Design And Implementation Of The Stepped-frequency Through-wall Radar Data Acquisition And Preprocessing System

The through-wall radar(TWR) which can penetrate the walls, bunkers and other shelters and detect the person concealed behind the wall uses the step frequency technique to achieve the ultra-wideband(UWB) signals. It is very important in applications such as military operations, counter-terrorism operations, disaster relievement and the other areas. However, the environment clutters overlap the through-wall radar echoes greatly. The cultter sources include the direct reflect signals from the wall, the coupling signal from the transmitter antenna,the radio frequency interferences from thewireless television and mobile communication devices in the VHF / UHF bands and the multipath reflections of the buildings. Consequently it is very difficult to detect the desired signals from the background.In order to obtain a wider range of echo signals, the best solution is by means of high speed and large dynamic range data acquisition system. From the point of view of the performance for the data acquisition system, this paper analyzes impacts of various factors on the data acquisition system, and proposes the corresponding solutions. Based on the high speed and large dynamic range data acquisition system, the paper mainly focused on the following three aspects of the work:(1)The paper analyzes the factors affecting the dynanmic range of the data acquisition and preprocessing system for stepped-frequency through-wall radar system. It proposes a designing scheme of the stepped-frequency through-wall radar data acquisition and preprocessing system and implements a system with a sample rate of 65 MHz and ENOB(the Effective Number of Bit) of 11.9 bits and a low power dissipation of 5 W.(2)The research on the Dither technology. In order to reduce the quantization noise influence on system frequency harmonic and burr, the paper researches the application of Dither technology in the ADC for the improvement on dynamic performance.(3)Research the test methods for figures of merit for specifying performance of high speed ADC and evaluate the performance of the data acquisition and pretreatment system. Through the study of dynamic performance test method, It has a feasible design of an experiment and achieves the Signal-to-Noise Ratio(SNR), the Signal-to Noise and Distortion Ratio(SNDR), the Effective Number of Bit(ENOB), and the Spurious Free Dynamic Range(SFDR).Then, analyze and verify the effect of aperture jitter on the system dynamic range by designing the experiment tested the aperture jitter.