain signals are subjected to distance compensation calculation;

[0039] Step S4: sorting the frequency domain signals after distance compensation calculation from small to large according to amplitude;

[0040] Step S5: summing up 20 data from the 46th to the 65th bits of the sorted signal;

[0041] Step S6: Calculate the ratio of the summed data to the reference value;

[0042] Step S7: Analyze the ratio value and send it to subsequent radar data processing;

[0043] Step S8: Repeat the above steps S2 to S7 in a loop until the system sends a stop command;

[0044] In step S7, a ratio analysis is performed, that is, a ratio greater than 1 indicates high penetration, and a larger value indicates stronger radar penetration capability; a ratio less than 1 indicates low penetration, and a smaller ratio indicates weaker radar penetration capability.

[0045] like Figure 2 As shown in the figure, the signal accumulation in the frequency domain is the coherent accumulation of 28 consecutive sets of frequency domain signals. The waveform changes of the accumulated data are basically the same, and the data peaks are concentrated in fixed (strong clutter) positions. The accumulation algorithm is as follows:

[0046]

[0047] Where K represents the number of accumulated groups, The amplitude of the nth echo at distance unit x Represents the amplitude after K times accumulation at distance unit x.

[0048] like Figure 3 As shown in the figure, after the distance compensation algorithm, the accumulated data waveform changes. The distance compensation algorithm is as follows:

[0049] y k (t) = x k (t) *(n*ΔR) 2

[0050] Where x k (t) represents the amplitude after K times accumulation at the distance unit x, ΔR is the radar distance accuracy, n represents the number of points on the radar echo distance unit, y k (t) represents the value after the points on the distance unit are accumulated K times and then calculated after distance compensation.

[0051] After the distance compensation algorithm, the data appears more chaotic.

[0052] like Figure 4 As shown, the data after distance compensation are sorted from small to large. The data differences of different walls can be clearly seen in the sorted middle segment data. The distribution of the middle segment data is consistent and the differences are obvious, which can characterize the penetrability of the wall.

[0053] As shown in Table 1, the data of the middle section (the 46th to 65th bits are selected in this patent) are summed, and the data of the 37cm aerated brick is used as a benchmark. The other wall data and the data are compared with the data. The ratio can quantify the penetrability of the wall. This value can be brought into the subsequent radar data processing so that the radar can correct the wall effect in real time. The summation calculation formula is as follows:

[0054]

[0055] Where y x (t) represents the value after the points on the x-th distance unit are accumulated K times and then calculated after distance compensation. Sum is the sum of the distance-compensated values ​​of 20 points from the 46th point to the 65th point.

[0056] In summary, after the above processing, the wall permeability can be accurately distinguished and its permeability can be directly quantified in digital form.

[0057] In order to verify the feasibility of this design method, with the help of the existing hardware platform, five common wall types (37cm red brick wall, 37cm aerated brick wall, 24cm red brick wall, 15cm concrete wall, 15cm reinforced concrete wall) and air environment were detected and the test data were collected for processing, comparison and analysis.

[0058] pass Figure 2 It can be seen that the data waveform distribution of radar echoes after passing through various walls is basically the same, and the penetrability of the wall cannot be directly obtained. However, after the processing method described in this patent, Figure 4 It can be clearly seen that the differences between the walls are as follows: air environment > 15cm concrete wall > 15cm steel-concrete wall > 24cm red brick wall > 37cm aerated brick wall > 37cm red brick wall. The calculated results are basically consistent with the measured wall penetrability.

[0059] As shown in the following table, the penetration ratios calculated for six types of test scenarios are listed. It can also be seen from the table that, based on the 37cm aerated brick, the quantified air environment penetration ratio is 7.12; the 15cm concrete wall penetration ratio is 3.03; the 15cm steel-concrete wall penetration ratio is 2.27; the 24cm red brick wall penetration ratio is 1.16; and the 37cm red brick wall penetration ratio is 0.17. It can be concluded that a ratio greater than 1 indicates high penetration, and the larger the ratio, the stronger the radar penetration ability. A ratio less than 1 indicates low penetration, and the smaller the ratio, the weaker the radar penetration ability.

[0060] Location 37cm plus brickwork 37cm red brick 15cm concrete 24cm red brick 15cm steel-concrete Empty Environment 46 124282530 25721644.21 417823213.8 144080868.1 302675843.3 985762449.0 47 126533141.3 25744736.48 421194962.6 146925000 306037192.4 1030602796.0 48 131401052.1 25784491.22 422002250.4 154656250 314785136.3 1052582993.0 49 135270693.6 26617898.25 434957724 155583774.7 336883610.9 1070235439.4 50 139182481.3 26748201.6 447076659.4 161239535.6 350015923.1 1092968428.1 51 140231250 27046432.33 460275000 164496339.5 351816285.9 1099924116.3 52 150990599.8 27935878.91 465000000 176849039.8 358739578.1 1112914167.5 53 153246744.2 27967684.57 469940850 178170874.8 361991531.6 1122754633.6 54 153750000 28094909.45 496194678.1 179417896.7 362186012.5 1204529524.9 55 167209019.1 29151092.25 497950705.4 182512088.3 366468233.3 1217850390.0 56 170000000 29883848.58 508223776.5 186200000 381922382.8 1228638067.1 57 179889855.1 29993592.13 533850515.4 198189184.6 385061453 1235760602.1 58 186406380 30152420.16 536206656 207668671.9 392097349.2 1258247798.4 59 189897845.3 30230543.02 544577826.9 221012552.3 411951299.9 1261059600.0 60 191456671.9 30311464.13 549480261.2 221620174.7 421436367.2 1281868601.1 61 193903137.5 31280004.44 568961976.6 225518073.8 422179955.8 1305343566.4 62 193955131.5 31304593.94 582031250 245867737.9 435008917 1308024128.5 63 203649508 31339631.35 583993476.6 249320031.6 451789018.1 1338188867.4 64 203966024.6 31366864.13 610911296 251925437.9 453178567.1 1395441696.0 65 220848604.5 31981733.09 616186407.6 265383931.5 473272550 1420060471.3 Sum 3356070670 578657664.2 10166839486 3916637464 7639497207 24022758336.1 ratio 1 0.17242118 3.029387783 1.167030688 2.276321913 7.158001335

[0061] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A processing method for estimating wall penetration based on radar echo, wherein after estimating the wall penetration, the processing method outputs the processing result for use in radar data processing and adjusts the sensitivity of the radar in real time, characterized in that: The processing method includes accumulation, distance compensation, sorting, summation, and ratio, which specifically includes the following steps: Step S1: After the radar echo is sampled by the front-end AD and processed by FFT, the radar echo frequency domain signal is obtained; Step S2: performing K group accumulation on the frequency domain signal; Step S3: When K groups are accumulated, the accumulated frequency domain signals are subjected to distance compensation calculation; Step S4: sorting the frequency domain signals after distance compensation calculation from small to large according to amplitude; Step S5: summing up 20 data from the 46th to the 65th bits of the sorted signal; Step S6: Calculate the ratio of the summed data to the reference value; Step S7: Analyze the ratio value and send it to subsequent radar data processing; Step S8: Repeat the above steps S2 to S7 in a loop until the radar system sends a stop command; In step S7, the ratio analysis is performed, that is, a ratio greater than 1 indicates high penetration, and a larger value indicates stronger radar penetration capability, a ratio less than 1 indicates low penetration, and a smaller ratio indicates weaker radar penetration capability; The compensation algorithm for distance calculation in step S3 is as follows: y k (t) =x k (t)*(n*ΔR) 2 In the formula, x k (t) represents the amplitude after K times accumulation at the distance unit x, ΔR is the radar distance accuracy, n represents the number of points on the radar echo distance unit, y k (t) represents the value after the points on the distance unit are accumulated K times and then calculated after distance compensation.

2. The processing method according to claim 1, characterized in that: The radar echo signal accumulated in step S1 is a frequency domain signal sampled by the radar front-end AD chip and processed by the FPGA chip through FFT.

3. The processing method according to claim 1, characterized in that: The signal accumulation in the frequency domain in step S2 is coherent accumulation, and the accumulation algorithm is as follows: Where K represents the number of accumulated groups, The amplitude of the nth echo at distance unit x Represents the amplitude after K times accumulation at distance unit x.

4. The processing method according to claim 3, characterized in that: The value of the cumulative number of groups K is 28.

5. The processing method according to claim 1, characterized in that: The calculation formula of step S5 is as follows: Where y x (t) represents the value after the points on the x-th distance unit are accumulated K times and then calculated after distance compensation. Sum is the sum of the distance-compensated values ​​of 20 points from the 46th point to the 65th point.

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