Research And Data Analysis Of Linear Frequency Modulated Continuous Wave Radar Signal Processing

With the rapid development of digital signal processing technology, linear frequency modulated continuous wave (LFMCW) radar has been extensively explored in military and civil fields. LFMCW radar has the characteristics of no blind area, simple structure and low emission power, which has a great advantage in the detection of the short-range target.In this thesis, the system structure of LFMCW radar is first analyzed, and then based on the derivation and analysis of the sawtooth wave and symmetrical triangular linear frequency modulation signals, we investigate the characteristics of the echo beat signals of different frequency modulation modes. According to the difference of the echo beat signals between the moving target and the stationary target in the frequency domain, the moving target indicator technology of LFMCW radar is further studied. At the same time, the coherent accumulation is carried out by multiple periodic signal to improve signal-to-noise ratio, Moreover, this thesis focuses on the study of the moving target detection that technology that utilizes Doppler dimension to distinguish different speed targets.In range dimension, the Fast Fourier Transform (FFT) is usually used for frequency domain analysis, whose complexity increases with the number of samples. Thus the FFT is inconvenient for the real-time processing due to the high complexity. Since the number of targets corresponds to that of sharp peaks in the frequency domain, the number of targets is usually limited such that the target frequency domain has the sparsity. As such, the Sparse Fourier Transform (SFT) is proposed to optimize the process of distance measurement, in order to reduce the complexity of the Fourier transform and accelerate the processing speed of the system. Based on the study of SFT theory, the effect of SFT reconstruction results under different parameters settings and the corresponding experimental results are given.Finally, we utilize the ZYNQ platform to simulates the transmitting and receiving processes of LFMCW radar, and introduce the function of each module of the underlying system. The real scene is chosen to perform the detection of moving targets, whose echo data are subsequently dealt with by mixing and low-pass processing. Furthermore, some key factors that affect the final detection performance are analyzed, which provides a favorable support for the engineering application of the LFMCW radar.In the processing of measured data, the optimization parts of the whole system based on the SFT are analyzed, and the underlying issues are studied to demonstrate the feasibility of the SFT.