Millimeter Wave Detector Signal Processor Design

The echo signal and system noise in the 8 millimeter band detector, which works in self-heterodyne mode, are analyzed in this paper, and a signal processing circuit is simulated and designed, and FFT de-noising algorithm is adopted. The paper focuses on the research of low-noise design in system, analyzes and simulates the FFT de-noising algorithm, and implements the algorithm by programming in FPGA. These methods could improve Signal-Noise Ratio (SNR) and increase maximum detecting range to extend the time of Fuze Warhead matching.First of all, the equation of maximum range and characteristics of echo signal and noise in detector are discussed, and the way to increase maximum range and the sources of system noise are analyzed in detail.Secondly, the frequency measurement algorithm based on DFT is focused in the paper. De-noising algorithms are simulated with Matlab to improve SNR.The principle of over-sampling technique to improve SNR is also analyzed and simulated with Matlab, which provides principal base for actually using, and the de-noising effects at different sampling rates are compared.Thirdly, the low-noise design of pre-processing circuit is researched in detail. First, low-noise device is selected, the millimeter-wave front-end is matched with an amplifier by using the best noise-matching method. Second, the differential method is used to reduce noise further to improve the capacity of resisting disturbance. The low-noise amplifier is simulated with Multisim. Appropriate A/D chip is chosen to use over-sampling technology to improve SNR.Finally, signal processing circuit is designed with Spartan-3E series FPGA provided by Xilinx as a hardware development platform. The algorithm, frequency measurement and actual debug are enforced with Verilog HDL program in ISE eventually. Experiment results are shown in last chapter.