The Design Of High Speed Receiver System

Radar system based on impulse power is a kind of ultra-wideband radar. It posses abilities such as high resolution, good anti-stealth capability, low power consumption, good security, simple structure etc. Therefore, it’s been widely used in borehole imaging, medical imaging, through-wall imaging etc. Borehole radar system based on impulse power is extensively used in stratum exploration. The system achieved stratum exploration by receiving the reflected signal which generated by Marx impulse power.The receiving of radar reflected signal is achieved by receiver. It’s used to hold and amplify signals, and then convert analog signals to digital one. To receive signals data accurately, the receiver is required to have high rate as well as high resolution.This paper mainly discussed the design of the equivalent sampling receiver of borehole radar system based on impulse power. The signal bandwidth and transmitting frequency of the system is 1GHz and 10 kHz, respectively. As the radar is used as borehole radar, high resolution of receiving system is needed for imaging. Thus, the radar receiver is required to possess fast sampling speed, high resolution and broad bandwidth for data acquisition. The receiver proposed in this paper is with 1GHz bandwidth, 14 bits resolution and 100 kHz real time sampling rate. The sampling rate could reach 4GHz as equivalent sampling rate by delaying receiving time.The main components of this receiver are sample-and-hold circuit, operational-amplified circuit, bipolar pulse generating circuit and analog digital convertor. Sampling gate, actuated by the bipolar pulse generated by bipolar pulse generating circuit, samples and holds the target signal. Then the signal is amplified in-phrase by operational-amplified circuit first and converted to digital after that. High speed receiving could be realized by bipolar pulse generation time control of FPGA. The equivalent sampling rate could reach 4GHz.The paper discussed following aspects of the whole equivalent sampling receiver: the principle of data acquisition system, design of the circuit modules, selection of circuit components, design and simulation of bipolar impulse generator, test of sample and hold circuit, and test of receiver.