5 Mm Target Detection And Analysis Of Linear Frequency Modulation System

The millimeter wave in the non-atmospheric window is absorbed and scattered intensively when it is transmits in the atmosphere. Because of this, its transmission distance is very short. Due to the good Confidentiality, Highly Concealment of the millimeter-wave in the non-atmospheric window, satellite communications, near-field communications and a short-range radar are difficult to detected and jammed. Linear frequency modulation continuous wave (LFMCW)has special advantages of low transmit power small probability of intercept and no fuzzy distance highly range resolution.5mm LFMCW radar integrates the advantages of millimeter radar and linear frequency modulated radar, thus it has broader application prospects.Theoretically, LFMCW has highly ranging accuracy and range resolution. but increasing the sweep bandwidth is difficult to achieve. In addition, non-linear of the FM will cause the increase of the spectral side lobe thus inundate the target, impairing the ranging accuracy. In the project, the stability of the VCO’s frequency is not fine, linearity is also not ideal. This article mainly from the perspective of the ranging accuracy of spectral estimation.The paper points that triangle linear frequency modulation ranging principle in the time domain and frequency domain. Besides, it discusses the relationship between difference frequency signal and distance of target echo signal and transmitting signal. There is a linear relationship between the frequency and the target signal distance. Therefore, to obtain the target distance information based on the spectrum analysis for differential frequency signal to FM system. Since the traditional autocorrelation spectrum analysis of the signal is windowed, the equivalent of true autocorrelation function with the delay window. This paper uses the improved auto-correlation method of difference frequency signal spectrum estimation, reducing the effect of delay window, to improve the spectral resolution.The paper uses DSP chip to realization millimeter wave linear frequency modulation detection system signal processing. The TMS320VC5509A chip of TI company meets the design requirements of the system,5509A as the core processing chip and peripheral chip to accomplish the signal processing part. Use Prote199SE for circuit board design and layout, and through the CCS platform hardware test. Using C language to complete the signal processing software algorithm, comprehensive testing and hardware on CCS. The results show that the signal processing system accord with the requirement of millimeter wave frequency modulated system on the function, experimental tests have been the target distance and meet the actual requirement.