Research On Doppler Shift Estimation In MSK-LFM Radar Communication Integration

Research on Doppler shift estimation of radar communication integration scheme with the development and of radar and communication technology,radar communication integration scheme can break the isolation of two systems and make them work together efficiently.In the aspect of radar communication integrated signal,MSK-LFM signal has the advantages of continuous phase and light spectrum expansion beyond the bandwidth,which has been widely discussed and studied in recent years.However,the coherent demodulation performance of MSK-LFM signal is seriously affected by Doppler frequency shift,and the traditional Doppler frequency shift estimation algorithm cannot be applied to the integrated signal.Therefore,this paper proposes two Doppler frequency shift estimation algorithms for MSK-LFM signal,which are applied to different scenes.The main work is as follows:1.Aiming at the problem that the traditional Fitz algorithm cannot be applied to the linear variation of carrier frequency,an iterative Fitz algorithm is proposed.The improved algorithm can estimate the Doppler frequency shift of MSK-LFM signal by linear iteration based on Fitz algorithm.Simulation results show that the performance of the algorithm is good in the environment of noise,and the mean square error of Doppler shift estimation is about this order of magnitude is10^-4.2.Although the iterative Fitz algorithm can estimate the Doppler frequency shift of MSK-LFM signal,the error between the estimated value and the actual value is too high when the Doppler frequency shift is large.In order to solve this problem,according to the carrier form of MSK-LFM signal,the sparse recovery algorithm is adopted,and the fast atomic parameter group selection strategy proposed in this paper is used to estimate the frequency modulation rate of the received signal,and the estimated value of Doppler frequency shift is calculated by the relationship between the estimated value of frequency modulation rate and Doppler frequency shift factor.The simulation results show that the performance of this method is good.When the signal-to-noise ratio is 3 d B,the mean square error of Doppler shift factor estimation is about this order of magnitude is10^-4,and in the low signal-to-noise ratio environment,the mean square error of Doppler shift estimation is about this order of magnitude is10^-3,the performance of Doppler shift estimation in high SNR environment is similar to that of iterative Fitz algorithm.