Abstract
Technique PPP–RTK combines the advantages of both the Precise Point Positioning (PPP) and the Real-Time Kinematic (RTK) positioning. With the emergence of multi-frequency Global Navigation Satellite System (GNSS) observations, it is preferable to formulate PPP–RTK functional models based on original (undifferenced and uncombined) observations. While there exist many variants of the undifferenced and uncombined PPP–RTK models, a unified theoretical framework needs developing to link these variants. In this contribution, we formulate a class of undifferenced and uncombined PPP–RTK functional models in a systematic way and cast them in a unified framework. This framework classifies the models into a code-plus-phase category and a phase-only category. Each category covers a variety of measurement scenarios on the network side, ranging from small-, medium- to large-scale networks. For each scenario, special care has been taken of the distinct ionospheric constraints and the difference between Code Division Multiple Access (CDMA) and Frequency Division Multiple Access (FDMA) signals. The key to systematically formulating these models lies in how to deal with the rank deficiency problems encountered. We opt for the Singularity-basis (S-basis) theory, giving rise to the full-rank observation equations in which the estimable parameters turn out to be the functions of original parameters and those selected as the S-basis. In the sequel, it becomes straightforward to derive for each scenario the user model as it, more or less, amounts to the single-receiver network model. Benefiting from the presented theoretical framework, the relationships and differences between various undifferenced and uncombined PPP–RTK models become clear, which can lead to the better use of these models in a specific situation.
Highlights
Global Navigation Satellite Systems (GNSSs) have long been providing high-precision positioning services with two classical techniques: Precise Point Positioning (PPP) and Real-Time Kinematic (RTK) positioning (Leick et al, 2015; Teunissen & Montenbruck, 2017)
PPP– RTK is more flexible than RTK since it inherits the State Space Representation (SSR) from PPP instead of the Observable Space Representation (OSR) adopted by RTK
Combining different SSR corrections estimated on the PPP–RTK network side produces various services: using satellite clock and orbit corrections makes PPP–RTK compatible with PPP (Gao & Shen, 2002; Liu et al, 2017); adding satellite phase bias correction allows for PPP–AR (Geng et al, 2012; Zhang et al, 2019); and further including atmospheric corrections achieves rapid, high-precision PPP–RTK positioning (Li & Ge, 2011; Zha et al, 2021)
Summary
Global Navigation Satellite Systems (GNSSs) have long been providing high-precision positioning services with two classical techniques: Precise Point Positioning (PPP) and Real-Time Kinematic (RTK) positioning (Leick et al, 2015; Teunissen & Montenbruck, 2017). − μjlrs + δrs,j − δ,sj + sj zrs,j where the rank deficiency between receiver and satellite clock errors is eliminated. This section clarifies these rank deficiencies and forms the ionosphere-weighted models for both CDMA and FDMA systems.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
