Design And Research Of High Speed Receiver For UWB Through-wall Radar System

Through-wall radar(TWR)is a type of ultra-wideband radar.This radar system transmits and receives ultra-wideband narrow pulse signals.Based on the characteristics of this narrow pulse and wide frequency band,TWR has high range resolution and ultralong detection The natural advantage of distance,which makes UWB radars have excellent application value in many fields: for example,in military anti-terrorism operations,terrorists inside buildings can be detected and even weapons information carried by terrorists can be detected to help combat Personnel determine the type of weapon;in disaster search and rescue such as earthquakes,radar can penetrate collapsed obstacles to detect life characteristics,helping search and rescue personnel locate the life being rescued more quickly.The role of the wall-penetrating radar receiver is to convert the analog narrow pulse signal into digital signals through sampling technology to facilitate signal processing.This thesis from the theoretical demonstration to the design practice,has realized the entire wall-penetrating radar receiver system and improved the receiver to varying degrees The performance of each module.This thesis designs a new bipolar pulse generating circuit.The new bipolar pulse generation circuit abandons the traditional circuit structure that uses the balun to generate bipolar pulses.The bipolar pulse directly generated by the step recovery diode has a higher amplitude and a narrower pulse width.In addition,a shaping circuit is added at the back end of the circuit It not only ensures the high amplitude and narrow pulse width of the bipolar pulse signal,but also further adjusts the phase consistency of the two pulse signals,thereby overall optimizing the performance of the bipolar pulse signal generating circuit.This thesis designs a high-speed and stable sample-and-hold circuit.Firstly,the fourtube balanced gate is selected as the sampling gate device through theoretical demonstration,and then a multi-stage amplification filter circuit is designed to optimize the amplification filter effect of the circuit.In addition,a sample-and-hold chip controlled by digital signals is introduced to realize the digital control of signal-holding.In addition,a multi-stage amplification and filtering circuit is added after the sample-and-hold chip to further ensure the authenticity of the sampled signal.After the integration and improvement of the entire circuit,the new sample-and-hold circuit has more excellent performance,and can achieve picosecond sampling resolution.This thesis has designed the sequential control circuit based on FPGA.Firstly,the combination of high-precision fine delay chip and large-range coarse delay chip is used to realize a digital step delay circuit with high precision,large-range and easy control based on FPGA.Then,an electric scanning circuit based on FPGA control is designed to control the output of five signal sources to realize stable and accurate electronic scanning function.Finally,the communication protocol between the FPGA and the host computer is designed with emphasis,so that the FPGA can correctly recognize the transmission instructions and realize high-precision real-time control of the entire system.