Experimental Study On RF Digital Receiver

In the radar system, it is the development direction to place digital processing, i.e., ADC and DAC, of the receiving system as close as possible to the antenna. It is the key technology of realizing fully digitalized radar. Direct digitization at IF is widely used and it is practicable now from laboratory that directly placing ADC or DAC near antenna at GHz carrier frequency. With the development of technology of high speed ADC, DAC and digital signal processing, it can make digitization in meter wave band at RF possible.The dissertation describes the implementation of RF digital receiving subsystem of meter wave band. The main content is as follows:1. This dissertation describes the correlative principle of the receiving technology of RF digitization, matched filtering, signal sampling and quantifying, quadrature demodulation, multi-Rate signal processing and digital filter; analyzing the fundamental performances and distortion types of the key chip-ADC.2. It is proposed that the design of receiving channels should take full advantage of the ADC’s performances to reach the best design of system’s sensitivity and instantaneous dynamic range during the digitalization receiving subsystem. The relationships between ADC and system’s sensitivity&dynamic range are analyzed and the design methodology and bases are proposed.3. The hardware design proposal of the RF digital receiver based on FPGA is proposed. The engineering implementation methods of high efficiency digital I/Q formation based on bandpass sampling theorem are proposed. The fundamental guidelines for high speed data transmission and digital-analog mixing circuit design are put forward.4. The effects of the performances of the sampling clock on RF digital receiver are analyzed and the design bases of sampling clock are proposed.5. The hardware design of the RF digital receiver is fulfilled and the test results are presented.