Gao, YangXiang, Yan2018-10-042018-10-042018-09-21Xiang, Y. (2018). Carrier Phase-Based Ionospheric Modeling and Augmentation in Uncombined Precise Point Positioning (UPPP) (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/33086http://hdl.handle.net/1880/108733Precise Point Positioning (PPP) is a stand-alone high-precision positioning technique employing carrier phase measurements and external augmentation or aiding products. PPP reduces labor and equipment costs in contrast to Real-Time Kinematic (RTK) which relies on base stations. However, PPP suffers from a long convergence time of 15 to 60 minutes to reach the centimetre level. This long initialization time restricts the applications of PPP. To address this problem, we make use of accurate and precise ionospheric corrections. This dissertation endeavors to improve the ionospheric observables, Differential Code Biases (DCBs), and Mapping Function (MF). We then leverage these to reduce the convergence time. To obtain more accurate ionospheric corrections, we retrieve ionospheric observables using PPP. The ionospheric observables from the more commonly-used carrier phase smoothed code method are adversely affected by levelling errors. PPP offers a preferable way to reduce the leveling errors and preserve the consistency of ionospheric corrections, beneficial for shortening the convergence time of PPP. We demonstrate that the ionospheric observables retrieved from three PPP models, Traditional Ionosphere-Free, University of Calgary (UofC), and Uncombined (UPPP), all agree in terms of DCBs. The differences of ionospheric observables are at centimetre level. With the improved ionospheric observables using PPP, the stability and internal accuracy of satellite and receiver DCBs are also enhanced. The Root Mean Square (RMS) of the satellite DCB estimates is improved from 0.1 nanoseconds to 0.07 nanoseconds, and the day-to-day stability is enhanced by 0.22 nanoseconds. Another factor affecting ionospheric corrections is the MF which is mostly based on the fixed height Single-Layer Model (SLM). To reduce the effects of the inhomogeneity of the ionosphere, an Ionospheric Varying Height (IVH) is proposed and examined. Results show the mapping errors are reduced by about 15% when the integral varying height is exploited. By applying the improved ionospheric corrections into UPPP, we achieve an accuracy of 0.4 metres for global constraints and 0.2 metres for the regional constraints at the first epoch. The convergence time for the simulated kinematic mode is reduced from 41 to 7.5 minutes in the east at one decimetre, from 14.5 to 4.0 minutes in the north at one decimetre, and from 11.0 to 6.5 minutes in the vertical at two decimetres at a 68% confidence level.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.GNSSPrecise Point Positioning (PPP)faster PPPionospheric observableleveling errorDifferential Code Biases (DCB)mapping functionuncombined PPP (UPPP)GeodesyEngineering--AerospaceEngineering--AutomotiveEngineering--Marine and OceanRoboticsGeotechnologydoctoral thesis10.11575/PRISM/33086