Research On Micro-Doppler Feature Extraction Technology Of Rotorcraft

Micro-Doppler signals refer to Doppler scattering echo is caused by the micro movement of target,and micro-Doppler feature indicates structure information.and movement information.Therefore,related parameters of micro-Doppler features can be used to radar automatic target recognition.In recent years,the research of micro-Doppler is widely investigated.In this paper,a rotor micro-echo model is constructed for rotorcraft,and the study on the extraction of micro-Doppler feature based on S-transform.The main work of this paper are as follows:(1)The echo models of the rotating blades and multi-rotor UAV are set up based on micro-Doppler theory.The echo signal characteristics of rotorcraft and multi-rotor UAV are analyzed through simulation.(2)A modified generalized S transform is proposed.The main idea is using the arc-tangent function to control the window length within a certain length range,and getting a adaptive adjustment of the window length with frequency.The control factor is introduced to improve the adaptability of the algorithm further and improve the performance of time-frequency analysis.The simulation results show that the modified generalized S transform has a good performance in micro-Doppler feature extraction.(3)Fast implementation of the modified generalized S transform is derived.Reduce the redundancy of the calculation by limiting the frequency range during the transformation,and further reduce the amount of computation by frequency doubling sampling.(4)A micro-Doppler feature extraction method based on synchrosqueezing and modified generalized S transform is proposed.The energy rearrangement along the frequency axis is carried out in the process of the modified generalized S transform.The time-frequency transform of the partial derivative of the window function is used to calculate the instantaneous frequency,which reduces the complexity of the algorithm.The simulation results show that the proposed algorithm can effectively solve the problem that the time-frequency resolution can't be reconciled in the S transform,and the effective energy aggregation can be achieved while increasing the time-frequency resolution.