Undifferenced GPS Ambiguity Resolution Using the Decoupled Clock Model and Ambiguity Datum Fixing

Collins, Paul; Bisnath, Sunil; Lahaye, F.; Héroux, Pierre

doi:10.1002/j.2161-4296.2010.tb01772.x

Cited by 254 publications

(162 citation statements)

References 19 publications

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“…For all of the PPP daily solutions, a decoupled receiver clock is applied for both GPS and GLO (Collins et al, 2010), and the ionospherically-free observable is used, with no second order ionospheric bias corrections applied. The ionospherically-free combinations for the code and phase observables follow (Dach et al, 2007a):…”

Section: Ppp Daily Solutions Methodologymentioning

confidence: 99%

An assessment of static precise point positioning using GPS only, GLONASS only, and GPS plus GLONASS

et al. 2016

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Abstract:The aim of this paper is to look into the achievable repeatability and accuracy from Precise Point Positioning (PPP) daily solutions when using GPS only (PPP GPS), GLONASS only (PPP GLO), and GPS plus GLONASS (PPP GPS+GLO) for static positioning. As part of the assessment, a comparison with global double difference (DD) GPS daily solutions is presented. It is shown, therefore, that all of the PPP daily solutions can achieve millimetric level repeatability, similar to the global DD GPS solutions. Furthermore, the mean of the biases between the PPP daily solutions and the global DD GPS daily solutions are constellation type dependent, while an improvement is found in the vertical component for PPP GPS+GLO over PPP GLO, as the latter may be more affected by any imperfections in the models for GLONASS antenna phase centre variations. It is concluded that PPP GLO daily solutions have the ability to be used as independent solutions to PPP GPS daily solutions for static positioning, and as an alternative to PPP GPS+GLO or global DD GPS daily solutions.

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Section: Ppp Daily Solutions Methodologymentioning

confidence: 99%

An assessment of static precise point positioning using GPS only, GLONASS only, and GPS plus GLONASS

et al. 2016

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“…Ambiguity resolution in PPP (PPP-AR) requires the equipment delays within the GPS measurements to be mitigated, which would allow for resolution of the integer nature of the carrier-phase measurements Collins 2008;Mervart et al 2008;Ge et al 2008;Teunissen et al 2010;Bertiger et al 2010;Geng et al 2012;Lannes and Prieur 2013). Resolution of these ambiguities convert the carrier-phases into precise pseudorange measurements, with measurement noise at the centimetreto-millimetre level compared to the metre-to-decimetrelevel of the direct pseudoranges (Collins et al 2010). If the ambiguities could be isolated and estimated as integers, then there would be more information that could be exploited to accelerate convergence to give cm-level horizontal accuracy within an hour of data collection.…”

Section: Introductionmentioning

confidence: 99%

An assessment of the interoperability of PPP-AR network products

Seepersad

Bisnath

2017

J. Glob. Position. Syst.

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Integer ambiguity resolution of carrier-phase measurements from a single receiver can be implemented by applying additional satellite corrections (products) to mitigate unmodelled satellite equipment delays. Interoperability of different PPP-AR products would allow the PPP user to transform independently generated PPP-AR products to obtain multiple fixed solutions of comparable precision and accuracy with limited changes required to user PPP measurement processing software. The ability to provide multiple solutions would increase the reliability of the solution for, e.g., real-time processing; if there were an outage in the generation of one set of PPP-AR products, the user could instantly switch streams to a different provider. There are currently three main public providers of real-time products that enable PPP-AR. These include School of Geodesy and Geomatics at Wuhan University (SGG-WHU), Natural Resources Canada (NRCan) and Centre National d'Etudes Spatiales (CNES). The presented research examines the PPP-AR products generated from the FCB (Fractional Cycle Bias) model and IRC (Integer Recovery Clock) model that have been transformed into the DC (Decoupled Clock) format and applied within the PPP user solution. Interoperability of the different PPP-AR products is a challenging task due to the public availability of different quality of products, limited literature documenting the conventions adopted within the network solution of the providers and unclear definitions of the corrections. The novelty of the research is in the analysis of using the transformed products. The convergence time (time to first fix and time to a pre-defined performance level), position precision (repeatability), position accuracy and solution outliers are examined. Equivalent performance was noted utilizing the different methods. Of the four solutions, FCB products had the highest accuracy. This is attributed to the products being generated using final IGS orbit and clock products. To confirm this, FCBs generated using GRG orbit and clock products were also examined and comparable performance was observed between the FCBs and IRC (GRG) products. The least accurate solution was obtained using the IRC (CNT) products, which was due to the products being archived real time products.

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“…These errors can be categorized into three classes: satellite related errors, signal propagation related errors, and receiver/antenna configuration errors (El-Rabbany, 2006). A number of comprehensive studies have been published on the accuracy and convergence time of un-differenced combined GPS PPP model (see for example : Zumberge et al, 1997;Kouba and Héroux, 2001;Colombo et al, 2004;Ge at el., 2008;Collins at al., 2010;Afifi and El-Rabbany, 2015;Afifi and ElRabbany, 2016;Abd Rabbou and El-Rabbany, 2015;Tegedor et al, 2015;Li, et al, 2013;El-Mowafy, et al, 2016;Melgard et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Research Article. Improved Dual Frequency PPP Model Using GPS and BeiDou Observations

Afifi¹,

El-Rabbany²

2017

Journal of Geodetic Science

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This paper introduces a new dual-frequency precise point positioning (PPP) model, which combines GPS and BeiDou observations. Combining GPS and BeiDou observations in a PPP model offers more visible satellites to the user, which is expected to enhance the satellite geometry and the overall PPP solution in comparison with GPSonly PPP solution. However, combining different GNSS constellations introduces additional biases, which require rigorous modelling, including GNSS time offset and hardware delays. In this research, ionosphere-free linear combination PPP model is developed. The additional biases, which result from combining the GPS and BeiDou observables, are lumped into a new unknown parameter identified as the inter-system bias. Natural Resources Canada's GPSPace PPP software is modified to enable a combined GPS/BeiDou PPP solution and to handle the newly introduced biases. A total of four data sets at four IGS stations are processed to verify the developed PPP model. Precise satellite orbit and clock products from the IGS-MGEX network are used to correct both of the GPS and BeiDou measurements. It is shown that a sub-decimeter positioning accuracy level and 25% reduction in the solution convergence time can be achieved with combining GPS and BeiDou observables in a PPP model, in comparison with the GPS-only PPP solution.

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Undifferenced GPS Ambiguity Resolution Using the Decoupled Clock Model and Ambiguity Datum Fixing

Cited by 254 publications

References 19 publications

An assessment of static precise point positioning using GPS only, GLONASS only, and GPS plus GLONASS

An assessment of static precise point positioning using GPS only, GLONASS only, and GPS plus GLONASS

An assessment of the interoperability of PPP-AR network products

Research Article. Improved Dual Frequency PPP Model Using GPS and BeiDou Observations

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