Ultra-wideband ground penetrating radar transmitting link design method based on pseudo-random coding

Abstract

The invention belongs to the technical field of communication, and particularly relates to an ultra-wideband ground penetrating radar transmitting link design method based on pseudo-random coding. The pseudo-random code generation module is connected with the serial-to-parallel conversion module, the serial-to-parallel conversion module is connected with the double data transmission rate module, and the double data transmission rate module is connected with the signal emission module; the pseudo-random code generation module is used for generating high-speed pseudo-random codes; the serial-to-parallel conversion module is used for integrating four paths of parallel data into one path of serial data and outputting the serial data; the double data transmission rate module is used for converting a signal transmitted only at a rising edge into a form that the rising edge and a falling edge are sampled and transmitted; and the signal transmitting module is used for transmitting the high-speed pseudo-random codes sampled at the rising edge and the falling edge. The detection resolution of the ground penetrating radar and the signal-to-noise ratio of a transmitted signal are improved.

Description

Technical Field

[0001] This invention belongs to the technical field of communication, specifically designing a method for ultra-wideband ground-penetrating radar transmission link based on pseudo-random coding. Background Technology

[0002] Ground-penetrating radar (GPR) utilizes the reflection and scattering phenomena of high-frequency electromagnetic waves at discontinuities in the medium's properties to image and locate shallow surfaces or deep strata, thereby enabling the detection of underground targets. With the rapid development of electronics and computer technology, GPR, due to its advantages of speed, high resolution, and non-destructive testing, is widely used in various fields.

[0003] Currently, the most mature application is the impulsive pulse ground-penetrating radar, which detects objects by emitting high-frequency pulse signals at a specific frequency. With technological advancements, higher demands are being placed on the detection depth and resolution of ground-penetrating radar. Greater detection depth requires higher transmission power, while higher resolution necessitates extremely narrow pulse widths. Increasing peak power often saturates the receiver, resulting in a large detection blind zone, and increasing pulse width leads to a decrease in resolution. Therefore, traditional ground-penetrating radar struggles to simultaneously achieve both deep detection depth and high resolution.

[0004] In ground penetrating radar systems, traditional impulsive pulse ground penetrating radar transmitters are mostly built using analog circuits, making system debugging quite complicated. During transmission and reception, they are highly susceptible to radio frequency signal interference, which can lead to problems such as unstable output waveforms or trailing phenomena.

[0005] Furthermore, ground-penetrating radar is a bistatic detection radar with a very close distance between the transmitting and receiving antennas. The largest interference signal in the receiver originates from the direct wave reflected directly from the ground after the transmitter. Simultaneously, due to attenuation by the underground lossy medium, the strength of the echo signal containing target information is much lower than the strength of noise signals such as the direct wave signal. Therefore, the transmitted signal must have low sidelobe characteristics to avoid target signal loss.

[0006] Ground penetrating radar (GPR) transmission links based on pseudo-random coding are relatively rare both domestically and internationally. Pseudo-random coding is mostly used in the field of communications, and it has a large time-bandwidth product, allowing signal energy to be evenly distributed within a large time window. At the same time, pseudo-random coding has noise-like characteristics, good autocorrelation characteristics, and strong anti-interference capabilities. It can also improve the signal-to-noise ratio through pulse compression, enabling low-power and high-resolution designs for GPR. Summary of the Invention

[0007] This invention provides a design method for an ultra-wideband ground-penetrating radar (GPR) transmission link based on pseudo-random coding, which improves the detection resolution and signal-to-noise ratio of the transmitted signal.

[0008] This invention is achieved through the following technical solution:

[0009] A design method for an ultra-wideband ground-penetrating radar (UWPR) transmission link based on pseudo-random coding is disclosed. The transmission link includes a pseudo-random coding generation module, a serial-to-parallel conversion module, a double data transmission rate module, and a signal transmission module. The pseudo-random coding generation module is connected to the serial-to-parallel conversion module, the serial-to-parallel conversion module is connected to the double data transmission rate module, and the double data transmission rate module is connected to the signal transmission module.

[0010] The pseudo-random code generation module is used to generate high-speed pseudo-random codes;

[0011] The serial-to-parallel conversion module is used to integrate four parallel data streams into one serial data stream for output.

[0012] The double data transmission rate module is used to convert signals that are transmitted only on the rising edge to a form in which both the rising and falling edges are sampled and transmitted.

[0013] The signal transmission module is used to transmit high-speed pseudo-random codes that are sampled on both the rising and falling edges.

[0014] Furthermore, the pseudo-random code generation module consists of multiple XOR gates and registers, with the initial state of each register position being (a0, a1, ..., a...). n-2 ,a n-1 After one shift linear feedback, the input at the left end of the shift register is...

[0015]

[0016] Among them, c i An integer representing 0 or 1.

[0017] Furthermore, the output a of the pseudo-random coding generation module n This refers to the generated pseudo-random signal, which, according to a reasonable setting of c... i The value of is determined when the output pseudo-random sequence a is... k When the period is at its maximum, it is the desired m-sequence;

[0018] Based on the fundamental distribution characteristics of m-sequence pseudo-random codes, the autocorrelation function of m-sequence pseudo-random codes can be obtained under the following conditions:

[0019]

[0020] Where k is the single-cycle code length.

[0021] Furthermore, let the transmitted signal be x(t) and the echo signal reflected back from the target be y(t). Then the impulse response function h(t) between the transmitted signal and the echo signal contains the target position information; therefore, the cross-correlation function between the transmitted signal and the echo signal is:

[0022]

[0023] Then there is

[0024]

[0025]

[0026] Among them, R xx (t) is the autocorrelation function of the transmitted signal, R xy (τ) is the cross-correlation function between the transmitted signal and the echo signal, T is the pulse width, x is the transmitted signal, and t is the time.

[0027] As can be seen from equation (5), when the autocorrelation function of the transmitted signal approaches the impulse function, the cross-correlation function of the transmitted signal and the echo signal is equivalent to the system impulse response function h(t).

[0028] Furthermore, the pseudo-random code generation module is synthesized through a digital synthesis method. Specifically, the pseudo-random code generation module generates a set m-sequence output value in real time and then saves it to the random access memory in the FPGA as the control word of the DAC chip.

[0029] Furthermore, in order to generate pseudo-random encoded signals with frequencies up to gigahertz, it is necessary to combine the parallel-to-serial conversion primitives, double data transmission rate primitives, and DAC chips with multiple data interfaces inside the FPGA, and generate and transmit high-speed pseudo-random encoded signals through the low-speed, stable clock inside the FPGA.

[0030] Furthermore, the transmission of the high-speed pseudo-random coded signal specifically refers to f s This is the internal operating clock of the FPGA, which is connected to the FPGA's internal DAC sampling data memory. d For the operating clock of the DDR interface, f dac It is the operating clock of the external high-speed DAC, generated by a specific clock chip, where f dac =8f d =16f s This enables the FPGA to generate high-speed pseudo-random codes using a low-speed clock.

[0031] Furthermore, the FPGA reads the m-sequence pseudo-random code stored in RAM and sends it to the 4:1 parallel-to-serial conversion module. After the parallel-to-serial conversion primitive, the four parallel data channels are integrated into one serial data output. DDR is a dual-edge sampling mode. By calling the ODDR primitive, the signal that was originally transmitted only on the rising edge is converted to a form in which both the rising and falling edges are sampled and transmitted, which improves the efficiency of sampling and transmitting data. Finally, the control word is sent to the DAC chip. The analog signal generated by the DAC chip can generate a smooth ultra-wideband signal with pseudo-random encoding by passing through the low-pass filter in the signal band.

[0032] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the method described above.

[0033] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0034] The beneficial effects of this invention are:

[0035] This invention improves the detection resolution of ground penetrating radar: pseudo-random coding can increase the transmitted signal energy and improve the detection resolution of ground penetrating radar by increasing the code length while keeping the bandwidth constant.

[0036] This invention reduces the power consumption of the ground penetrating radar transmitter: the ground penetrating radar transmission signal based on pseudo-random coding has a large time-bandwidth product, which can evenly distribute the transmission signal energy over a large time range, reduce the instantaneous transmission power, reduce the power consumption of the ground penetrating radar transmitter, and at the same time avoid damage to the signal transmitter and receiver caused by excessive peak power.

[0037] This invention improves the signal-to-noise ratio (SNR) of ground-penetrating radar (GPR) transmitted signals: the pseudo-random coding has good autocorrelation characteristics and strong anti-interference ability, thereby improving the SNR and facilitating subsequent echo signal data processing. At the same time, the aperiodic autocorrelation function of the m-sequence pseudo-random coding is close to the impulse function, and has a high peak-to-sidelobe ratio, which is beneficial for GPR echo signal acquisition and processing.

[0038] The invention features a highly stable transmission link: Compared with traditional pulse ground-penetrating radar, this invention uses more digital circuits, making debugging simpler. At the same time, it uses the FPGA's internal parallel-to-serial conversion module and data dual-edge transmission module to achieve high-speed pseudo-random encoded data transmission using a stable low-speed clock, ensuring system timing stability. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the framework of the present invention.

[0040] Figure 2 This is a schematic diagram of the pseudo-random code generation module of the present invention.

[0041] Figure 3 This is a pseudo-random coding modulation waveform diagram of the present invention, wherein (a) is a pseudo-random sequence 1100010, (b) is a pulse signal with a pulse width of T, and (c) is an output signal modulated by pseudo-random sequence signals generated by different feedback coefficients.

[0042] Figure 4 This is a schematic diagram of the specific structure of the high-speed pseudo-random coded signal transmission link of the present invention. Detailed Implementation

[0043] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.

[0044] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0045] It should also be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0046] The following is in conjunction with the appendix to this application specification. Figure 1-3 The technical solutions in the embodiments of this application are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0047] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0048] Example 1

[0049] This embodiment discloses a design method for an ultra-wideband ground-penetrating radar transmission link based on pseudo-random coding. The transmission link includes a pseudo-random coding generation module, a serial-to-parallel conversion module, a double data transmission rate module, and a signal transmission module. The pseudo-random coding generation module is connected to the serial-to-parallel conversion module, the serial-to-parallel conversion module is connected to the double data transmission rate module, and the double data transmission rate module is connected to the signal transmission module.

[0050] The pseudo-random code generation module is a programmable gate array (FPGA); the pseudo-random code generation module is used to generate high-speed pseudo-random codes.

[0051] The serial-to-parallel conversion module is used to integrate four parallel data streams into one serial data stream for output.

[0052] The double data transmission rate module ODDR is used to convert signals that are transmitted only on the rising edge to a form in which both the rising and falling edges are sampled and transmitted.

[0053] The signal transmission module is used to transmit high-speed pseudo-random codes that are sampled on both the rising and falling edges.

[0054] Pseudo-random coding is widely used in communication systems to extend communication technology. It generates a sequence with properties similar to random noise but is completely deterministic through corresponding algorithms, hence the name pseudo-random sequence. Among them, the m-sequence is a common pseudo-random sequence in pseudo-random coding; it is the longest linear feedback shift register sequence, and its aperiodic autocorrelation function approximates the impulse function, making it widely applicable in radar detection.

[0055] Furthermore, the pseudo-random code generation module consists of multiple XOR gates and registers, with the initial state of each register position being (a0, a1, ..., a...). n-2 ,a n-1 After one shift linear feedback, the input at the left end of the shift register is...

[0056]

[0057] Among them, c i An integer representing 0 or 1.

[0058] Furthermore, the output a of the pseudo-random coding generation module n This refers to the generated pseudo-random signal, which, according to a reasonable setting of c... i The value of is determined when the output pseudo-random sequence a is... k When the period is at its maximum, it is the desired m-sequence;

[0059] Based on the fundamental distribution characteristics of m-sequence pseudo-random codes, the autocorrelation function of m-sequence pseudo-random codes can be obtained under the following conditions:

[0060]

[0061] Where k is the single-cycle code length.

[0062] Furthermore, let the transmitted signal be x(t) and the echo signal reflected back from the target be y(t). Then the impulse response function h(t) between the transmitted signal and the echo signal contains the target position information; therefore, the cross-correlation function between the transmitted signal and the echo signal is:

[0063]

[0064] Then there is

[0065]

[0066]

[0067] Among them, R xx (t) is the autocorrelation function of the transmitted signal, R xy (τ) is the cross-correlation function between the transmitted signal and the echo signal, where T is the pulse width, x is the transmitted signal, and t is the time.

[0068] As can be seen from equation (5), when the autocorrelation function of the transmitted signal approaches the impulse function, the cross-correlation function of the transmitted signal and the echo signal is equivalent to the system impulse response function h(t).

[0069] Therefore, ground-penetrating radar signals based on pseudo-random sequence coding have stronger detection capabilities than traditional pulse ground-penetrating radar. Pseudo-random sequence coded pulse signals maintain the resolution of traditional pulse signals while enabling the transmission of long pulse signals at low power, thereby increasing the energy of ground-penetrating radar detection signals and improving detection performance.

[0070] Furthermore, pseudo-random coding has a large time-bandwidth product, which can increase the energy of signal transmission by increasing the code length. At the same time, the signal energy can be evenly distributed over a large time range, avoiding the damage to the transmitter and receiver caused by the excessive peak power of traditional pulse ground-penetrating radar.

[0071] Furthermore, to facilitate the transmission of pseudo-random signals, a binary-modulated pseudo-random coded signal is typically used as the transmitted signal. To obtain the binary-modulated signal, two methods can be employed. The first method utilizes modulation and demodulation techniques to perform a mixing operation on the signal to be transmitted. For example, a pseudo-random sequence like 1100010... Figure 3 As shown in (a). Figure 3(b) is a pulse signal with a pulse width of T, and the output signal is modulated by pseudo-random sequence signals generated by different feedback coefficients, as shown in the figure. Figure 3 As shown in (c). Since the bandwidth of an ultra-wideband signal is comparable to its center frequency, modulation is difficult. This invention utilizes the programmability of an FPGA to synthesize pseudo-random codes using a digital synthesis method, and then uses a high-speed DAC to realize signal generation and transmission functions. The pseudo-random code generation module synthesizes the codes using a digital synthesis method. Specifically, the pseudo-random code generation module generates a set m-sequence output value in real time and saves it to the random access memory (RAM) in the FPGA as the control word for the DAC chip.

[0072] Furthermore, since the internal clock frequency of an FPGA chip can generally only operate below 500MHz, excessively high clock frequencies are prone to timing violations. Therefore, in order to generate pseudo-random encoded signals with frequencies up to gigahertz, it is necessary to combine the FPGA's internal parallel-to-serial conversion primitive (OSERDES2), double data transfer rate (ODDR) primitive, and a DAC chip with multiple data interfaces to generate and transmit high-speed pseudo-random encoded signals through the FPGA's internal low-speed and stable clock.

[0073] Furthermore, the transmission of the high-speed pseudo-random coded signal specifically includes, for example... Figure 4 As shown, f s This is the internal operating clock of the FPGA, which is connected to the FPGA's internal DAC sampling data memory (RAM1~RAM16). d For the operating clock of the DDR interface, f dac It is the operating clock of the external high-speed DAC, generated by a specific clock chip, where f dac =8f d =16f s This enables the FPGA to generate high-speed pseudo-random codes using a low-speed clock.

[0074] Furthermore, the FPGA reads the m-sequence pseudo-random code stored in RAM and sends it to the 4:1 parallel-to-serial conversion module. After the parallel-to-serial conversion primitive, the four parallel data channels are integrated into one serial data output. DDR is a dual-edge sampling mode. By calling the ODDR primitive, the signal that was originally transmitted only on the rising edge is converted to a form in which both the rising and falling edges are sampled and transmitted, which improves the efficiency of sampling and transmitting data. Finally, the control word is sent to the DAC chip. The analog signal generated by the DAC chip can generate a smooth ultra-wideband signal with pseudo-random encoding by passing through the low-pass filter in the signal band.

[0075] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the method described above.

[0076] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0077] Example 2

[0078] This invention provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor. The memory stores software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory and processor are connected via a bus. Specifically, the processor implements any of the steps in Embodiment 1 by running the computer program stored in the memory.

[0079] It should be understood that, in the embodiments of the present invention, the processor may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0080] Memory may include read-only memory, flash memory, and random access memory, and provides instructions and data to the processor. Some or all of the memory may also include non-volatile random access memory.

[0081] This invention improves the detection resolution of ground-penetrating radar (GPR): Through theoretical derivation, GPR based on pseudo-random coded pulse signals shares the same measurement principle as traditional pulse GPR. Pseudo-random coding can increase the transmitted signal energy and thus improve the detection resolution of GPR by increasing the code length while maintaining the bandwidth. It also reduces the power consumption of the GPR transmitter: The transmitted signal of GPR based on pseudo-random coding has a large time-bandwidth product, which can evenly distribute the transmitted signal energy over a large time range, reducing instantaneous transmitted power and lowering the power consumption of the GPR transmitter. Simultaneously, it avoids damage to the signal transmitter and receiver caused by excessive peak power. Furthermore, it improves the signal-to-noise ratio (SNR) of the GPR transmitted signal: Pseudo-random coding has good autocorrelation characteristics and strong anti-interference ability, thereby improving the SNR and facilitating subsequent echo signal data processing. At the same time, the aperiodic autocorrelation function of m-sequence pseudo-random coding is close to the impulse function, exhibiting a high peak-to-sidelobe ratio, which is beneficial for GPR echo signal acquisition and processing. Highly stable transmission link: Compared with traditional pulse ground-penetrating radar, this invention uses more digital circuits, which makes debugging simpler. At the same time, it uses the FPGA's internal parallel-to-serial conversion module and data dual-edge transmission module to achieve high-speed pseudo-random coded data transmission using a stable low-speed clock, ensuring the system's timing stability.

[0082] It should be understood that if the integrated modules / units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0083] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0084] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the above device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this invention. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0085] It should be noted that the methods and detailed examples provided in the above embodiments can be incorporated into the apparatus and devices provided in the embodiments, and can be referred to each other, without further elaboration.

[0086] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0087] In the embodiments provided by this invention, it should be understood that the disclosed apparatus / terminal devices and methods can be implemented in other ways. For example, the apparatus / device embodiments described above are merely illustrative. For instance, the division of modules or units described above is merely a logical functional division, and in actual implementation, it can be divided in other ways. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0088] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A design method for an ultra-wideband ground-penetrating radar transmission link based on pseudo-random coding, characterized in that, The transmission link includes a pseudo-random code generation module, a serial-to-parallel conversion module, a double data transmission rate module, and a signal transmission module; the pseudo-random code generation module is connected to the serial-to-parallel conversion module, the serial-to-parallel conversion module is connected to the double data transmission rate module, and the double data transmission rate module is connected to the signal transmission module. The pseudo-random code generation module is used to generate high-speed pseudo-random codes; The serial-to-parallel conversion module is used to integrate four parallel data streams into one serial data stream for output. The double data transmission rate module is used to convert signals that are transmitted only on the rising edge to a form in which both the rising and falling edges are sampled and transmitted. The signal transmission module is used to transmit high-speed pseudo-random codes that are sampled on both the rising and falling edges.

2. The ultra-wideband ground-penetrating radar transmission link design method according to claim 1, characterized in that, The pseudo-random code generation module consists of multiple XOR gates and registers, with the initial state of each register position being (a0, a1, ..., a...). n-2 ,a n-1 After one shift linear feedback, the input at the left end of the shift register is... Among them, c i An integer representing 0 or 1.

3. The ultra-wideband ground-penetrating radar transmission link design method according to claim 2, characterized in that, The output a of the pseudo-random encoding generation module n This refers to the generated pseudo-random signal, which, according to a reasonable setting of c... i The value of is determined when the output pseudo-random sequence a is... k When the period is at its maximum, it is the desired m-sequence; Based on the fundamental distribution characteristics of m-sequence pseudo-random codes, the autocorrelation function of m-sequence pseudo-random codes can be obtained under the following conditions: Where k is the single-cycle code length.

4. The ultra-wideband ground-penetrating radar transmission link design method according to claim 3, characterized in that, Let the transmitted signal be x(t), and the echo signal reflected back from the target be y(t). Then the impulse response function h(t) between the transmitted signal and the echo signal contains the target position information; the cross-correlation function between the transmitted signal and the echo signal is: Then there is Among them, R xx (t) is the autocorrelation function of the transmitted signal, R xy (τ) is the cross-correlation function between the transmitted signal and the echo signal, T is the pulse width, x is the transmitted signal, and t is the time. As can be seen from equation (5), when the autocorrelation function of the transmitted signal approaches the impulse function, the cross-correlation function of the transmitted signal and the echo signal is equivalent to the system impulse response function h(t).

5. The ultra-wideband ground-penetrating radar transmission link design method according to claim 1, characterized in that, The pseudo-random code generation module is synthesized through a digital synthesis method. Specifically, the pseudo-random code generation module generates a set m-sequence output value in real time and then saves it to the random access memory in the FPGA as the control word of the DAC chip.

6. The ultra-wideband ground-penetrating radar transmission link design method according to claim 5, characterized in that, To generate pseudo-random encoded signals with frequencies up to gigahertz, it is necessary to combine the parallel-to-serial conversion primitives, double data transmission rate primitives, and DAC chips with multiple data interfaces inside the FPGA. High-speed pseudo-random encoded signals are generated and transmitted through the low-speed, stable clock inside the FPGA.

7. The ultra-wideband ground-penetrating radar transmission link design method according to claim 6, characterized in that, The transmission of the high-speed pseudo-random encoded signal specifically refers to f s This is the internal operating clock of the FPGA, which is connected to the FPGA's internal DAC sampling data memory. d For the operating clock of the DDR interface, f dac It is the operating clock of the external high-speed DAC, generated by a specific clock chip, where f dac =8f d =16f s This enables the FPGA to generate high-speed pseudo-random codes using a low-speed clock.

8. The ultra-wideband ground-penetrating radar transmission link design method according to claim 6, characterized in that, The FPGA reads the m-sequence pseudo-random code stored in RAM and sends it to the 4:1 parallel-to-serial conversion module. The parallel-to-serial conversion primitive integrates the four parallel data channels into one serial data output. DDR is a dual-edge sampling mode. By calling the ODDR primitive, the signal that is transmitted only on the rising edge is converted into a form that is sampled and transmitted on both the rising and falling edges, which improves the efficiency of sampling and transmitting data. Finally, the control word is sent to the DAC chip. The analog signal generated by the DAC chip can generate a smooth, pseudo-randomly encoded ultra-wideband signal by passing through a low-pass filter in the signal band.

9. A computer device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements the method as described in any one of claims 2-8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method described in any one of claims 2-8.

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