Research On Autocorrelation Function Estimation And Anomalous Spectrum Cancellation In Incoherent Scatter Radar

With the advancement of science and technology,the influence of the ionosphere on communication,navigation,imaging and other activities has attracted more and more attention.Therefore,ionosphere measurement is important for the scientific research and radio propagation application.Incoherent scatter radar is the most powerful tool for ionosphere measurement on the ground due to its wide detection range,high time and spatial resolution.From the perspective of signal processing,the study of the ionosphere is based on the study of the power spectrum of the echo signal of the incoherent scatter radar.In this paper,the simplified incoherent scatter spectrum and autocorrelation function model are derived,and the measured data of QJISR(Qujing Incoherent Scatter Radar)is used to improve the balance of autocorrelation function.At the same time,the incoherent scattering anomaly spectrum caused by the existence of space debris is cancelled.First,the basis of incoherent scatter radar detection is described.The ionosphere is a typical soft target and the detection of this type of target is different from the ordinary target.The scattered echo signals of different heights of the ionosphere are mixed and there is blurring,so the signal processing of the soft target is needed.The signal processing flow of incoherent scatter radar based on alternating code is introduced.The various ambiguity functions of the process are deduced and simulated,the lag profile matrix is introduced in detail,the autocorrelation function and power spectrum calculation process are analyzed.Second,the estimation of ionospheric incoherent scatter spectrum and autocorrelation function are studied.The classical incoherent scattering spectral model formula is more complex and can not inversely introduce the autocorrelation function.Based on this,the simplified incoherent scattering spectrum and autocorrelation function are re-derived.In order to improve the balance of autocorrelation function and the inversion accuracy of the ionospheric parameters,a method based on data fitting is proposed to estimate the autocorrelation at zero-lag.To improve the real-time performance of the algorithm and reduce the computational complexity in the subsequent processing,a more concise polynomial fitting model is used to approach the damping fitting model.Finally,research on the cancellation method of incoherent scattering anomaly spectrum.Incoherent scatter radar can not only detect the ionosphere,but also detect space debris at the same time.Therefore,space debris information may exist in the echo data of the incoherent scatter radar.In terms of the ionospheric incoherent scatter spectrum,the space debris scatter spectrum is called as anomalous spectrum.The anomaly spectrum is cancelled from three aspects:(1)the sorting statistical filtering algorithm is used to discriminate whether the anomalous spectrum caused by the space debris exists;(2)if it exists,the matching function method will be used to estimate the parameter information of the space debris;(3)the estimated space debris range information is used to cancel the anomalous spectrum.