Design And Implementation Of High Resolution GPR System Based On TIADC Technology

The problem of road damage has become increasingly serious in recent years.It is particularly important to quickly and accurately obtain information on the road surface and under the road surface so as to grasp the quality and life cycle of the road under the premise of not damaging the road structure and affecting the normal driving speed of the vehicle.However,the current ground penetrating radar system that can be used for road detection at home and abroad cannot fully meet the requirements of high-speed detection due to the limitations of the sampling method,sampling rate,pulse width,ground coupling antenna installed close to the detection surface,antenna,and heavy mechanical structure.In order to overcome these defects,a high-resolution ground penetrating radar system based on TIADC technology is designed and developed.The specific work includes:(1)designing a UWB pulse generation circuit based on the switching characteristics of avalanche transistors.According to actual tests,the pulse width of the bottom of the pulse signal generated by this circuit is 2ns and the signal amplitude is 11 V.(2)In order to solve the traditional TIADC mismatch error and other problems,this paper proposes an improved data acquisition system based on TIADC technology.Control multi-phase clock gating by FPGA,drive high-speed ADC chip to achieve parallel alternate sampling of the same analog signal,and buffer the collected data in FIFO for reorganization.The acquisition system uses FPGA as the core and controls the work of various parts of the system,including SPI interface gain control,multiple sampling clock strobe,data cache storage implementation,UDP transmission,and high-speed ADC control,which implements the collection and caching of GPR data And transmission,after the collected ground penetrating radar data is transmitted to the computer through the UDP protocol,the saved data can be processed and analyzed,and the QT-based ground penetrating radar interface display is designed to facilitate observation of the collected data echo signal waveform.(3)Designed and produced a Vivaldi antenna from 300 MHz to 2GHz.The test results show that the return loss of the Vivaldi antenna is better than-10 d B,the radiation efficiency can be up to 99%,and the antenna's return gain can be up to 9.2d B.Based on the above technology,this paper completes the design of the entire GPR software and hardware system,including UWB pulse signal generator,data acquisition system,antenna,FPGA control system,and host computer.The experimental results show that the ground penetrating radar system designed in the thesis has the capability to detect the target body.The time required for the ground penetrating radar system to collect echo data is 800 ns,and the equivalent sampling frequency is 5GHz,which meets the needs of quickly collecting underground media information.