Research Of Digital Signal Processing Methord In LFMCW Radar Altimeter

With the capability of digital signal processor strengthed and high resolution of spectrum consummated, digital signal processing such as FFT has been widly used in FMCW radar altimeter to realize high resolution of height. For the frequecncy space of FFT, the practical height precision is the same order as the system inherent resolution in short range. In some cases, it can hardly satisfy practical needs.Firstly, this dissertation discusses how can the LFMCW radar measure height, and then analyses the spectrum of minus-frequency under point-target and cover-target circumstance. For convenience, DDS is used to simulate the minus-frequency signal, so in the dissertation, the development of DDS, how to use AD9854 and how to design ellipse filter are introduced.At last, the dissertation summarizes the conception and characteristic of A/D, and also introduces how to design interface circuits; and then based on the flow of the signal processing of LFMCW radar altimeter and practical requirement of a certain radar system, I use FPGA and DSP realize high resolution of height with FFT and Chirp_z algorithms, and confirm it with data; then the last section of the dissertation, how to realize DSP link by FPGA is introduced, and also analyse the feasibility and validate the function.