Font Size: a A A

Design And Research Of Impact Type Ground Penetrating Radar

Posted on:2018-10-02Degree:MasterType:Thesis
Country:ChinaCandidate:C Y ChengFull Text:PDF
GTID:2348330518456800Subject:Radio Physics
Abstract/Summary:PDF Full Text Request
Ground penetrating radar(GPR)is an effective nondestructive detecting instrument and has a wide application prospect in geological exploration.Among the various structures of ground penetrating radar,impact type ground penetrating radar(GPR)is widely used because of its simple structure and good detection effect.This paper mainly studies the pulse source and data acquisition system of impact ground penetrating radar.In order to simplify the structure of the system,improve the performance of the system and reduce the power consumption of the system,a design scheme based on FPGA and MCU architecture is proposed.The scheme uses FPGA as the master chip,MCU auxiliary system communication and power control,which not only ensures the system's good performance,but also has excellent low power consumption characteristics.The transmitter of impulse ground penetrating radar needs a high power ultra wideband pulse.The system adopts the design of avalanche transistor to realize ultra wideband pulse.Based on the analysis of the breakdown characteristics of the avalanche transistor,a bipolar pulse source circuit is designed and fabricated.The experimental test shows that the maximum output pulse can reach 100 V and the pulse width is 7ns.The data acquisition system adopts the design of equivalent sampling.In order to avoid the design of high speed sampling gate,the idea of controllable time delay device and wideband analog to digital converter is adopted in the equivalent sampling and sampling.The programmable time delay device is MC100EP196 and the analog to digital converter is AD9629.The minimum delay step of MC100EP196 is 10 ps,so the equivalent sampling rate of the system can reach 100GSa/s in theory.In the design of this part,(1)the feasibility of the system scheme is analyzed on the basis of detailed description of the equivalent sampling principle;(2)the equivalent sampling control system is designed by FPGA.Through the high-speed FPGA logic design,precision delay and coarse delay adjusting acquisition clock,and transmitting trigger synchronous sampling clock pulse and the realization of the data acquisition of radar echo;(3)the front protection circuit design,the circuit adopts the diode limiter circuit,the input end of the input pulse allows the highest reached nearly 100 V.Thus,the acquisition system can be used to transmit and receive an antenna system.(4)use STM32F103 as the power management module of radar,cut off the power supply of transmitter and data acquisition module in long time without receiving the work order or receive the stand-by command,and realize the low power consumption of the system.In order to test the performance of the system,a series of tests were carried out.Including the integrity of the clock signal testing,data acquisition system testing.According to the result of test and the result of collecting echo,it is proved that the scheme can collect the echo of low frequency ground penetrating radar,and the test result is good when the equivalent sampling rate is 20GSa/s.
Keywords/Search Tags:ground penetrating radar, ultra wide impulsive source, FPGA, data acquisition system, delay chip
PDF Full Text Request
Related items