Pulse Generator And Data Acquistion System Of Ground Penetrating Radar

The subjects of impulse ground penetrating radar(GPR) system are discussed inthis paper: the study of pulse generator based on semiconductor switch, the study ofequivalent data acquisition based on Field Programmable Gate Array（FPGA）.As the study of the pulse generator, three works are reported.The first, describedthe main parameters and basic composition of the pulse generator. The second, developand test pulse generator based on avalanche transistor. This type of pulse generator’speak voltage more than1kV(50), rising time less than300ps. On the experiment ofaccelerate the falling edge, the unsmooth of the falling edge was founded though thedata and tested waveform. Discussed the reason why the pulse generator basedavalanche effect have oscillation during the falling time and proposed a method toweaken influence of the oscillation effect of the falling edge. Finally, designed a pulsesharpen circuit based on step recovery diode by using circuit simulation softwarePSPICEAs the study of the equivalent data acquisition, five works are reported. firstly,introduced the principle of the data acquisition the plan of equivalent data acquisition inthis paper. Secondly, analyzed time delay method of the equivalent data acquisition andverified the accuracy time delay of the Delay Locked Loop (DLL)’s multiple outputscan reach60ps based on FPGA. Thirdly, introduced the theory of the Track and Hold(T/H) circuit and described the T/H chip and analog to digital converter (A/D) chipwhich used in this paper. Fourthly, designed the program of the FPGA in which includestate machine, trigger signal control, chip control signal and pre-processing of the A/D.Finally, introduced the experiments of the equivalent data acquisition designed by thispaper which include FPGA program testing, the jitter of FPGA testing, S/H testing andequivalent data acquisition testing.