Precise Point Positioning Integer Ambiguity Resolution with Decoupled Clocks
Creators: name: Shi, Junbo
Publisher: name: Graduate Studies
Year: 2012
Subjects: subject: Geodesy
subject: GPS
subject: Precise Point Positioning
subject: Integer ambiguity resolution
subject: Decoupled clocks

description: Precise Point Positioning (PPP) integer ambiguity resolution has been a challenging topic during the past five years. So far, three PPP integer ambiguity resolution methods – the singledifference between satellites method, the decoupled clock model and the integer phase clock model – have been developed. By using integer ambiguity resolution in PPP, cm-level ambiguity-resolved positioning accuracy can be obtained with hourly observations. However, some limitations still exist. First, no comprehensive comparison is provided to derive the equivalence of three existing PPP integer ambiguity resolution methods. Second, no user confirmation is made to assess the PPP integer ambiguity resolution method and corresponding products. Third, specific integer ambiguity searching and validation methods in PPP have not yet been developed. Fourth, although the ambiguity-resolved horizontal positioning accuracy has been found significantly improved, the height coordinate improvement is always less significant than its horizontal counterparts. How the ambiguity-resolved height solution can be improved requires further investigation. Fifth, no efforts have been made to assess the ambiguity-resolved troposphere solution, which could potentially benefit some meteorological applications. This thesis has derived the equivalence of three PPP integer ambiguity resolution methods. A comprehensive comparison among the three has been provided with a focus on the nature of the clock, the bias and the ambiguity terms in each method. The method equivalence is demonstrated in three aspects: the integer property recovery, the system redundancy and the correction broadcasting burden. iii The user implementation procedure of the PPP integer ambiguity resolution method with decoupled clocks has been derived. Following the assessment of satellite decoupled clock products from NRCan, some user implementation details not clarified in existing publications, such as the clock/ambiguity datum, the unknown parameters and the system redundancy, are discussed. Furthermore, a set of partial ambiguity resolution and validation methods have been developed for PPP. The first user confirmation of the PPP integer ambiguity resolution method and corresponding products have been conducted with the decoupled clock model and satellite decoupled clock products provided by NRCan. First, the performance evaluation of ambiguity fixing time and positioning accuracy has been conducted. Second, the limiting factor to the insignificant height improvement is identified and a troposphere constraint method has been proposed. Third, the ambiguity-resolved troposphere solution has also been evaluated for its potential benefits to meteorological applications. Some future works are provided in the end to consider the user confirmation using nonpermanent stations under various observation environments, the user performance maximization and the extension of PPP integer ambiguity resolution with decoupled clocks into real-time applications.