Research Of OTH Passive Direction Finding

Owing to far detecting range, high transmission power and excellent anti-jamming characteristic, long-range surveillance radar is mostly used to searching and scouting maritime or air target, and comes under countries consieration.Literature writing is rarely obtained at high accuracy direction finding for long-range surveillance radar.This paper research the high accuracy direction finding of OTH passive for this radar. The radar signal sorting is the basis and prerequisite for direction finding.Therefor,it mainly studies the radar signal sorting algorithm and high accuracy direction finding which the radiation source target antenna scan and tracking algorithm.Firstly, on the basis of studying the typical passive radar signal processing, it sheds light on signal processing process of the system of OTH passive direction finding from four aspects which include side lobe suppression, digital channel, signal sorting and angle estimate.Secondly, it studies radar signal sorting algorithm.To aim at the defects in the application of radar signal sorting of k-means clustering algorithm,this paper puts forward an improved algorithm based on data field and grey relational analysis. The algorithm has a good effect for a part of single parameter overlap or multiple parameters not overlap at the same time.The paper also discusses the CDIF,SDIF,PRI transform and modified PRI transform algorithm.Layer histogram algorithm is proposed and simulated to solve the problem of CDIF computation and SDIF underutilizing information.With the problem of complex signal sorting,it proposes a comprehensive sorting algorithm and shows the flow chart.Thirdly, the high accuracy direction finding which the radiation source target antenna scan and angle tacking algorithm.It formulates passive radar search method and search parameter through discussing intercepting characteristics when the two sides antenna scan.Direction finding model is established and the principle is explained.The paper studies the effect of radiation antenna scan on direction finding,noting the inapplicability of sample average and window function weighted average algorithm.It proposes an algorithm based on cycle amplitude weighted average and sliding smooth filtering accuracy direction-finding algorithm during the cycle and discusses the selection of sliding cycles.In view of the problem of passive angle tracking,model was established and kalman filtering is applied to passive angle tracking and filtering initial value selection is discussed.Finally, the paper studies the components of direction finding system,with the flow chart, and a comprehensive verification is done with measured data.