Research On Method Of Dual-satellites Passive Location System Based On TDOA And FDOA

Positioning station does not transmit electromagnetic signals to the target,passively receiving the signal of the target and using the cooperative andnon-cooperative signals for precise positioning of the target, which is called passivelocation. Passive positioning technology occupies an important position due to itsgood concealment in modern electronic warfare. Dual-satellite passive locationsystem based on two satellites as a platform for passive positioning, it has theadvantages of few platforms needed, fewer channels, short positioning time and highprecision positioning et al. compared with the other passive positioning technology,and has important application value in the modern war and aviation, aerospace anddeep-space exploration, which is the main direction of present development. and hasimportant application value in the modern war and aviation, aerospace and deep-spaceexploration, which is the main direction of present development. If passive detectionaccuracy of this system was improved ulteriorly, it would be propitious to increase theability of electronic warfare，early warning detection and deep-space reconnaissanceexploration.The present positioning accuracy of dual-satellite passive location system isabout10~20km, which is still relatively low, unable to meet the needs of some users.The analysis and correction of the positioning error is a new research hotspot currently,but scholars at home and abroad, mainly focus on the ways such as optimizationlocalization algorithm, improving the positioning system as well as improving thereceiving equipment to improve detection accuracy on the location of the radiationsource, there is no systematic research on distribution and correction methods ofpositioning error.The distribution of positioning error about dual-satellite passive location systemis systematically analyzed, and the correction of positioning error is researched. Amulti-epoch time difference location method is proposed in the blind area zone, whichcan effectively solve the difficult problem about positioning in the blind area zone.Differential technique in the satellite navigation system is applied to this system,position differential and pseudo-differential method of dual-satellite passive locationsystem based on Time Different of Arrival and Frequency Different of Arrival areproposed, in which positioning accuracy can achieve better than5km.This paper focuses on the error correction research of the dual-satellite passivelocation system, mainly on the following aspects of the research work: (1) Main error sources of dual-satellite passive location systemPositioning model and solving method of dual-satellite passive location systemare studied in this paper, the main error sources in the dual-satellite passive locationsystem are analyzed, mainly concerning with the error related with measurement，theprocess of the propagation path，satellite errors and other error sources. The effect ofthe various parts of the error on the positioning accuracy is analyzed，the error size ofTDOA error and FDOA error are estimated, and the problem of the system to besolved is also analyzed.(2) Characterization positioning error by using geographic coordinates andanalysis on the distribution of positioning error.In order to be convenient for studying the positioning error of the system,characterization positioning error by using the geographic coordinate system isresearched in this paper. The characteristics of the equal time difference curve andequal frequency difference curve distribution are studied, the distribution of TDOAposition error contours, FDOA positioning error contours and TDOA/FDOApositioning error contours are given. According to using TDOA/FDOA jointpositioning, there exists the best location area, the worst positioning regional andblind positioning to be analyzed. Through the research of visualization software,GDOP distribution is given. Also key factors that affect the positioning precision ofdual-satellite passive location system are analyzed, involving the distance size of thedual-satellite, error size of time difference error and frequency difference error.(3) Multi-epoch time difference location for the position of the blind area zoneThe area that can’t be positioned when positioning is known as blind area zone.On the basis of analysis of the reason that blind area zone producing, in order toreduce distribution of the blind area zone, multi-epoch time differencelocation method is proposed in this paper, which can effectively solve the difficultproblem about positioning in the blind area zone, and positioning accuracy is alsohigher.(4) Position differential method and pseudo-differential method of dual-satellitepassive location systemBecause there are some similarities between the positioning error of this systemand that of satellite navigation system, the position differential method andpseudo-differential method being used for correcting the positioning error of thissystem are proposed in this paper. The feasibility of using the position differential approach and pseudo-differential method for positioning error correction are analyzed.The principle of position differential method and pseudo-differential method indual-satellite passive location system are given. The simulation test and experimentalresults are carried out. Finally factors affecting pseudo-range differential aredemonstrated. The results showed that: using position differential method andpseudo-differential method can improve the positioning accuracy of the system, butthe positioning accuracy of pseudo-differential is generally superior to that of positiondifferential, which can be controlled within5km.Through analysis of dual-satellite passive location system error systematically,multi-epoch time difference location method for the position of the blind area zone isproposed. In order to improve detection accuracy for the location of the radiationsource, the position differential and pseudo-differential method in satellite navigationsystem are applied to error correction of dual-satellite passive location system. Theeffect of the error correction is verified by using the simulation test, and positioningerror can be increased from the current10~20km up to5km.