| Summary: | 碩士 === 國防大學中正理工學院 === 軍事工程研究所 === 96 === With the satellite systems of modernized GPS (MGPS) launched in 2005, the new C/A code of GPS satellites which have been modulated in L2 frequency band (L2C) have gradually been used in GPS navigation and positioning. The accuracy, availability, integrity, and reliability of L2C signals have been mainly increased and the qualities of observations certainly degrade the positioning errors.
This study of Precise Point Positioning (PPP) addresses issues related to combine MGPS with the products of precise ephemeris to form a novel technology of point positioning. The feature of PPP is the positioning process with dual-frequency pseudorange observations and the positioning accuracy can reach 1 to 3 meters.
The L2C observations of six-station collected from the international L2C network were used to test the algorithms of PPP. In this research, the algorithms of PPP are based on dual-frequency codes ionosphere-free (IF) linear combinations. The outcomes of testing shows that by adding the more L2C observations, the higher positioning accuracy. It can reach 25.14% in horizontal direction and 24.50% in vertical direction.
Keywords: Modernized GPS, Precise Point Positioning, Ionosphere-Free
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