Novel dual-frequency three-dimensional ground penetrating radar acquisition system and method

Abstract

The invention provides a novel dual-frequency three-dimensional ground penetrating radar acquisition system and method. Comprising an FPGA main control unit used for controlling a dual-frequency antenna array, the dual-frequency antenna array used for receiving and transmitting dual-frequency radar detection pulses, a data acquisition unit, an Ethernet switch and an upper computer. The system adopts an antenna array design of two frequencies, is high in integration level, can efficiently perform large-area scanning and complete structure detection of different depths, has different detection precision, is uniform in measuring line interval and good in profile data consistency, and can fully ensure imaging and detection effects. The invention also provides a control method of the novel dual-frequency three-dimensional ground penetrating radar acquisition system.

Description

Technical Field

[0001] The present invention relates to the field of ground penetrating radar technology, and in particular to a novel dual-frequency three-dimensional ground penetrating radar data acquisition system and method. Background Art

[0002] As a recognized non-destructive testing tool, ground penetrating radar has been widely used in highway damage detection, and can effectively detect settlement, looseness, voiding, water-rich, cavities and other diseases. The advantages of three-dimensional ground penetrating radar technology are obvious: it can collect high-density, seamlessly spliced ​​massive radar data without causing the loss of underground information; true three-dimensional acquisition; it can make the underground target body image clear and accurate, and its three-dimensional data body can realize horizontal slice display at any depth.

[0003] At present, the antenna arrays equipped by many three-dimensional ground penetrating radar systems used for highway damage detection are only single-frequency. For the detection of roadbed thickness and internal defects in the field of highway detection, it is necessary to meet the requirements of high-precision resolution and detection depth. At this time, it is necessary to use different frequency antennas to replace the corresponding frequency antenna arrays to repeatedly scan the detection area. The detection speed is slow, the efficiency is low, the measurement line is difficult to control, it is not conducive to target imaging, and the three-dimensional data measured by antenna arrays of different frequencies are difficult to compare and process. Summary of the invention

[0004] The present invention aims to provide a novel dual-frequency three-dimensional ground penetrating radar data acquisition system and method, which adopts a two-frequency antenna array design and can simultaneously complete structure detection at different depths. It has high detection accuracy, uniform measurement line spacing, good profile data consistency, and can fully guarantee imaging and detection effects.

[0005] The technical solution of the present invention is implemented as follows: A novel dual-frequency three-dimensional ground penetrating radar data acquisition system, characterized in that it includes: an FPGA main control unit for controlling a dual-frequency antenna array, a dual-frequency antenna array for transmitting and receiving dual-frequency radar detection pulses, a data acquisition unit, an Ethernet switch and a host computer;

[0006] The FPGA main control unit includes a communication circuit, a data acquisition enabling and control circuit, a delay stepping circuit, and a switch switching circuit;

[0007] The dual-frequency antenna array includes two rows of high and low frequency antenna arrays, which are arranged crosswise in sequence, wherein the low frequency antenna array is arranged in the first row and includes 4 transmitting and 5 receiving antennas, generating 8 channels of low frequency echo data, and the high frequency antenna array is arranged in the second row and includes 9 transmitting and 8 receiving antennas, generating 16 channels of high frequency echo data, a total of 13 transmitting and 13 receiving antennas, each transmitting antenna and the adjacent receiving antenna are combined into a ground penetrating radar channel, generating a total of 24 channels of echo data;

[0008] The data acquisition unit is used for sampling echo data of the dual-frequency antenna array, and includes four single-chip module groups;

[0009] The Ethernet switch is used as a data communication transfer station, connected to the host computer, data acquisition unit and FPGA main control unit with network cables, and assigned different static IP addresses;

[0010] The host computer is used to receive the echo data of the data acquisition unit, and to perform parameter setting and acquisition state control, data imaging and storage with the FPGA main control unit.

[0011] The single-chip microcomputer module includes a communication circuit, a data acquisition enabling and control reading circuit, and a data acquisition circuit; the communication circuit is used for each single-chip microcomputer to send 6-channel dual-frequency antenna array echo data, and is connected to the Ethernet switch through a network cable; the data acquisition enabling and control reading circuit is used to enable sampling data and control sending data, and is connected to the FPGA main control unit data acquisition and enabling circuit; the data acquisition circuit is used to sample the echo signal, and each single-chip microcomputer module is connected to a 6-channel echo signal.

[0012] The FPGA main control unit communication circuit is used to receive the setting parameters and control commands of the host computer; the data acquisition enable and control circuit is used to generate data acquisition enable timing and data sending command timing, and is connected to the data acquisition enable and control reading circuit; the step delay circuit is used to generate step delay; the switch switching circuit is used to select the corresponding channel pulse pair, including 13 transmitting switches and 13 receiving switches; the step delay circuit and the switch switching circuit are used in combination to generate 13 receiving pulses and 13 transmitting pulses, forming 24 transmitting and receiving pulse pairs.

[0013] The 13 receiving pulses of the FPGA main control unit are connected to 13 receiving antennas, and the 13 sending pulses are connected to 13 transmitting antennas.

[0014] The FPGA main control unit is connected to the Ethernet switch via a network cable, receives the setting parameters of the host computer, and stores them in the register of the FPGA. The setting parameters include: sampling frequency, number of sampling points, and step delay.

[0015] The transmit and receive pulse pairs of different channels are not generated at the same time, so antennas of different channels can be controlled to work at different times to avoid mutual interference between antennas.

[0016] The dual-frequency antenna array generates 24 echo signals on 13 receiving antennas according to the transmit-receive pulse pairs generated by the FPGA main control unit and transmits them to the data acquisition circuit of the corresponding single-chip microcomputer.

[0017] The present invention provides a novel dual-frequency three-dimensional ground penetrating radar data acquisition, including: a host computer sends the setting parameters of each channel to an FPGA main control unit, and the FPGA main control unit obtains a sampling period according to a sampling frequency. First, a sampling period is equally divided into 13 switching periods, and in each switching period, a transmitting switch is turned on, and other transmitting switches are turned off, and the corresponding receiving switches are turned on at the same time.

[0018] A step delay digital quantity and a data acquisition enable timing sequence are generated within the switching cycle.

[0019] The order in which the transmitting switches are opened is KT1, KT4, KT7, KT10, KT113, KT2, KT5, KT8, KT11, KT3, KT6, KT9, and KT12.

[0020] The receiving switches are opened in the order of KR1, KR3&KR4, KR6&KR7, KR9&KR10, KR12&KR13, KR1&KR2, KR4&KR5, KR7&KR8, KR10&KR11, KR2&KR3, KR5&KR6, KR8, KR11&KR12. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention;

[0021] Figure 2 It is a schematic diagram of the microcontroller module;

[0022] Figure 3 This is a schematic diagram of the dual-frequency antenna array arrangement;

[0023] Figure 4 It is a schematic diagram of the trigger timing of the switch switching unit; Specific implementation method:

[0024] The specific technical solutions of the present invention are further described below so that those skilled in the art can further understand the present invention, but it does not constitute a limitation on the rights thereof.

[0025] The FPGA master control unit stores the channel step delay and other parameters of each frequency according to the setting parameters of the host computer, and generates the timing interval according to the sampling frequency, sampling point number and other parameters of the host computer setting parameters. For example, if all frequency antenna arrays are set to work simultaneously and the sampling frequency is 200KHz, then the sampling period of each channel will be 1 / (200KHz)=5us, and all logic control and data reading and output of 24 channels will be completed within 5us. Taking the transmitting antenna as the reference, one transmitting antenna is turned on at the same time as two receiving antennas, then the actual working time of a single channel is 5us / 13=0.3846us, that is, this sampling period is divided into 13 switching periods, and one transmitting switch and the adjacent receiving switch are turned on in each switching period. The order in which the transmitting switches are opened is KT1, KT4, KT7, KT10, KT113, KT2, KT5, KT8, KT11, KT3, KT6, KT9, KT12, and the corresponding order in which the receiving switches are opened is KR1, KR3&KR4, KR6&KR7, KR9&KR10, KR12&KR13, KR1&KR2, KR4&KR5, KR7&KR8, KR10&KR11, KR2&KR3, KR5&KR6, KR8, KR11&KR12. In a switching cycle, the FPGA main control unit first completes the generation of the step delay amount, and generates a pulse pair with the switch state combination, then pulls up the data acquisition enable timing, and the single-chip microcomputer module collects data according to the rising edge of the data acquisition enable timing, and completes the collection of one point of the channel in a switching cycle; switches to the next switching cycle, completes the collection of one point, until all 24 channels are collected in 13 switching cycles; then loops according to the number of sampling points until all channel data are collected, and obtains the data of the sampling points set by the host computer parameters, and stores them in the queue of each single-chip microcomputer module; sends the data acquisition control timing while looping the sampling points, and each single-chip microcomputer module sends the data to the Ethernet switch for the host computer to receive after obtaining the data acquisition control timing; then the next data collection begins.

Claims

1. A new dual-frequency three-dimensional ground penetrating radar data acquisition system, characterized in that: include: An FPGA main control unit for controlling a dual-frequency antenna array, a dual-frequency antenna array for transmitting and receiving dual-frequency radar detection pulses, a data acquisition unit, an Ethernet switch and a host computer; the FPGA main control unit includes a communication circuit, a data acquisition enabling and control circuit, a delay stepping circuit, and a switch switching circuit; the dual-frequency antenna array includes two rows of high and low frequency antenna arrays, which are arranged in a cross-sequence, wherein the low frequency antenna array is arranged in the first row and includes 4 transmitting and 5 receiving antennas, generating 8 channels of low frequency echo data, and the high frequency antenna array is arranged in the second row and includes 9 transmitting and 8 receiving antennas, generating 16 channels of high frequency echo data Data, a total of 13 transmitting and 13 receiving antennas, each transmitting antenna and the adjacent receiving antenna are combined into a ground penetrating radar channel, generating a total of 24 channels of echo data. The data acquisition unit is used for echo data sampling of the dual-frequency antenna array, including four single-chip module groups; the Ethernet switch is used as a data communication transfer station, and is connected to the host computer, the data acquisition unit and the FPGA main control unit with a network cable, and different static IP addresses are assigned; the host computer is used to receive the echo data of the data acquisition unit, and to perform parameter setting and acquisition status control with the FPGA main control unit, and data imaging and storage.

2. A novel dual-frequency three-dimensional ground penetrating radar data acquisition system according to claim 1, characterized in that: The single-chip microcomputer module includes a communication circuit, a data acquisition enabling and control reading circuit, and a data acquisition circuit; the communication circuit is used for each single-chip microcomputer to send 6-channel dual-frequency antenna array echo data, and is connected to the Ethernet switch through a network cable; the data acquisition enabling and control reading circuit is used to enable sampling data and control sending data, and is connected to the FPGA main control unit data acquisition and enabling circuit; the data acquisition circuit is used to sample the echo signal, and each single-chip microcomputer module is connected to a 6-channel echo signal.

3. The novel dual-frequency three-dimensional ground penetrating radar data acquisition system according to claim 1 is characterized in that: The FPGA main control unit communication circuit is used to receive the setting parameters and control commands of the host computer; the data acquisition enable and control circuit is used to generate data acquisition enable timing and data sending command timing, and is connected to the data acquisition enable and control reading circuit; the step delay circuit is used to generate step delay; the switch switching circuit is used to select the corresponding channel pulse pair, including 13 transmitting switches and 13 receiving switches; the step delay circuit and the switch switching circuit are used in combination to generate 13 receiving pulses and 13 transmitting pulses, forming 24 transmitting and receiving pulse pairs.

4. The novel dual-frequency three-dimensional ground penetrating radar data acquisition system according to claim 1 is characterized in that: The 13 receiving pulses of the FPGA main control unit are connected to 13 receiving antennas, and the 13 sending pulses are connected to 13 transmitting antennas.

5. The novel dual-frequency three-dimensional ground penetrating radar data acquisition system according to claim 1 is characterized in that: The FPGA main control unit is connected to the Ethernet switch via a network cable, receives the setting parameters of the host computer, and stores them in the register of the FPGA. The setting parameters include: sampling frequency, number of sampling points, and step delay.

6. The novel dual-frequency three-dimensional ground penetrating radar data acquisition system according to claim 3 is characterized in that: The transmit and receive pulse pairs of different channels are not generated at the same time, so antennas of different channels can be controlled to work at different times to avoid mutual interference between antennas.

7. The novel dual-frequency three-dimensional ground penetrating radar data acquisition system according to claim 1 is characterized in that: The dual-frequency antenna array generates 24 echo signals on 13 receiving antennas according to the transmit-receive pulse pairs generated by the FPGA main control unit and transmits them to the data acquisition circuit of the corresponding single-chip microcomputer.

8. A novel dual-frequency three-dimensional ground penetrating radar data acquisition method according to any one of claims 1 to 7, characterized in that: include: The host computer sends the setting parameters of each channel to the FPGA main control unit, and the FPGA main control unit obtains the sampling period according to the sampling frequency. First, a sampling period is divided into 13 switching periods. In each switching period, one transmitting switch is turned on, the other transmitting switches are turned off, and the corresponding receiving switches are turned on at the same time.

9. The novel dual-frequency three-dimensional ground penetrating radar data acquisition system according to claim 8, characterized in that: A step delay digital quantity and a data acquisition enable timing sequence are generated within the switching cycle.

10. The novel dual-frequency three-dimensional ground penetrating radar data acquisition system according to claim 8, characterized in that: The order in which the transmitting switches are opened is KT1, KT4, KT7, KT10, KT113, KT2, KT5, KT8, KT11, KT3, KT6, KT9, and KT12.

11. The novel dual-frequency three-dimensional ground penetrating radar data acquisition system according to claim 8, characterized in that: The receiving switches are opened in the order of KR1, KR3&KR4, KR6&KR7, KR9&KR10, KR12&KR13, KR1&KR2, KR4&KR5, KR7&KR8, KR10&KR11, KR2&KR3, KR5&KR6, KR8, KR11&KR12.

Images