Strong Interference Othr Target Detection And Signal Recovery

Over-the-horizon radar (OTHR) usually works in HF band which detects targets at a long distance by detecting the back reflection echo from the ionosphere.OTHR has the features of long-distance detection,large areas surveillance,anti-stealth capacity,and so on.In military, it is mainly used to make early warning of ballistic missile,low air bomber,cruise missile and attack fleet at sea.At the HF band,Bragg scattering occurs when Hertzian waves refract ocean surface-wave.Therefore,OTHR is widely used for remotely sensing of ocean surface-waves in civil application.However,since the complex target characteristic and propagation environment of HF band,OTHR needs a lot of effective signal process methods to assure its advantages of long-distance detection,anti-stealth and early warning ability.This dissertation studies some signal processing methods of OTHR for target detection and transient interference rejection.Firstly, this dissertation introduces the theory of range-Doppler information detection of linear frequency modulated continuous wave (LFMCW) signal.In order to get the azimuth information ,the direction of arrival (DOA) estimation method of OTHR is analyzed.Secondly, in order to detect the transient interference existed in OTHR echo,the threshold method and wavelet method are studied.The method to reject the interference based on linear prediction is developed.For each method ,some computer simulations are discussed and some conclusions are drawn.Finally, the signal processing of transient interference rejection and doppler information detection in OTHR are applied in the ADSP-21160 DSP processor ,and the result is shown.