Design And Implementation Of Ground Penetrating Radar Acquisition System Based On Random Equivalent Sampling Technique

Ground penetrating radar(GPR)is an instrument for geological structure detection,which is mainly applied to archaeology,road detection and logging.This paper mainly relies on the ground penetrating radar project which is applied to the side wall detection of oil drilling.The design and implementation of ground penetrating radar acquisition system based on random equivalent sampling technique are studied and analyzed under the condition of very small volume space and very wide temperature range.The design of GPR acquisition system is mainly introduced from the following aspects.1.Through the analysis of the working principle and system requirements of GPR,the acquisition system based on random equivalent sampling technique is designed,and all functions are realized by the state machine in FPGA,and the acquisition and reconstruction of radar echo signal are completed.2.Design high resolution time interval measurement circuit to achieve precise measurement of narrow pulse,and provide accuracy guarantee for correct reconstruction of waveform in random sampling process.The nonlinear problem of time measurement circuit is deeply analyzed,and the program is designed to realize the correction of time measurement circuit.3.Through the research and analysis of radar echo characteristics,we design high-speed trigger circuit to achieve stable acquisition of trigger pulses.Pre trigger function is designed to achieve functional requirements of sampling window.4.According to the demand of the temperature range of the collection system,a reasonable power distribution system is designed,and the voltage and current and temperature monitoring circuit are designed to realize the monitoring of the state of the acquisition system and avoid the misjudgement of the ground control system by the information collected in the abnormal state.5.Through the analysis of the demand for the distance and speed of the ground penetrating radar communication between the ground and the ground,the efficient and stable communication circuit and handshake protocol are designed to realize the data interaction.The attenuation and noise interference in signal transmission process are deeply analyzed.Through the debugging of each circuit and function module,the random acquisition system of bandwidth 700 MHz,equivalent sampling rate 10 GSPS and resolution 14 bit is realized on the PCB area of 28cm*3.6cm.The effective digit of the system has reached 9.1764 bit,and the correct acquisition of the ground penetrating radar echo signal is realized.