Rejection And Detection Of Multipath Signals For Distributed MIMO Sky-wave Radar

The demand for ultra-long-range targets and stealth target detection has made the sky-wave radar more and more popular.High-frequency sky-wave radar uses the reflection of the ionosphere to achieve over-the-horizon detection of the target.However,the stratification characteristics of the ionosphere often cause multiple reflection paths between the radar and the target,and multipath for high-frequency sky-wave radar.The multi-input and multi-output MIMO radar can effectively alleviate the impact of such interference,and has been applied in sky-wave radar.Distributed MIMO radar has better anti-interference characteristics due to the sufficient separation of its transmit and receive antenna array space.In this paper,the following work is done on the rejection and detection of multipath signals of distributed MIMO sky-wave radar:Firstly,the sky-wave OTHR radar ionospheric model is briefly described,and the MIMO sky-wave radar array signal model is introduced.Then the spatial smoothing MUSIC algorithm commonly used in DOA estimation is studied.Secondly,for multipath interference with unpredictable path,a multipath signal interference suppression method based on DBN and feature projection preprocessing for MIMO high frequency sky-wave radar is presented.The DBN model is used to identify whether there is multipath interference,and the interference DOA is estimated.Then the multi-path interference is suppressed by the feature projection preprocessing method.Finally,the suppression result of the method for multipath interference is obtained.Finally,for multipath signals with predictable paths,the multi-path signal detection algorithm for distributed MIMO high-frequency sky-wave radar is studied.Firstly,the GLRT is derived by using the maximum likelihood estimation method for unknown parameters.,Wald detector and Rao detector,and improved Rao detection algorithm.Then the Expected Likelihood(EL)detection algorithm is given,and under the condition of low SNR,an improved EL detection algorithm is given.The detection effect is better and the target detection ability can be improved.Then based on the improved EL detection algorithm,the method of multi-path echo detection is studied.Finally,the distributed MIMO sky-wave radar multi-path signal detection method is given.