Research On Key Techniques Of Equivalent Sampling Receiver In Through-Wall Radar

The Through-Wall Radar(TWR) which can penetrate nonmetal obstacles like walls has become a hot spot in the domestic and overseas, with several widespread military and civilian applications, such as anti-terrorism, rescue and surveillance missions. With the advantage of strong penetration, high resolution, and low probability of intercept, the impulse radar is widely applied to the TWR system.For the TWR receiver, the received signal is the UWB impulse signal, so the cost will be high if this signal is sampled in real-time sampling method. However the equivalent sampling technique can degrade the difficulty of the ultra-high speed sampling and reduce the cost. Therefore the equivalent sampling technique is the inevitable choice of the TWR receiver.The second chapter introduces the equivalent sampling technique in the TWR system. First of all, the TWR system is described, and the signal form and the frequency range are emphatically analysed. And then the UWB pulse waveform is analysed and simulated. Finally, the basic theory of the equivalent sampling technique is described.The third chapter introduces and discusses the design of the equivalent sampling receiver based on the traditional structure. First of all, the three key techniques which include the sampling gate circuit, the sampling pulse generator and the precision delay circuit are analysed. And then the novel sampling pulse generator is designed and fabricated based on the design target of the TWR, attaining the high-amplitude and narrow sampling pulse. Besides the novel precision delay circuit is designed and simulated, implementing the pulse of the high-precision and wide delay range. Good agreement between the measured and the simulated results is achieved.The fourth chapter discusses the design of the equivalent sampling receiver based on the Monolithic Microwave Integrated Circuit(MMIC). First of all, the equivalent sampling techniques are optimized. And then the novel the equivalent sampling receiver is designed and simulated based on the HMC660LC4 B, which is the track and hold MMIC chip. Good agreement between the analysed and the simulated results is also achieved, and it proves the validity of the novel design.