Broadband phased array ground penetrating radar transmitter and method of controlling the same

Abstract

The present disclosure provides a broadband phased array ground penetrating radar transmitter and a control method thereof, and relates to the technical field of phased array radar detection, which comprises a control module, a time difference measurement unit based on TDC, a pulse shaping unit based on programmable microstrip line, a DDS module, a driving module and a Marx pulse circuit; the control module is used for parameter analysis and signal acquisition, and reads the waveforms and delay parameters stored in the waveform memory and sends them to the DDS module to generate trigger signals of each channel; the time difference measurement unit based on TDC measures the inherent trigger time difference between channels and feeds back to the control module for parameter correction; the driving module receives the trigger signal and triggers the Marx pulse circuit to generate a Gaussian pulse with extremely low time jitter; the pulse shaping unit based on programmable microstrip line is used to shape the Gaussian pulse into a single-period pulse, and the present disclosure realizes high time precision control and high peak power output of the transmitter, and is suitable for high-resolution phased array ground penetrating radar systems.

Description

Technical Field

[0001] This disclosure relates to the field of phased array radar detection technology, specifically to a broadband phased array ground penetrating radar transmitter and its control method. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] Ground-penetrating radar (GPR) is a non-destructive testing technology that uses the principle of high-frequency electromagnetic wave reflection to detect the distribution of underground media. It is widely used in transportation infrastructure, building construction quality inspection, and other fields, serving as an important means of detecting internal defects, cavities, cracks, and water content in engineering structures. Phased-array ground-penetrating radar is a new type of radar that introduces phased-array technology into the field of ground-penetrating radar. It achieves flexible beam scanning, focusing, and waveform synthesis by independently and precisely electronically controlling the amplitude and phase of the transmitted and received signals of each element of the array antenna. Compared to traditional single-channel pulse radar, three-dimensional array radar, and stepped-frequency ground-penetrating radar, phased-array ground-penetrating radar has significant advantages such as controllable beam pointing, high energy gain, and fast scanning speed, effectively solving key problems of conventional ground-penetrating radar such as insufficient underground detection depth, low operational efficiency, and low imaging signal-to-noise ratio.

[0004] The transmitter is the core unit of phased array radar for achieving beamforming and energy coverage. Currently, phased array radar transmitters used in air defense early warning, satellite communication, and meteorological detection typically prioritize high average power, high repetition frequency, and long operating range, often employing narrowband continuous wave or long pulse modulation schemes. However, ground-penetrating radar (GPR) operates through highly attenuating lossy media such as soil, rock, or concrete, where electromagnetic wave propagation attenuates exponentially. Conventional phased array transmitters struggle to provide high peak power excitation within extremely short timeframes, failing to meet the specific penetration requirements of GPR in deep-penetrating detection, thus limiting the application of phased array technology in underground engineering exploration.

[0005] While traditional ground-penetrating radar (GPR) pulses possess advantages such as high peak power, narrow pulse width, and good longitudinal resolution, their direct application in electronic scanning or multi-channel focusing within phased-array GPR still presents the following limitations:

[0006] (1) Firstly, since phased array ground-penetrating radar relies on the spatial coherent superposition of electromagnetic waves of different frequency components, when the phase shifter is used to beamform the broadband pulse directly, the beam pointing of different frequency components in the broadband signal will deviate, the synthesized waveform will undergo severe envelope broadening and waveform distortion in space, which will lead to inaccurate scanning direction control and energy focusing divergence, ultimately resulting in blurred imaging and loss of details.

[0007] (2) Secondly, traditional pulse triggering links inevitably suffer from nanosecond-level time jitter, and the fixed triggering error between channels is amplified as the number of array channels increases. Therefore, traditional ground-penetrating radar triggering links cannot achieve the stable phase relationship required for high-precision beamforming, resulting in the inability to achieve effective in-phase interference when multi-channel signals are superimposed in space, causing the power combining efficiency of the array to decline sharply;

[0008] (3) In practical engineering applications, different detection scenarios such as urban underground pipe network investigation, road cavity detection, and tunnel lining structure analysis have different requirements for detection depth and resolution. Existing transmitters are usually designed for fixed working depths, making it difficult to flexibly reconstruct the spectral characteristics of the transmitted waveform under the same transmission architecture, and unable to adaptively meet the contradictory requirements of "shallow high-resolution fine imaging" and "deep and deep penetration detection". Summary of the Invention

[0009] To address the aforementioned issues, this disclosure proposes a broadband phased array ground-penetrating radar transmitter and its control method. The transmitter utilizes an FPGA-integrated TDC to measure the trigger time difference of each channel in real time. A programmable microstrip pulse shaping network is employed, and a discrete, selectable pulse waveform library is formed through various diode branch combinations. This enables multi-channel transmission of instantaneous high-peak-power pulse signals, high-precision time delay control between channels, directional focusing and cyclic scanning of the ground-penetrating radar electromagnetic beam, and adapts to the comprehensive detection requirements of different detection depths and imaging resolutions.

[0010] According to some embodiments, the present disclosure adopts the following technical solutions:

[0011] A broadband phased array ground-penetrating radar transmitter includes a control module, a time difference measurement unit based on TDC, a pulse shaping unit based on programmable microstrip lines, a DDS module, a drive module, and a Marx pulse circuit.

[0012] The control module is used for parameter parsing, time compensation and signal acquisition, and reads the waveform and delay parameters stored in the waveform memory and sends them to the DDS module to generate trigger signals for each channel; the time difference measurement unit based on TDC measures the inherent trigger time difference between each channel in real time and accurately, and adopts a hybrid measurement architecture that combines coarse counting and fine counting to quantify the transmission position of the signal in the delay chain and feed it back to the control module for parameter correction.

[0013] The driving module is used to receive the trigger signal generated by the DDS module and quickly trigger the excitation Marx pulse circuit; the Marx pulse circuit receives the voltage signal from the driving module and generates a Gaussian pulse with extremely low time jitter.

[0014] The pulse shaping unit based on programmable microstrip lines is used to shape Gaussian pulses into single-cycle pulses and dynamically adjust the internal filtering structure according to changes in the array pattern and the underground focal point, so that the reconstructed single-cycle pulse is optimally matched with the current transmission direction in terms of center frequency, bandwidth, and time domain envelope.

[0015] As one embodiment, the transmitter further includes an antenna array and a power management module. The antenna array is used to radiate shaped single-cycle pulses to achieve directional focusing or scanning of underground targets. The power management module uses multi-phase interleaved parallel PWM technology to provide stable voltage for the Marx pulse circuit.

[0016] As one embodiment, the control module is an FPGA control board. The FPGA control board achieves precise phase delay control of the pulse signals between channels by adjusting the delay trigger period and the phase difference output by each DDS module, and compensates for the error caused by the inconsistency of the inherent trigger time of the channels.

[0017] The FPGA control board integrates a TDC (Time to Digital Conversion) module. The Marx pulse signal of each channel is fed back to the FPGA control board. The FPGA control board measures and obtains the trigger time difference between channels in real time, continuously compares the theoretical delay value with the TDC feedback value, and automatically updates the trigger period and DDS phase word before each transmission cycle to achieve picosecond-level adaptive phase error correction.

[0018] As one embodiment, the pulse shaping unit is a programmable microstrip line filter network, which consists of multiple diodes and microstrip line short-circuit branches of different electrical lengths. The on / off combination of each diode is controlled by a multi-bit control word output by the FPGA control board, which can switch between multiple pre-calibrated filter states and dynamically change the filter characteristics to shape the Gaussian pulse into a Gaussian single-cycle pulse with different center frequency, bandwidth and pulse width parameters.

[0019] As one embodiment, the pulse shaping unit uses various combinations of PIN diodes to form a set of digitally coded pulse waveform pattern tables, creating a pulse waveform library that can be called according to the detection environment and antenna radiation requirements.

[0020] As one embodiment, the pulse mode is selected by a waveform control word issued by the FPGA control board. The waveform control word is defined as a twelve-bit binary mask used to indicate the conduction state of each diode. The FPGA control board selects the corresponding shaping mode from the waveform library according to the target detection depth and the required center frequency, so that the transmitted pulse can achieve fine shaping of the spectral characteristics within the preset detection depth range.

[0021] According to some embodiments, the present disclosure adopts the following technical solutions:

[0022] A control method for a broadband phased array ground-penetrating radar transmitter includes:

[0023] The FPGA control board is initialized, and waveform control words are selected from the preset library based on the analysis results of underground medium parameters to match the current detection environment.

[0024] Entering the working mode selection stage: If a census task is to be performed, cyclic scanning phase delay parameters are generated; if a fixed-point detection is to be performed, directional focusing phase delay parameters are generated.

[0025] The FPGA control board loads the corresponding working mode according to the current detection task and issues control commands for initial phase delay parameters, delay trigger period, pulse width and waveform control word. After completing parameter parsing, the FPGA control board drives the DDS module to generate a trigger signal with a set phase difference and synchronously controls each channel drive module to excite the Marx pulse circuit to achieve high-power, high-consistency Gaussian pulse output.

[0026] The Gaussian pulse is shaped and reconstructed by a programmable microstrip network according to the waveform control word to obtain a transmit waveform that meets the requirements of the spectrum and time domain, and is then radiated by the antenna array;

[0027] The FPGA control board continuously corrects and issues parameter control commands based on the real-time measurement results of the time difference measurement unit based on TDC, thereby achieving high-precision timing closed-loop control.

[0028] According to some embodiments, the present disclosure adopts the following technical solutions:

[0029] A computer program product includes a computer program that, when executed by a processor, implements the control method for a broadband phased array ground-penetrating radar transmitter.

[0030] According to some embodiments, the present disclosure adopts the following technical solutions:

[0031] A non-transitory computer-readable storage medium is provided for storing computer instructions, which, when executed by a processor, implement the control method for a broadband phased array ground-penetrating radar transmitter.

[0032] According to some embodiments, the present disclosure adopts the following technical solutions:

[0033] An electronic device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to perform a control method for implementing a broadband phased array ground penetrating radar transmitter.

[0034] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0035] This disclosure discloses a control method for a broadband phased array ground-penetrating radar transmitter, which achieves high-power pulse transmission and picosecond-level beam control accuracy of the phased array ground-penetrating radar; realizes multi-channel transmission of instantaneous high peak power pulse signals, high-precision time delay control between channels, and directional focusing and cyclic scanning of the ground-penetrating radar electromagnetic beam, and adapts to the comprehensive detection requirements of different detection depths and imaging resolutions.

[0036] This invention discloses a broadband phased array ground-penetrating radar transmitter, comprising a control module, a time difference measurement unit based on TDC (Time-to-Digital Conversion), a pulse shaping unit based on programmable microstrip lines, a DDS (Direct Digital Frequency Synthesis) module, a drive module, a Marx pulse circuit, an antenna array, and a power management module. It employs a closed-loop feedback mechanism based on the TDC time difference measurement unit to compensate for the inherent trigger time difference between channels in real time, ensuring multi-channel synchronization of the transmitter. The pulse shaping unit based on programmable microstrip lines enables flexible shaping of Gaussian pulses into single-cycle Gaussian pulses with different center frequencies to adapt to detection requirements at different depths. A true-time-delay transmission architecture with a high-precision DDS-triggered, low-jitter Marx pulse source is constructed to effectively suppress dispersion problems during broadband signal beamforming. This invention achieves high-time-precision control and high-peak-power output of the transmitter, making it suitable for high-resolution phased array ground-penetrating radar systems.

[0037] This disclosure discloses a broadband phased array ground-penetrating radar transmitter that uses a TDC integrated on an FPGA control board to measure the trigger time difference of each channel in real time and automatically updates the DDS phase word before each transmission cycle, achieving picosecond-level multi-channel adaptive phase calibration. Therefore, the array can maintain strict phase consistency even during large-angle scanning and deep focusing, improving the focusing intensity and imaging resolution of underground targets.

[0038] The broadband phased array ground-penetrating radar transmitter disclosed herein employs a programmable microstrip line filter network, which forms a discrete selectable pulse waveform library through a combination of various diode branches. The FPGA control board adaptively selects a single-cycle pulse according to the target detection depth and underground medium conditions, thereby improving the echo signal-to-noise ratio and effectively suppressing sidelobes and interference.

[0039] This disclosure discloses a broadband phased array ground-penetrating radar transmitter. Through a designed structure of "differentiating circuit + radio frequency transformer + high-current drive + Marx cascade," it achieves ultra-wideband Gaussian pulses with sub-nanosecond pulse widths and instantaneous voltages exceeding kilovolts, with system time jitter less than 10 ps. The high peak power and extremely low jitter excitation source ensures the stability and repeatability of the phased array transmission, thereby improving the detection effect on deep and weakly reflective objects. Attached Figure Description

[0040] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure.

[0041] Figure 1 This is a diagram of the architecture of a broadband phased array ground-penetrating radar transmitter according to an embodiment of this disclosure;

[0042] Figure 2 This is a schematic diagram of the Marx pulse circuit in an embodiment of this disclosure;

[0043] Figure 3 This is a flowchart illustrating the control process of a broadband phased array ground-penetrating radar transmitter in an embodiment of this disclosure. Detailed Implementation

[0044] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0045] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0046] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0047] Example 1

[0048] One embodiment of this disclosure provides a broadband phased array ground-penetrating radar transmitter, which can realize multi-channel transmission of high peak power pulse signals, high-precision time delay control between channels, and directional focusing and cyclic scanning of electromagnetic beams. During the scanning process, it performs real-time analysis and adaptive focusing on the echo of underground targets, thereby taking into account the comprehensive performance of detection depth and imaging resolution.

[0049] like Figure 1As shown, a broadband phased array ground-penetrating radar transmitter disclosed herein includes a control module, a time difference measurement unit based on TDC (time-to-digital conversion), a pulse shaping unit based on programmable microstrip lines, a DDS (direct digital frequency synthesis) module, a drive module, a Marx pulse circuit, an antenna array, and a power management module. The control module is communicatively connected to the time difference measurement unit based on TDC (time-to-digital conversion), the pulse shaping unit based on programmable microstrip lines, the DDS (direct digital frequency synthesis) module, the drive module, the Marx pulse circuit, the antenna array, and the power management module.

[0050] As one embodiment, the control module is an FPGA control board used for parameter parsing, time compensation and signal acquisition, and reads the waveform and delay parameters stored in the waveform memory, and sends them to the DDS module to generate trigger signals for each channel. The time difference measurement unit based on TDC (time-to-digital conversion) is used to measure the inherent trigger time difference between each channel in real time and accurately. The time difference measurement unit adopts a hybrid measurement architecture of 'coarse counting + fine counting', and achieves picosecond-level time resolution by quantizing the transmission position of the signal in the delay chain.

[0051] Furthermore, the FPGA control board achieves precise phase delay control of the pulse signals between channels by adjusting the delayed trigger period and the phase difference output by each DDS module, and compensates for the error caused by the inherent inconsistency of the trigger time of the channels; the FPGA control board integrates a TDC time-to-digital converter module, and the Marx pulse signal of each channel is fed back to the FPGA control board. The FPGA control board measures and obtains the trigger time difference between channels in real time, continuously compares the theoretical delay value with the TDC feedback value, and automatically updates the trigger period and DDS phase word before each transmission cycle to achieve picosecond-level adaptive phase error correction;

[0052] Furthermore, the FPGA control board is configured to issue phase control words for each channel of the DDS based on the following formula (1):

[0053] (1)

[0054] in, The number of bits for the DDS phase accumulator. For signal frequency, The relative permittivity of the medium, For the first The path difference between the passage and the reference passage to the underground focal point. To delay the triggering period, The first one obtained by TDC measurement The inherent trigger time difference of the channel, the first The residual time of the inherent trigger time difference of the channel is .

[0055] Specifically, the DDS module receives delay control commands from the host computer via the FPGA control board and sends the corresponding four phase-controllable trigger signals to the four DAC chips through the JESD204B high-speed interface. By precisely adjusting the phase control words of the DDS signals of each channel, picosecond-level delay control of the pulse signals between channels can be achieved with an accuracy of up to 10 ps. Preferably, the DAC chip is the AD9168, which supports single-channel 16-bit digital-to-analog conversion and has a data conversion rate of 6 GSPS.

[0056] As one embodiment, the driving module is used to receive the trigger signal generated by the DDS module and quickly trigger the excitation Marx pulse circuit; the Marx pulse circuit receives the voltage signal from the driving module and generates a Gaussian pulse with extremely low time jitter.

[0057] Furthermore, the Marx pulse circuit adopts a multi-stage avalanche transistor cascade structure, including multiple capacitor units. Each capacitor unit includes a capacitor, an avalanche transistor, and a resistor. Voltage superposition is achieved through the series discharge of multiple capacitors, generating a high-voltage pulse with an instantaneous voltage exceeding kilovolts and a pulse width of sub-nanosecond. Preferably, the switching device is a transistor of model FMMT415 or FMMT417, which has the characteristics of fast response rate, low conduction loss, and high pulse voltage, and can achieve picosecond-level trigger synchronization accuracy.

[0058] like Figure 2 As shown, the Marx pulse circuit consists of 10 units connected in series: each energy storage capacitor C1-C1. 10 Through charging resistor R1-R 10 Power supply V CC Parallel charging; switching devices Q1-Q at each stage 10 The emitter is grounded, and the collector is connected to each stage of the energy storage node; the trigger pulse passes through the coupling capacitor C. b Added to the base of Q1 and by R b Leakage, between levels by C i The voltage jump in the preceding stage is coupled to the base of the following stage, in conjunction with R 11 -R 19 Pull-down switches enable cascaded conduction, changing the capacitor from parallel charging to series discharging, under load R. L The output at both ends is approximately N V CC A high-voltage pulse. Preferably, the V CC 300V, R1-R 10 For 100kΩ, R 11 -R 20 200kΩ, C1-C 10 It is 50pF.

[0059] Furthermore, the driving module includes an RC differentiating circuit, a driving chip, and an RF transformer; the RC differentiating circuit is used to convert the square wave signal into a spike pulse; the driving chip can generate a large driving current, has a sub-nanosecond rise time, and supports a high repetition frequency; the RF transformer is used for isolation and voltage boosting to achieve rapid turn-on of the Marx pulse circuit and suppress timing jitter.

[0060] As one embodiment, the driver chip generates a maximum current of 20A, with a pulse rise time of less than 4ns, and supports a high repetition frequency; the RF transformer is used for isolation and boosting to enable the rapid turn-on of the Marx pulse circuit, thereby suppressing timing jitter; preferably, the driver chip is a UCC27517ADBVR, and the RF transformer is a TC1-1+, which is suitable for driving the Marx pulse circuit.

[0061] The avalanche transistors used in the Marx pulse circuit have all undergone consistency screening, ensuring that the overall system time jitter is less than 10ps, thereby meeting the requirements of high-precision phase control; the Marx pulse circuit can output instantaneous voltages of thousands of volts and narrow pulse signals at the sub-nanosecond level;

[0062] As one embodiment, a pulse shaping unit based on a programmable microstrip line is used to shape a Gaussian pulse into a single-cycle pulse, and dynamically adjust the internal filtering structure according to the changes in the array pattern and the underground focal point, so that the reconstructed single-cycle pulse is optimally matched with the current transmission direction in terms of center frequency, bandwidth and time domain envelope.

[0063] As one embodiment, the pulse shaping unit of the programmable microstrip line is controlled by a host computer. Based on the required pulse waveform, it selects and sends the corresponding waveform control word, thereby enabling the selection of the microstrip line corresponding to the desired waveform. The programmability means that pulse shaping can be achieved through computer-controlled sending of the waveform control word.

[0064] The pulse shaping unit based on programmable microstrip lines is used to shape Gaussian pulses into single-period pulses to adapt to the radiation characteristics of the antenna array. The configuration of the pulse shaping unit is dynamically adjusted by the FPGA according to the preset array radiation optimization strategy, so that the spectral characteristics of the single-period pulses match the current transmission beam direction and the underground focusing point.

[0065] Furthermore, the pulse shaping unit is a programmable microstrip line filter network, which consists of multiple diodes and microstrip line short-circuit branches of different electrical lengths. The switching combination of each diode is controlled by the multi-bit control word output by the FPGA control board, which can switch between multiple pre-calibrated filter states, thereby dynamically changing the filter characteristics and shaping the Gaussian pulse into a Gaussian single-cycle pulse with different center frequency, bandwidth and pulse width parameters.

[0066] Furthermore, the pulse shaping unit uses various combinations of PIN diodes to form a set of digitally coded pulse waveform pattern tables, creating a pulse waveform library that can be called upon according to the detection environment and antenna radiation requirements.

[0067] Specifically, the pulse waveform mode is determined by the waveform control word issued by the FPGA control board. Select the waveform control word. Defined as a twelve-bit binary mask, it is used to indicate the conduction state of each diode; the FPGA control board selects the corresponding shaping mode from the waveform library according to the target detection depth and the required center frequency, so that the transmitted pulse can achieve fine shaping of the spectrum characteristics within the preset detection depth range.

[0068] As one embodiment, the antenna array is used to radiate shaped single-cycle pulses to achieve directional focusing or scanning of underground targets. Before the start of each transmission cycle, the FPGA control board selects the optimal pulse shaping state from a preset pulse waveform library based on the preset target beam pointing angle, underground focusing depth, and antenna array pattern parameters, and synchronously updates the delay triggering period, phase control word, and waveform control word of each channel, so that the transmission array simultaneously meets the desired directional gain and pulse spectrum characteristics in the target direction, thereby improving the resolution and signal-to-noise ratio of underground defects in that direction.

[0069] Based on the depth, angle, and distance information of underground defects, the control module calculates the corresponding trigger signal delay period, phase control word, and waveform control word, and selects the appropriate diode on / off combination from the waveform library of the pulse shaping module to achieve focused and repeated verification of underground defects.

[0070] As one embodiment, the channel i The phase difference compared to the reference channel is:

[0071]

[0072] The inter-channel trigger phase difference is:

[0073]

[0074] No. The phase difference of the residual period of the inherent trigger time difference of the channel is:

[0075]

[0076] Compensation for phase difference:

[0077]

[0078] The corresponding DDS phase control word is:

[0079]

[0080] in, The number of bits for the DDS phase accumulator. For signal frequency, The relative permittivity of the medium, For the first The path difference between the passage and the reference passage to the underground focal point. The first one obtained by TDC measurement The residual time of the inherent trigger time difference of the channel The delay trigger period is defined by the formula above. The FPGA control board can automatically update the delay trigger period before the start of each transmit cycle. and phase control word This ensures that the array maintains strict synchronization even under large scanning angles and high depth focusing.

[0081] As one embodiment, the power management module includes a DC power supply module, a boost module, a heat dissipation module, and a voltage regulation and filtering module. The power management module uses multi-phase interleaved parallel PWM technology to provide a stable voltage for Marx pulse electricity.

[0082] Furthermore, the DC power supply module is a 12V DC power supply used to power the FPGA, boost module, and heat dissipation module; the boost module adopts multi-phase interleaved parallel PWM technology to supply the Marx pulse circuit with 320V DC voltage, and has a very small ripple coefficient to reduce the timing jitter of the transmit link; the voltage regulation and filtering module is used to suppress the oscillation caused by stray capacitance and inductance in the circuit and improve the stability of the high-voltage link of the system.

[0083] As one embodiment, the operation process of a broadband phased array ground-penetrating radar transmitter disclosed herein includes:

[0084] The control module generates corresponding delay control commands based on the system's operating mode. In directional detection mode, the FPGA control board controls the array antenna to achieve directional beam focusing or cyclic scanning based on pre-calculated and stored phase delay parameters. In channel error calibration mode, the FPGA control board, based on a preset calibration procedure, acquires the inherent phase error between each channel in real time through the TDC module, and updates the adjustable delay compensation parameters and integer trigger period accordingly. K i This improves closed-loop synchronization accuracy. In focusing mode, the FPGA control board dynamically generates precise phase delay parameters and corresponding waveform mode indices for each channel based on the angle and distance information of suspected defective targets. WW iThis enables the array to focus on the target, and at the same time automatically selects the optimal single-cycle pulse from the waveform library shown in Table 1 for the target depth.

[0085] Table 1. Configuration diagram of the pulse waveform library

[0086]

[0087] Table 1 lists several sets of 12-bit binary masks and their corresponding center frequencies. Pulse width The recommended applicable detection depth range is also provided, with each row corresponding to a pre-calibrated single-cycle pulse pattern. Each mask is associated with a waveform control word issued by the FPGA. One-to-one correspondence, waveform control word Each bit indicates the on or off state of the corresponding PIN diode, thereby selecting different combinations of microstrip short-circuit branches to form various pulse waveforms. The control module can select a suitable waveform from the waveform modes shown in Table 1 based on the target detection depth and the required center frequency. The pulse shaping module is configured to enable the transmitted pulse to obtain matching spectral and temporal characteristics under different depth conditions.

[0088] like Figure 2 As shown, in the Marx pulse circuit provided in this embodiment, the DC power supply charges the capacitors at each stage through charging resistors. Upon triggering, the drive module outputs a sub-nanosecond spike pulse, turning on the first-stage avalanche transistor. Each stage is triggered sequentially, achieving a superimposed voltage output within a sub-nanosecond timeframe. The selected energy storage capacitor value is in the pF range, and the resistor value is in the kΩ range to balance charging time and pulse energy. The output pulse width is in the picosecond range, with a timing jitter of less than 10 ps. The transmission microstrip line undergoes rigorous impedance matching design, and electromagnetic interference is further reduced through optimized stack-up structure and metal shielding.

[0089] Example 2

[0090] One embodiment of this disclosure provides a control method for a broadband phased array ground-penetrating radar transmitter, including multiple steps such as system initialization, mode selection, multi-channel transmission and waveform reconstruction, and defect focusing and verification. The specific process includes:

[0091] The system performs FPGA initialization; at the same time, based on the analysis results of underground medium parameters, it selects waveform control words from the preset library to match the current detection environment;

[0092] Subsequently, the system enters the working mode selection stage: if a census task is performed, cyclic scanning phase delay parameters are generated; if a fixed-point detection is performed, directional beam-gathering phase delay parameters are generated.

[0093] The FPGA control board loads the corresponding operating mode according to the current detection task and issues the initial phase delay parameters and delay trigger period. K i Pulse width and waveform control word WW i The FPGA control board, after completing parameter parsing, drives the DDS module to generate a trigger signal with a set phase difference, and synchronously controls each channel drive module to excite the Marx pulse circuit, achieving high-power, high-consistency Gaussian pulse output; subsequently, the pulse is filtered by a programmable microstrip line filter network according to the waveform control command. WW i The waveform is shaped and reconstructed to obtain a transmission waveform that meets the requirements of the spectrum and time domain, and then radiated into the ground by the antenna array.

[0094] During this stage, the FPGA control board not only issues the aforementioned parameters, but also continuously corrects them based on the real-time measurement results of the TDC. The residual time of the inherent trigger time difference of the channel Delayed trigger cycle K i and phase control word PW i (This correction amount originates from the TDC's monitoring of the previous pulse signal transmission), thereby achieving high-precision timing closed-loop control. In addition, for specific abnormal areas, the FPGA control board supports entering a focused mode: by inputting the distance and angle of the defect, the FPGA control board calculates the delay parameters and directly updates the control commands to achieve precise point-to-point focusing of energy.

[0095] Example 3

[0096] One embodiment of this disclosure provides a computer program product, including a computer program that, when executed by a processor, implements the control method for a broadband phased array ground penetrating radar transmitter.

[0097] Example 4

[0098] One embodiment of this disclosure provides a non-transitory computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the control method for a broadband phased array ground-penetrating radar transmitter.

[0099] Example 5

[0100] One embodiment of this disclosure provides an electronic device, including: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to execute a control method for implementing a broadband phased array ground penetrating radar transmitter.

[0101] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0102] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0103] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A broadband phased array ground-penetrating radar transmitter, characterized in that, It includes a control module, a time difference measurement unit based on TDC, a pulse shaping unit based on programmable microstrip lines, a DDS module, a drive module, and a Marx pulse circuit; The control module is used for parameter parsing, time compensation and signal acquisition, and reads the waveform and delay parameters stored in the waveform memory and sends them to the DDS module to generate trigger signals for each channel; the time difference measurement unit based on TDC measures the inherent trigger time difference between each channel in real time and accurately, and adopts a hybrid measurement architecture that combines coarse counting and fine counting to quantify the transmission position of the signal in the delay chain and feed it back to the control module for parameter correction. The driver module is used to receive the trigger signal generated by the DDS module and quickly trigger the excitation Marx pulse circuit; The Marx pulse circuit receives a voltage signal from the drive module and generates a Gaussian pulse with extremely low time jitter. The pulse shaping unit based on programmable microstrip lines is used to shape Gaussian pulses into single-cycle pulses and dynamically adjust the internal filtering structure according to changes in the array pattern and the underground focal point, so that the reconstructed single-cycle pulse is optimally matched with the current transmission direction in terms of center frequency, bandwidth, and time domain envelope.

2. The broadband phased array ground-penetrating radar transmitter as described in claim 1, characterized in that, The transmitter also includes an antenna array and a power management module. The antenna array is used to radiate shaped single-cycle pulses to achieve directional focusing or scanning of underground targets. The power management module uses multi-phase interleaved parallel PWM technology to provide a stable voltage for the Marx pulse circuit.

3. The broadband phased array ground-penetrating radar transmitter as described in claim 1, characterized in that, The control module is an FPGA control board. The FPGA control board achieves precise phase delay control of the pulse signal between channels by adjusting the delay trigger period and the phase difference output by each DDS module, and compensates for the error caused by the inconsistency of the inherent trigger time of the channel. The FPGA control board integrates a TDC (Time to Digital Conversion) module. The Marx pulse signal of each channel is fed back to the FPGA control board. The FPGA control board measures and obtains the trigger time difference between channels in real time, continuously compares the theoretical delay value with the TDC feedback value, and automatically updates the trigger period and DDS phase word before each transmission cycle to achieve picosecond-level adaptive phase error correction.

4. A broadband phased array ground-penetrating radar transmitter as described in claim 3, characterized in that, The pulse shaping unit is a programmable microstrip line filter network, which consists of multiple diodes and short-circuit branches of microstrip lines with different electrical lengths. The on / off combination of each diode is controlled by a multi-bit control word output by the FPGA control board, which can switch between multiple pre-calibrated filter states and dynamically change the filter characteristics to shape the Gaussian pulse into a Gaussian single-cycle pulse with different center frequency, bandwidth and pulse width parameters.

5. A broadband phased array ground-penetrating radar transmitter as described in claim 1, characterized in that, The pulse shaping unit uses various combinations of PIN diodes to form a set of digitally coded pulse waveform pattern tables, creating a pulse waveform library that can be called according to the detection environment and antenna radiation requirements.

6. A broadband phased array ground-penetrating radar transmitter as described in claim 4, characterized in that, The pulse mode is selected by the waveform control word issued by the FPGA control board. The waveform control word is defined as a twelve-bit binary mask used to indicate the conduction state of each diode. The FPGA control board selects the corresponding shaping mode from the waveform library according to the target detection depth and the required center frequency, so that the transmitted pulse can achieve fine shaping of the spectral characteristics within the preset detection depth range.

7. A control method for a broadband phased array ground-penetrating radar transmitter according to any one of claims 1-6, characterized in that, The transmitter also includes an antenna array and a power management module. The control module is an FPGA control board, and the pulse shaping unit is a programmable microstrip line filter network, including: The FPGA control board is initialized, and waveform control words are selected from the preset library based on the analysis results of underground medium parameters to match the current detection environment. Entering the working mode selection stage: If a census task is to be performed, cyclic scanning phase delay parameters are generated; if a fixed-point detection is to be performed, directional focusing phase delay parameters are generated. The FPGA control board loads the corresponding working mode according to the current detection task and issues control commands for initial phase delay parameters, delay trigger period, pulse width and waveform control word. After completing parameter parsing, the FPGA control board drives the DDS module to generate a trigger signal with a set phase difference and synchronously controls each channel drive module to excite the Marx pulse circuit to achieve high-power, high-consistency Gaussian pulse output. The Gaussian pulse is shaped and reconstructed by a programmable microstrip line filter network according to the waveform control word to obtain a transmit waveform that meets the requirements of the spectrum and time domain, and is then radiated by the antenna array; The FPGA control board continuously corrects and issues parameter control commands based on the real-time measurement results of the time difference measurement unit based on TDC, thereby achieving high-precision timing closed-loop control.

8. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the control method for a broadband phased array ground-penetrating radar transmitter as described in claim 7.

9. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium is used to store computer instructions, which, when executed by a processor, implement the control method for a broadband phased array ground-penetrating radar transmitter as described in claim 7.

10. An electronic device, characterized in that, include: The device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to perform a control method for a broadband phased array ground penetrating radar transmitter as described in claim 7.

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