Optimizational Design Of Ground Penetrating Radar Hardware System

The ground penetrating radar(GPR)transmits and receives broadband electromagnetic waves underground,then performs operations such as amplifying,sampling,gain adjustment,and analog-to-digital conversion on the received signal,and finally performs post-processing on the obtained information to detect underground foreign objects.The hardware system is a key part of the GPR,which determines the quality of the information collected by the GPR.In view of the low imaging quality of the original GPR,this paper takes the hardware system of the GPR as the research object,analyzes the key issues in the improvement of the hardware performance of the GPR,proposes the optimization target of the hardware system,and implements the optimization and verification of the GPR hardware system,the main research contents are as follows:Firstly,the key issues of improving the hardware performance of the GPR are analyzed and the optimization target of the hardware system is proposed.According to the working principle of the GPR,through analyzing the imaging performance of the original GPR,clarified its problems such as the outdoor imaging contour is not clear,the grayscale image has large random noise,the grayscale background color is light and uneven and the grayscale image has large contrast in the depth direction,which in turn affects the performance indicators of the GPR.The optimization goal of the GPR hardware system is proposed.Then,a hardware optimization design scheme to improve the performance of GPR is proposed and verified.The principle of transistor avalanche effect is analyzed,the original Marx circuit is researched,and the emission limit current resistance is replaced with a fast switching diode,thereby reducing the energy loss of the Marx circuit,The problem of short life of Marx circuit is solved by replacing the original avalanche transistor,the pulse amplitude of GPR is increased by 6-level Marx circuit,and the repetitive working frequency of transmitter is increased;the principle of four-tube balanced sampling gate is analyzed,though adjusting the balance between the DC bias circuit and the sampling pulse to achieve the symmetrical control of the sampling gate;the limiting and amplification of the receiver's RF front-end is analyzed,based on the original voltage-controlled attenuator and low-noise amplifier,the nonlinear interval of the low-noise amplifier is used for the direct-coupled wave performs nonlinear amplification,and linearly amplifies the reflected wave of foreign objects,which realizes the selective amplification of the received signal.Finally,the GPR prototype with optimized hardware system was developed and the overall experiment was carried out.Based on the previous outdoor test experience,the overall structure of the GPR car was improved;on the basis of the original transceiver antenna,through experiments on replaceable components such as radio frequency transformers,the input VSWR of the transceiver antenna was optimized,and the tail of the main pulse of the reception waveform is reduced.Outdoor experiments were carried out on the whole machine,and the results showed that the optimized GPR prototype reached the design index.