The .8 Mm Lfmcw The Short-range Detection System Design

This dissertation is mainly on the design and realization of eight millmeter linear frequency modulation continuous wave (LFMCW) close detection system. The operating principle of the LFMCW detection system is introduced. The model of different frequency signal and error of distance measurement of symmetric triangular wave LFMCW detection system are analysed. Specific indexes and implementation of 8mm LFMCW close detection system are put forward.According to the indexes of system, antenna and circulator device parts of the detection system are chosen; modulated signal generator of triangular wave is made up with 8038 as the core chip; The VCO of eight millmeter is designed in the form of rectangular waveguide cavity,and the VCO is packaged and debugged. The bandwidth of electrical modulation is up to 100MHz and the nonlinearity is lower than 2%. A single mixer is assembled. A circuit, which is used to preprocess weak different frequency signal, is designed, including low noise amplifier berkeley packet filter,intermediate-frequency amplifier. A passive BPF with the structure of LC is designed, making the use of ADS.The hardware and software of digital signal processing system are completed with F2812, which is the core processing chip in the system. Schematic diagram and PCB figure of digital signal processing system are presented; On the basis of the requirement of detection system, software gives the flow of digital signal processing. Different frequency signal is gathered, checked, disposed with FFT. Through the analysis about the gathered signal of different frequency signal using ZFFT and the refined spectrum algorithm is given. The distance detection accuracy of miniature distance detection system is improved.Finally, the 8 mm LFMCW close detection system is tested, and the result of distance detection meets demand.