Design Of Signal Processing Circuits For Linear Frequency Modulation Detection System Which Is Based On FPGA

Based on the principles of digital IF radio, the hardware and the software of the signal processing circuit of the millimeter wave FM ranging system,which are implemented on a FPGA chip based on the range gates, are discussed in this paper. The system can measure a distance between Om and 20m.The computation of the parameters of the Triangular wave FM signal such as transmition frequency fo, frequency offset AFm, modulation frequency fm and the basic theory of the FIR digital filter are introduced in this paper. The design of the hardware with a Xilinx XC3S400 FPGA chip is also described. In the software design section,3dB bandwidth, minimum stop-band attenuation and other parameters of the five-channel FIR filter are calculated. The FIR filter tap coefficients which meet the requirements are calculated by calling the Matlab filter design functions such as firl and Kaiserord. How to design the five-channel FIR filter in Verilog on the XC3S400 chip is discussed later. The system is simulated with the tool of Test Bench WaveForm provided by ISE, and the test and error analysis of the system are also done.