Research On Signal Processing Of Incoherent Scatter Radar

With the development of modern technology,the influence of ionosphere on human activities become more and more serious,such as satellite navigation,wireless communication,broadcast,and space exploration.Therefore,detection of ionosphere becomes more and more important.With high temporal-spatial resolution and wide detection range,incoherent scatter radar is able to detect the weak echo signal from the ionosphere.Because of the specialty of ionosphere,incoherent scatter radar usually uses complicated signal coding and signal processing methods.In this paper,based on the construction and experiments of Qujing incoherent scatter radar,the signal processing algorithm is studied in detail.While a signal processing software is designed in this paper,too.Firstly,the detection principle of incoherent scattering radar is studied.The signal processing flow of incoherent scattering radar is introduced,and the theory of ambiguity function and the formation principle of lag profile matrix are studied.The relation between the two dimensional ambiguity function,the distance amplitude ambiguity function and the distance ambiguity function is derived.Meanwhile,the relation between the autocorrelation function of ionospheric plasma and the ambiguity function and the autocorrelation function of the scattered signal is derived.The method of calculating the autocorrelation function from the lag profile matrix and obtaining the power spectrum by the autocorrelation function is given.The traditional signal processing algorithms of traditional long pulse,modern long pulse,integer order alternating codes and fractional order alternating codes are introduced.And their advantages and disadvantages are analyzed.Moreover,aiming at the shortages of the traditional signal processing algorithms,a new post-detection filtering algorithm and spectral estimation algorithm are introduced.Combined with the experimental results,the new method is compared with the traditional algorithm.The finite impulse response filter is designed according to the window function,and the original box filter is replaced to improve the performance of the post-detection filter of incoherent scatter radar.Meanwhile,the auto regressive(AR)model and the minimum variance spectrum estimation method are introduced into the signal processing of incoherent scatter radar to improve the accuracy of spectral estimation.Finally,a signal processing software with the above algorithm is designed to improve the flexibility and reliability of the system.The functional requirements of the software are analyzed and the software is divided into four functional modules of the data configuration module,data display module,signal processing module and image display and operation module.The data configuration module is divided into the configuration selection module and configuration display module.Each module is designed and implemented.In order to improve the flexibility and scalability of the software algorithm,the mixed programming technology of MATLAB and VC++ is applied to the signal processing module.Finally,each module of the software is tested,and the reliability of the software is verified.