A multi-channel chaos ground penetrating radar device for urban road disease detection

Abstract

The application belongs to the technical field of ground penetrating radar detection, and particularly relates to a multi-channel chaotic ground penetrating radar device for city road disease detection, which solves the technical problems of poor anti-interference ability of the existing multi-channel pulse ground penetrating radar and the problem that the multi-channels cannot work in parallel, wherein the signal generation unit comprises a pulse signal generation module and a chaotic pulse signal generation module; the transmitting and receiving unit comprises N transmitting and receiving subunits, each of which comprises a local oscillator signal generator, a three-way power divider, a first / second / third frequency mixer, a first / second power amplifier, a first / second transmitting antenna, a receiving antenna, a low-noise amplifier and a signal acquisition subunit; the signal matching unit comprises N signal matching subunits, each of which comprises a pulse detector and a pulse interval matching module; and the clock control unit is connected to the pulse signal generation module, the chaotic pulse signal generation module, the signal matching subunit and the transmitting and receiving subunit respectively.

Description

Technical Field

[0001] This invention relates to the field of ground-penetrating radar detection technology, and in particular to a multi-channel chaotic ground-penetrating radar device for detecting urban road defects. Background Technology

[0002] With the rapid development of urbanization and the continuous development of urban underground space resources, urban road collapse accidents occur frequently. Numerous road quality surveys have revealed a strong correlation between road collapses and underlying hidden defects. Ground penetrating radar (GPR), a non-destructive and rapid detection technology that uses electromagnetic wave reflection to determine the distribution of underground media, has become the preferred method for road defect detection. In recent years, to meet the requirements of rapid road detection without disrupting normal traffic, a series of vehicle-mounted GPR systems have been successfully developed. These vehicle-mounted GPR systems employ multi-channel or antenna array designs, allowing a single vehicle to simultaneously cover the entire lane horizontally, generating a large amount of data in a single scan and achieving high detection speed.

[0003] However, existing technologies have the following problems: Most existing multi-channel ground-penetrating radars (GPRs) use a pulse system, which has limited anti-interference capabilities. These are mainly reflected in the following aspects: 1. They are susceptible to electromagnetic interference from the surrounding environment. Due to the diverse functions and complex composition of urban roads, GPR echo signals are affected by numerous above-ground and underground interference sources, such as pipelines, cables, optical fibers, and other structures within the road, as well as overhead cables and signal transmitters, resulting in a low signal-to-noise ratio and causing significant difficulties in target detection and identification. 2. Multi-channel GPR is equivalent to multiple single-channel GPRs operating simultaneously. Each channel not only receives its own echo signal but may also receive transmitted signals from other channels, leading to misjudgments. This mutual interference between channels severely affects the detection performance of multi-channel GPR. To avoid crosstalk between channels, most existing technologies employ time-division multiplexing (CN202211245313.4, CN201611098515.5), allowing only one channel to operate at any given time. However, when multi-channel ground-penetrating radars operate on high-speed moving platforms such as vehicle-mounted or airborne systems, this can lead to significant measurement errors. Therefore, it is necessary to invent a ground-penetrating radar device with strong anti-interference capabilities and multi-channel parallel operation for urban road defect detection, in order to solve the aforementioned problems existing in current ground-penetrating radar systems. Summary of the Invention

[0004] To overcome the technical shortcomings of existing multi-channel pulse ground-penetrating radars, such as poor anti-interference capability and the inability of multiple channels to work in parallel, this invention provides a multi-channel chaotic ground-penetrating radar device for detecting urban road defects.

[0005] This invention provides a multi-channel chaotic ground-penetrating radar device for detecting urban road defects, comprising a signal generation unit, a transmission and reception unit, a signal matching unit, a signal processing unit, a clock control unit, and a display unit;

[0006] The signal generation unit includes a pulse signal generation module for generating N-channel periodic pulse signals and a chaotic pulse signal generation module for generating N-channel chaotic pulse signals.

[0007] The transmit / receive unit comprises N transmit / receive subunits. Each transmit / receive subunit includes a local oscillator signal generator, a three-way power divider, a first mixer, a second mixer, a third mixer, a first power amplifier, a second power amplifier, a first transmit antenna, a second transmit antenna, a receive antenna, a low-noise amplifier, and a signal acquisition subunit. The local oscillator signal generator generates three local oscillator signals through the three-way power divider. These three local oscillator signals are respectively connected to the first, second, and third mixers. The output of the first mixer is connected to the input of the first transmit antenna through the first power amplifier, and the output of the second mixer is connected to the input of the second transmit antenna through the second power amplifier. The output of the receive antenna is connected to the input of the third mixer through the low-noise amplifier. N periodic pulse signals are respectively connected to the first mixers of the N transmit / receive subunits, and N chaotic pulse signals are respectively connected to the second mixers of the N transmit / receive subunits. The first and second transmit antennas are used to transmit electromagnetic waves to the ground, and the receive antennas are used to receive echo signals. The output of the third mixer is used for signal acquisition by the signal acquisition subunit.

[0008] The signal matching unit comprises N signal matching subunits. Each subunit includes a pulse detector and a pulse interval matching module. The output of the pulse detector is connected to the input of the pulse interval matching module. N periodic pulse signals are connected to the pulse detectors and pulse interval matching modules of the N signal matching subunits, respectively. N chaotic pulse signals are also connected to the pulse detectors and pulse interval matching modules of the N signal matching subunits, respectively. The outputs of the N signal acquisition subunits are connected to the pulse detectors of the N signal matching subunits. The pulse detectors are equipped with amplitude and width thresholds. When the number of sampling points of the input signal is greater than the width threshold and the amplitude of the acquired signal is greater than the amplitude threshold, the input signal is considered to be a pulse echo signal. The pulse detector then inputs the pulse echo signal to the pulse interval matching module. The pulse interval matching module receives the periodic pulse signals. The system receives periodic and chaotic pulse signals and calculates the time interval between them. The pulse interval matching module also receives pulse echo signals detected by the pulse detector. If the time interval between two consecutive pulse echo signals matches the time interval between the periodic and chaotic pulse signals, the signal matching is considered successful. The signal matching subunit inputs the two successfully matched pulse echo signals to the signal processing unit for processing. The signal processing unit calculates the transmission and echo times of the periodic pulse signal to obtain a first delay time, and then calculates the transmission and echo times of the chaotic pulse signal to obtain a second delay time. The signal processing unit calculates the average delay time based on the first and second delay times to obtain the final time delay, and then calculates the target distance based on the time delay. The signal processing unit sends the target distance to the display unit in real time for display.

[0009] The clock control unit is connected to the pulse signal generation module, the chaotic pulse signal generation module, N signal matching subunits, and N transmit / receive subunits. The clock control unit is connected to the pulse signal generation module and the chaotic pulse signal generation module to provide a clock signal and ensure that both modules transmit signals simultaneously. The clock control unit is also connected to the N transmit / receive subunits to ensure that the signal acquisition subunits within these subunits sample simultaneously. Finally, the clock control unit is connected to the N signal matching subunits to provide a clock signal to each pulse detector and to ensure that all N signal matching subunits operate simultaneously.

[0010] Preferably, the pulse signal generation module includes a first pulse signal generator and a first N-channel power divider. The first pulse signal generator generates periodic pulse signals and generates N periodic pulse signals through the first N-channel power divider. The chaotic pulse signal generation module includes a chaotic mapping module, a counter, a comparator, a second pulse signal generator, a second N-channel power divider, and N electrical delay lines. The chaotic mapping module generates random numbers in the range [0,1]. The counter starts counting from zero. The output terminals of the chaotic mapping module and the counter are both connected to the input terminals of the comparator. The output terminal of the comparator is connected to the input terminal of the second pulse signal generator. The second pulse signal generator and the second N-channel power divider... The system is connected to a power divider, which generates N chaotic pulse signals. These N chaotic pulse signals are then output after passing through N electrical delay lines. The output of the chaotic mapping module is compared with the output of the counter. When the output of the counter is greater than the output of the chaotic mapping module, a second pulse signal generator is triggered to generate a new chaotic pulse signal. This new chaotic pulse signal is fed back in a closed loop to the inputs of the counter and the chaotic mapping module. The rising edge of the pulse signal triggers a reset of the counter to zero, and the output of the chaotic mapping module is updated to enter the next state. The chaotic mapping module uses a hybrid method of improved Logistic mapping and Type I 3rd-order Chebychev polynomial to generate a composite chaotic mapping.

[0011] The formula for calculating the improved Logistic mapping is as follows:

[0012] ;

[0013] The type I third-order Chebychev polynomial is:

[0014] The formula for calculating the composite chaotic mapping is: .

[0015] The interval between each periodic pulse signal and each chaotic pulse signal varies randomly within each pulse repetition period. The periodic pulse signal is up-converted by the first mixer and amplified by the first power amplifier before being transmitted to the ground via the first transmitting antenna. The chaotic pulse signal is up-converted by the second mixer and amplified by the second power amplifier before being transmitted to the ground via the second transmitting antenna. The signals transmitted to the ground by the first and second transmitting antennas are reflected when they encounter interfaces between different underground media, forming echo signals. These echo signals are down-converted by the receiving antenna, low-noise amplifier, and mixer before entering the signal acquisition subunit for acquisition. After parallel sampling of N channels, the data is input into N signal matching subunits for pulse detection and pulse interval matching. The N signal matching subunits process the signals in parallel. If a match is successful, the pulse echo signal enters the signal processing unit for processing, and finally, it is displayed in real time on the display unit. The signal matching subunits eliminate signal interference from other channels and electromagnetic interference from the environment, allowing each channel to operate simultaneously without time-division multiplexing. The clock control unit generates a reference clock to control the clocks of the signal generation unit, signal acquisition unit, and signal matching unit. The signal generation unit, signal matching unit, signal processing unit, and clock control unit are all implemented on the FPGA. In the chaotic pulse signal generation module, because the cross-correlation between the delayed and undelayed chaotic pulse signals is small, the generated N chaotic pulse signals are orthogonal to each other. The trigger clocks of the first and second pulse signal generators are synchronized, and the interval between the periodic pulse signal and the chaotic pulse signal varies randomly within each pulse repetition period. The N transmit and receive subunits can change the center frequency of the transmitted signal by adjusting the local oscillator frequency of the local oscillator signal generator.

[0016] Preferably, the pulse repetition periods of the first pulse signal generator and the second pulse signal generator are the same, and the maximum delay time of the electrical delay line is less than the pulse repetition period; within the pulse repetition period, the interval between the periodic pulse signal and the chaotic pulse signal of the first pulse signal generator and the second pulse signal generator varies randomly.

[0017] Compared with the prior art, the technical solution provided by this invention has the following technical effects: The ground-penetrating radar device of this invention transmits a pair of periodic pulse signals and chaotic pulse signals with random intervals. The receiving end uses a pulse interval matching method to determine whether the echo signal comes from the pulse signal pair. This device combines the characteristics of traditional pulse radar and chaotic radar, possessing both the long detection range of pulse radar and the strong anti-interference capability of chaotic radar. It can ensure the detection depth of ground-penetrating radar and its resistance to external electromagnetic interference and interference from different channels, enabling rapid and accurate road defect detection in complex urban environments. The multiple channels of this device can be flexibly set to work frequency bands, further reducing interference between channels. On the other hand, through the effective combination of high, medium, and low frequency bands, it can balance detection depth and detection accuracy, providing richer and more accurate information on underground defects. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a multi-channel chaotic ground-penetrating radar device for detecting urban road defects, as described in a certain embodiment of the present invention.

[0021] In the diagram: 1. Local oscillator signal generator; 2. Three-way power divider; 3. First mixer; 4. Second mixer; 5. Third mixer; 6. First power amplifier; 7. Second power amplifier; 8. First transmitting antenna; 9. Second transmitting antenna; 10. Receiving antenna; 11. Low-noise amplifier; 12. Signal acquisition subunit; 13. Pulse detector; 14. Pulse interval matching module; 15. Signal processing unit; 16. Display unit; 17. Clock control unit; 18. First pulse signal generator; 19. First N-way power divider; 20. Chaotic mapping module; 21. Counter; 22. Comparator; 23. Second pulse signal generator; 24. Second N-way power divider. Detailed Implementation

[0022] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0023] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0025] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0026] In one embodiment, such as Figure 1 As shown, a multi-channel chaotic ground-penetrating radar device for detecting urban road defects is disclosed, including a signal generation unit, a transmission and reception unit, a signal matching unit, a signal processing unit 15, a clock control unit 17, and a display unit 16.

[0027] The signal generation unit includes a pulse signal generation module for generating N-channel periodic pulse signals and a chaotic pulse signal generation module for generating N-channel chaotic pulse signals.

[0028] The transmit / receive unit comprises N transmit / receive subunits. Each transmit / receive subunit includes a local oscillator signal generator 1, a three-way power divider 2, a first mixer 3, a second mixer 4, a third mixer 5, a first power amplifier 6, a second power amplifier 7, a first transmit antenna 8, a second transmit antenna 9, a receive antenna 10, a low-noise amplifier 11, and a signal acquisition subunit 12. The local oscillator signal generator 1 generates three local oscillator signals through the three-way power divider 2. These three local oscillator signals are respectively connected to the first mixer 3, the second mixer 4, and the third mixer 5. The output of the first mixer 3 is connected to the first transmit antenna 9 through the first power amplifier 6. The input terminal of the transmitting antenna 8 and the output terminal of the second mixer 4 are connected to the input terminal of the second transmitting antenna 9 through the second power amplifier 7; the output terminal of the receiving antenna 10 is connected to the input terminal of the third mixer 5 through the low-noise amplifier 11; N periodic pulse signals are respectively connected to the first mixer 3 of the N transmitting and receiving subunits, and N chaotic pulse signals are respectively connected to the second mixer 4 of the N transmitting and receiving subunits. The first transmitting antenna 8 and the second transmitting antenna 9 are used to transmit electromagnetic waves to the ground, and the receiving antenna 10 is used to receive echo signals; the output terminal of the third mixer 5 is used for signal acquisition through the signal acquisition subunit 12.

[0029] The signal matching unit includes N signal matching subunits. Each signal matching subunit includes a pulse detector 13 and a pulse interval matching module 14. The output of the pulse detector 13 is connected to the input of the pulse interval matching module 14. N periodic pulse signals are respectively connected to the pulse detectors 13 and pulse interval matching modules 14 of the N signal matching subunits. N chaotic pulse signals are also respectively connected to the pulse detectors 13 and pulse interval matching modules 14 of the N signal matching subunits. The outputs of the N signal acquisition subunits 12 are connected to the pulse detectors 13 of the N signal matching subunits. The pulse detector 13 is set with an amplitude threshold and a width threshold. When the number of sampling points of the input signal is greater than the width threshold and the amplitude of the acquired signal is greater than the amplitude threshold, the input signal is considered to be a pulse echo signal. Then, the pulse detector 13 inputs the pulse echo signal to the pulse interval matching module 14. The pulse interval matching module 14... The system receives periodic pulse signals and chaotic pulse signals, and calculates the time interval between them. The pulse interval matching module 14 also receives pulse echo signals detected by the pulse detector 13. If the time interval between two consecutive pulse echo signals is the same as the time interval between the periodic and chaotic pulse signals, the signal matching is considered successful. The signal matching subunit inputs the two successfully matched pulse echo signals to the signal processing unit 15 for processing. The signal processing unit 15 calculates the transmission time and echo time of the periodic pulse signal to obtain a first delay time, and then calculates the transmission time and echo time of the chaotic pulse signal to obtain a second delay time. The signal processing unit 15 calculates the average delay time based on the first and second delay times to obtain the final time delay, and then calculates the target distance based on the time delay. The signal processing unit 15 sends the target distance to the display unit 16 in real time for display.

[0030] The clock control unit 17 is connected to the pulse signal generation module, the chaotic pulse signal generation module, N signal matching subunits, and N transmit / receive subunits. The clock control unit 17 is connected to the pulse signal generation module and the chaotic pulse signal generation module to provide a clock and to ensure that the pulse signal generation module and the chaotic pulse signal generation module transmit signals simultaneously. The clock control unit 17 is connected to the N transmit / receive subunits to ensure that the signal acquisition subunits 12 in the N transmit / receive subunits perform simultaneous sampling. The clock control unit 17 is connected to the N signal matching subunits to provide a clock for each pulse detector 13 and to ensure that the N signal matching subunits work simultaneously.

[0031] Preferably, the pulse signal generation module includes a first pulse signal generator 18 and a first N-channel power divider 19. The first pulse signal generator 18 generates periodic pulse signals and generates N periodic pulse signals through the first N-channel power divider 19. The chaotic pulse signal generation module includes a chaotic mapping module 20, a counter 21, a comparator 22, a second pulse signal generator 23, a second N-channel power divider 24, and N electrical delay lines. The chaotic mapping module 20 generates random numbers in the range [0,1]. The counter 21 counts from zero. The output terminals of the chaotic mapping module 20 and the counter 21 are both connected to the input terminal of the comparator 22. The output terminal of the comparator 22 is connected to the second pulse signal generator 23. At the input terminal of module 3, the second pulse signal generator 23 is connected to the second N-channel power divider 24, which generates N chaotic pulse signals. These N chaotic pulse signals are then output after passing through N electrical delay lines. The output of the chaotic mapping module 20 is compared with the output of the counter 21 via a comparator 22. When the output of the counter 21 is greater than the output of the chaotic mapping module 20, the second pulse signal generator 23 is triggered to generate a new chaotic pulse signal. This new chaotic pulse signal is then fed back in a closed loop to the input terminals of the counter 21 and the chaotic mapping module 20. The rising edge triggers a reset of the counter 21 to zero, and updates the output of the chaotic mapping module 20 to enter the next state. The chaotic mapping module 20 employs a composite chaotic mapping. In a specific embodiment, the chaotic mapping module 20 uses a hybrid of a modified Logistic mapping and a Type I 3rd-order Chebychev polynomial to generate a composite chaotic mapping.

[0032] The improved Logistic mapping calculation formula is as follows:

[0033] ;

[0034] The type I third-order Chebychev polynomial is:

[0035] The formula for the composite chaotic mapping is: .

[0036] The interval between each periodic pulse signal and each chaotic pulse signal varies randomly within each pulse repetition period. The periodic pulse signal is up-converted by the first mixer 3, amplified by the first power amplifier 6, and then transmitted to the ground via the first transmitting antenna 8. The chaotic pulse signal is up-converted by the second mixer 4, amplified by the second power amplifier 7, and then transmitted to the ground via the second transmitting antenna 9. When the signals transmitted to the ground by the first transmitting antenna 8 and the second transmitting antenna 9 encounter different underground media interfaces, they are reflected to form echo signals. These echo signals are down-converted by the receiving antenna 10, the low-noise amplifier 11, and the mixer, and then enter the signal acquisition subunit 12 for acquisition. After parallel sampling of N channels, the data is input into N signal matching subunits for pulse detection and pulse interval matching. The N signal matching subunits process the data in parallel. If a match is successful, the pulse echo signal enters the signal processing unit 15 for processing, and finally, it is displayed in real time on the display unit. Through the signal matching subunits, signal interference from other channels and electromagnetic interference from the environment are eliminated, allowing each channel to work simultaneously without time-division multiplexing. The clock control unit 17 generates a reference clock to control the clocks of the signal generation unit, signal acquisition unit, and signal matching unit. The signal generation unit, signal matching unit, signal processing unit 15, and clock control unit 17 are all implemented on an FPGA. In the chaotic pulse signal generation module, because the cross-correlation between the delayed and undelayed chaotic pulse signals is small, the generated N chaotic pulse signals are orthogonal to each other. The trigger clocks of the first pulse signal generator 18 and the second pulse signal generator 23 are synchronized. Within each pulse repetition period, the interval between the periodic pulse signal and the chaotic pulse signal varies randomly. The N transmit / receive subunits can change the center frequency of the transmitted signal by adjusting the local oscillator frequency of the local oscillator signal generator 1.

[0037] Based on the above embodiments, in a preferred embodiment, the pulse repetition periods of the first pulse signal generator 18 and the second pulse signal generator 23 are the same, and the maximum delay time of the electrical delay line is less than the pulse repetition period; within the pulse repetition period, the interval between the periodic pulse signal and the chaotic pulse signal of the first pulse signal generator 18 and the second pulse signal generator 23 changes randomly.

[0038] Based on the above embodiments, in a preferred embodiment, the first transmitting antenna 8, the second transmitting antenna 9, and the receiving antenna 10 are shielded air-coupled planar antennas, and the center frequencies of the first transmitting antenna 8, the second transmitting antenna 9, and the receiving antenna 10 are consistent with the center frequencies of the periodic pulse signal, the chaotic pulse signal, and the local oscillator frequency of the local oscillator signal generator 1.

[0039] Based on the above embodiments, in a preferred embodiment, the shielded air-coupled planar antenna is a planar butterfly antenna, a planar Vivaldi antenna, or a planar helical antenna.

[0040] Based on the above embodiments, in a preferred embodiment, the local oscillator frequency of the local oscillator signal generator 1 is 160MHz, 270MHz, 400MHz, 600MHz or 900MHz.

[0041] Based on the above embodiments, in a preferred embodiment, the total length of the first transmitting antenna 8, the second transmitting antenna 9, and the receiving antenna 10 in the N transmitting and receiving subunits is less than or equal to 2m. All antenna arrays of the N transmitting and receiving subunits essentially cover the entire road surface without obstructing vehicles in adjacent lanes.

[0042] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A multi-channel chaotic ground penetrating radar device for urban road disease detection, characterized in that, It includes a signal generation unit, a transmission and reception unit, a signal matching unit, a signal processing unit (15), a clock control unit (17), and a display unit (16). The signal generation unit includes a pulse signal generation module for generating N-channel periodic pulse signals and a chaotic pulse signal generation module for generating N-channel chaotic pulse signals. The transmit / receive unit includes N transmit / receive subunits. Each transmit / receive subunit includes a local oscillator signal generator (1), a three-way power divider (2), a first mixer (3), a second mixer (4), a third mixer (5), a first power amplifier (6), a second power amplifier (7), a first transmit antenna (8), a second transmit antenna (9), a receive antenna (10), a low-noise amplifier (11), and a signal acquisition subunit (12). The local oscillator signal generator (1) generates three local oscillator signals through the three-way power divider (2). The three local oscillator signals are connected to the first mixer (3), the second mixer (4), and the third mixer (5), respectively. The output of the first mixer (3) is connected to the first power amplifier (6). The output of the second mixer (4) is connected to the input of the first transmitting antenna (8) via the second power amplifier (7); the output of the receiving antenna (10) is connected to the input of the third mixer (5) via the low-noise amplifier (11); N periodic pulse signals are connected to the first mixer (3) of the N transmitting and receiving subunits respectively, and N chaotic pulse signals are connected to the second mixer (4) of the N transmitting and receiving subunits respectively. The first transmitting antenna (8) and the second transmitting antenna (9) are used to transmit electromagnetic waves to the ground, and the receiving antenna (10) is used to receive echo signals; the output of the third mixer (5) is used to acquire signals through the signal acquisition subunit (12). The signal matching unit includes N signal matching subunits. Each signal matching subunit includes a pulse detector (13) and a pulse interval matching module (14). The output of the pulse detector (13) is connected to the input of the pulse interval matching module (14). N periodic pulse signals are connected to the pulse detectors (13) and pulse interval matching modules (14) of the N signal matching subunits, respectively. N chaotic pulse signals are connected to the pulse detectors (13) and pulse interval matching modules (14) of the N signal matching subunits, respectively. The output of the N signal acquisition subunits (12) is connected to the pulse detectors (13) of the N signal matching subunits. The pulse detector (13) is set with an amplitude threshold and a width threshold. When the number of sampling points of the input signal is greater than the width threshold and the amplitude of the acquired signal is greater than the amplitude threshold, the input signal is considered to be a pulse echo signal. Then, the pulse detector (13) inputs the pulse echo signal to the pulse interval matching module (14). The matching module (14) receives periodic pulse signals and chaotic pulse signals, and calculates the time interval between the periodic pulse signals and chaotic pulse signals. The pulse interval matching module (14) also receives pulse echo signals detected by the pulse detector (13). When the time interval between the two consecutive pulse echo signals is the same as the time interval between the periodic pulse signals and chaotic pulse signals, the signal matching is considered successful. The signal matching subunit inputs the two consecutive pulse echo signals that have been successfully matched to the signal processing unit (15) for processing. The signal processing unit (15) calculates the transmission time and echo time of the periodic pulse signal to obtain the first delay time, and then calculates the transmission time and echo time of the chaotic pulse signal to obtain the second delay time. The signal processing unit (15) calculates the average delay time based on the first delay time and the second delay time to obtain the final time delay, and then calculates the target distance based on the time delay. The signal processing unit (15) sends the target distance to the display unit (16) in real time for display. The clock control unit (17) is connected to the pulse signal generation module, the chaotic pulse signal generation module, N signal matching sub-units and N transmission and reception sub-units respectively. The clock control unit (17) is connected to the pulse signal generation module and the chaotic pulse signal generation module. On the one hand, it is used to provide the clock, and on the other hand, it is used to ensure that the pulse signal generation module and the chaotic pulse signal generation module transmit signals at the same time. The clock control unit (17) is connected to the N transmission and reception sub-units to ensure that the signal acquisition sub-units (12) in the N transmission and reception sub-units achieve simultaneous sampling. The clock control unit (17) is connected to the N signal matching sub-units to provide the clock for each pulse detector (13) and to ensure that the N signal matching sub-units work at the same time.

2. The multi-channel chaotic ground-penetrating radar device for detecting urban road defects according to claim 1, characterized in that, The pulse signal generation module includes a first pulse signal generator (18) and a first N-channel power divider (19). The first pulse signal generator (18) is used to generate periodic pulse signals and generate N periodic pulse signals through the first N-channel power divider (19). The chaotic pulse signal generation module includes a chaotic mapping module (20), a counter (21), a comparator (22), a second pulse signal generator (23), a second N-channel power divider (24), and N electrical delay lines. The chaotic mapping module (20) is used to generate [0 Random numbers within the range of ,1] are counted by the counter (21) starting from zero. The output of the chaotic mapping module (20) and the output of the counter (21) are both connected to the input of the comparator (22). The output of the comparator (22) is connected to the input of the second pulse signal generator (23). The second pulse signal generator (23) is connected to the second N-way power divider (24). The second N-way power divider (24) generates N chaotic pulse signals. The N chaotic pulse signals are output after passing through N electrical delay lines respectively. The output of the chaotic mapping module (20) is compared with the output of the counter (21) by the input comparator (22). When the output of the counter (21) is greater than the output of the chaotic mapping module (20), the second pulse signal generator (23) is triggered to generate a new chaotic pulse signal. The new chaotic pulse signal is fed back to the input terminals of the counter (21) and the chaotic mapping module (20) in a closed loop. The rising edge triggers the reset of the counter (21) to zero and updates the output of the chaotic mapping module (20) to enter the next state. The chaotic mapping module (20) uses a hybrid of improved Logistic mapping and type I third-order Chebychev polynomial to generate a composite chaotic mapping. The formula for calculating the improved Logistic mapping is as follows: ； The type I third-order Chebychev polynomial is: The formula for calculating the composite chaotic mapping is: .

3. A multi-channel chaotic ground-penetrating radar device for detecting urban road defects according to claim 2, characterized in that, The pulse repetition periods of the first pulse signal generator (18) and the second pulse signal generator (23) are the same, and the maximum delay time of the electrical delay line is less than the pulse repetition period. During the pulse repetition period, the interval between the periodic pulse signal and the chaotic pulse signal of the first pulse signal generator (18) and the second pulse signal generator (23) changes randomly.

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