Research On Methods Of Modulation Signal Recognition And Parameter Estimation Based On ST-RFT Algorithm

The feature-based modulation signal recognition technology suffers from low recognition rate under low SNR environment,especially under the recognition with large variation range in the signal parameters.In this dissertation,the Short-time Ramanujan Fourier transform(ST-RFT)was introduced into modulation signal recognition,and the application feasibility of the algorithm based on ST-RFT was discussed by investigated signal extracted features and analyzed the recognition effects of the modulation recognitons.Meanwhile,the parameter estimation of the micro-motion modulation signal has been wide concerned,however,the traditional micro-motion parameter estimation approaches possess the contradiction of the estimation accuracy and computation.In this dissertation,the ST-RFT was introduced into the micro-motion target parameter estimation,and the application feasibility of the algorithm was discussed by analyzed the estimation accuracy of micro-motion target parameter.The ST-RFT algorithm was introduced into the research of intra-pulse modulation signal recognition including MP,LFM,BPCP,2FCP and 4FCP signals.The research proves that the signal recognition accuracy of the method based on combination algorithm of ST-RFT and pseudo-Zernike moments can reach 90% in low SNR environment with large variation range in the signal carrier frequency,time-bandwidth product of LFM signal and hop size of FCP signal,which is better than one of the algorithms based on STFT and WVD combined with transfer learning.The recognition method based on the combination algorithm of ST-RFT and pseudo-Zernike moments is feasible to be applied to the recognition of radar intra-pulse modulation signals.The ST-RFT algorithm was introduced into the research of digital modulation signal recognition including CW,2ASK,CPSK,2FSK and 4FSK signals.The research indicates that when SNR=0dB,the average correct recognition rate of the recognition method based on the ST-RFT algorithm can reach 90%,which is increased by 10.4% compared with one based on spectrogram time-frequency analysis algorithm.Especially,the correct recognition rate of the proposed method can increased by 9% for 4FSK,compared with that of the method based on instantaneous amplitude and instantaneous frequency features.The effectiveness of the proposed method in low SNR are proved by simulation results.The ST-RFT algorithm was introduced into the research of the vibrational frequency estimation of the micro-motion target with vibration.The research proves that in the presence of noise,the method based on ST-RFT algorithm has the advantage of high estimation accuracy and less computation than SPWVD based method and the method based on WVD,new basis decomposition and Hough transform.