Research And FPGA Implementation Of Parameter Estimation Algorithm For Moving Targets In LFMCW Radar

Comparing with other radar systems,the LFMCW radar system has high resolution under the same bandwidth and high sensitivity under transmit power,without range blind area etc.It is widely used in ship navigation,such as monitoring ports,guiding to avoid obstacle in collision and foggy day and night traveling.Based on the continuous wave radar navigation system,research on the characteristics of LFMCW radar beat signal and target recognition algorithm are studied,which focus on the influence of sea clutter,distancevelocity coupling and fence effect on the estimation of target information.The target detection algorithm and frequency correction algorithm based on spectral peak search are designed.At the same time,the parameter information of the target is calculated through precise estimation of frequency points.The main work of this thesis is summarized as follow.Firstly,the mathematical modeling of the LFMCW radar beat signal with sea clutter and the suppression of the sea clutter.The characteristics of the beat signal of LFMCW radar are analyzed,and the factors affecting the accuracy of target parameters are studied.Based on the pulse wave radar system,a sea clutter model is established based on the LFMCW system radar.The sea clutter suppression algorithm based on wavelet threshold is adopted to reconstruct the detail layer with the most significant echo and the largest SNR which completes the suppression of sea clutter signal.Secondly,the effective frequency point of the target spectrum peak position is found out and revised.Suppression of range velocity coupling problem is suppressed by twodimensional FFT algorithm to obtain the rough information of the target parameters and find out the frequency points corresponding to the location of the target spectral peak by the spectral peak search algorithm.Meanwhile,in order to get the accurate information of the target parameters,this paper proposes an improved Quinn algorithm to correct the target frequency points and calculates the target information parameters by using the ranging velocity formula.Finally,based on the LFMCW radar hardware platform,the LFMCW radar transmitter is tested,and the FPGA controls the DDS chip to generate a sweep signal with the upper and lower limits of 1017.5 MHz and 982.5 MHz.Respectively,the radar signal is sent out by the radar antenna after amplification,frequency doubling and filtering.Then the AD chip is used to sample the beat signal which is received by the radar antenna.At last,the LFMCW radar signal is processed with the correlation algorithm,and the existing hardware platform is used to test it.LFMCW radar actual calculation errors in the testing result is less than the theoretical value,the range error is less than 1m and velocity error is less than 3m/s.