Research On Frequency Difference Of Arrival Localization Technology For Low And Medium Orbit Satellites

With the development and wide application of satellite technology,satellite positioning technology has become more and more important.Passive positioning technology has been widely used because it will not expose its own position and has long range of action.In particular,passive positioning technology using Doppler frequency is playing an increasingly important role in the civil and military fields because of its suitability for positioning in low and medium orbit satellite systems.Based on the introduction of multi-satellite frequency difference positioning and single-satellite Doppler frequency measurement positioning technology,this paper proposes a different orbit single satellite based on satellite position optimization for complex positioning scenarios with limited field of view and frequency drift considerations.Combined with the proposed positioning technology based on the second difference of the Doppler frequency to offset the frequency drift generated by the target source indicator,significantly reduce the positioning error,and achieve effective positioning in complex positioning scenarios.Firstly,the paper describes the positioning principle based on Doppler information based on the comprehensive geometric characteristics,establishes the FDOA positioning model according to the positioning principle,derives the positioning equation,introduces the common positioning algorithm,and proposes an improved grid search algorithm.This algorithm can improve the positioning speed while maintaining the same level of positioning accuracy.Secondly,this article introduces the single-satellite Doppler time-division frequency measurement positioning technology,introduces GDOP and derives GDOP formula,and analyzes the relationship between the positioning effect and various measurement errors.Then,for positioning scenarios with limited field of view,a time-division frequency measurement positioning technology based on different orbit single satellites is proposed.The positioning equation is derived,and the observation constellation position optimization model is constructed using GDOP.The comparative analysis from the aspects of positioning availability,positioning accuracy,observation position selection,proves that the positioning accuracy of this positioning technology can reach 100 meters in the field of view positioning scene by using low-orbit satellites for positioning.Finally,aiming at the problem of location error caused by frequency drift of the target source indicator,a localization technology based on the second difference of the Doppler frequency is proposed.According to the positioning equation,the frequency drift model of the target source indicator is established and the effectiveness of the technology is verified by simulation.The results show that in complex positioning scenarios where the field of view is limited and frequency drift is considered,the technology of combining the second difference of the Doppler frequency and different-orbit single-satellite time-division frequency measurement positioning technology can achieve an ideal positioning effect.