Starlink Tabanlı Radyo Konumlama Sisteminin Kavramsal Tasarımı

Abstract

Studies are being carried out to use communication satellites in Low Earth Orbit (LEO) as opportunity signals for positioning in addition to the traditional use of GNSS systems. The fact that LEO satellites are closer to the earth than GNSS satellites, provide less loss in signals and jamming techniques have improved in recent years, making it possible to use LEO-based positioning systems in regions where GNSS systems cannot be used. The downlink signals broadcasted for internet communication from Starlink satellites, along with the tone signals within the guard band, have made it possible to use Starlink satellites for positioning purposes as the Starlink satellites increased their numbers in LEO. In this thesis, it is assumed that a static receiver tracks the Starlink OFDM and tone signals, aiming to estimate the receiver's position using Doppler measurements. An estimator architecture based on the least squares method is proposed for position estimation. In positioning methods using Doppler measurements, factors such as satellite and receiver clock drift and drift rate, noise errors, orbital errors and measurement time error effect satellite position and velocity and Doppler measurements. Also parameters of the positioning method that Doppler frequency and the number of measurements within the method significantly effect the estimation performance. To observe the effects of these parameters and errors on estimation performance, positioning studies have been carried out in a simulation environment.