A modified phase clock/bias model to improve PPP ambiguity resolution at Wuhan University

Geng, Jianghui; Chen, Xingyu; Pan, Yuanxin; Zhao, Qile

doi:10.1007/s00190-019-01301-6

Cited by 93 publications

(38 citation statements)

References 26 publications

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“…At each epoch, we could observe on average eight GPS satellites and seven GLONASS satellites. Another 40 stations were used to calculate precise satellite clock corrections and 60 more used for phase bias and code‐phase bias computations to enable PPP ambiguity resolution (PPP‐AR) for both GPS and GLONASS ( cf ., Geng, Chen, Pan, & Zhao, 2019). A cut‐off angle of 10° above the horizon was set for usable GNSS observations which were later weighted according to an elevation‐dependent strategy.…”

Section: Gnss Data Processingmentioning

confidence: 99%

Comparing Non‐Tidal Ocean Loading Around the Southern North Sea With Subdaily GPS/GLONASS Data

et al. 2021

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Observing subdaily surface deformations is important to the interpretation of rapidly developing transient events. However, it is not known whether Global Navigation Satellite System (GNSS) is able to identify millimeter-level transient displacements over various subdaily timescales. We studied non-tidal ocean loading (NTOL) using 18 GNSS stations along the southern North Sea for November-December 2013 and compared 3-h GPS/GLONASS displacements with NTOL predictions. It was found that they overall agreed well with a mean correlation coefficient of 0.6 and their vertical differences had an RMS of 5.7 mm, but a 10-mm subsidence prediction for December 5th could only be marginally detected. Hence, the spatial coherence among the loading signatures at the 18 stations was harnessed to improve subdaily GNSS, and then the predicted displacements of 5-10-mm over the subdaily timescales could be discriminated successfully. We envision that adding Galileo/BeiDou signals to GPS/GLONASS can further improve the resolution of subdaily GNSS, which can also enhance the spatial coherence of transient signals captured by regional GNSS stations. GENG ET AL.

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Section: Gnss Data Processingmentioning

confidence: 99%

Comparing Non‐Tidal Ocean Loading Around the Southern North Sea With Subdaily GPS/GLONASS Data

et al. 2021

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“…Teunissen and Khodabandeh (2015) theoretically proved that the f rac(Θ) operator here is not rigorous in computing phase biases and the resulting positions would be biased. Geng et al (2012) and Geng et al (2019) then suggested that the ultimate high-precision FCB products should be computed by resolving ambiguities of the network in advance.…”

Section: Estimation Of Fractional-cycle Biases (Fcbs)mentioning

confidence: 99%

Speeding up PPP ambiguity resolution using triple-frequency GPS/BeiDou/Galileo/QZSS data

Geng

Guo

Meng

et al. 2020

J Geod

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Precise point positioning (PPP) has been suffering from slow convergences to ambiguity-fixed solutions. It is expected that this situation can be relieved or even resolved using triple-frequency GNSS data. We therefore attempt an approach where uncombined triple-frequency GPS/BeiDou/Galileo/QZSS (Quasizenith satellite system) data are injected into PPP, whereas their raw ambiguities are mapped into the extra-wide-lane, wide-lane and narrow-lane combinations for integer-cycle resolution at a single station (i.e., PPP-AR). Once both extra-widelane and wide-lane ambiguities are fixed to integers, the resulting unambiguous (extra-)wide-lane carrier-phase can usually outweigh the raw pseudorange to improve the convergence of positions and narrow-lane ambiguities. We used 31 days of triple-frequency multi-GNSS data from 76 stations over the Asia-Oceania regions and divided them into hourly pieces for real-time PPP-AR. We found that the positioning accuracy for the first ten minutes of epochs could be improved by about 50% from 0.23, 0.18 and 0.43 m to 0.12, 0.08 and 0.27 m for the east, north and up components, respectively, once wide-lane ambiguity fixing was achieved for triple-frequency PPP. Consequently, 48% of PPP solutions could be initialized successfully with narrow-lane ambiguities resolved within 2 minutes, in contrast to only 26% for dual-frequency PPP. On average, 6 minutes of epochs were required to achieve triple-frequency PPP-AR whereas 9 minutes for its dual-frequency counterpart. Of particular note, the more satellites contribute to triple-frequency PPP-AR, the faster the initializations will be; as a typical example, the mean initialization time declined to 3 minutes in case of 20-21 satellites. We therefore envision

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“…In the past decade, algorithms for PPP with ambiguity resolution (PPP‐AR) have matured from experimental to operational solutions (Geng et al., 2019; Loyer et al., 2012; Schaer et al., 2018; Strasser et al., 2019). Ambiguity resolution offers significant benefits for users by transforming ambiguous carrier‐phase observations into precise ranges.…”

Section: Introductionmentioning

confidence: 99%

Enabling ambiguity resolution in CSRS‐PPP

et al. 2021

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Precise point positioning (PPP) uses precise satellite orbits, clock corrections and biases derived from a global network of reference stations to enable accurate positioning worldwide. Natural Resources Canada's Canadian Spatial Reference System (CSRS) PPP is a free Web service offering automated PPP processing. A critical factor limiting the adoption of PPP in many applications is the convergence time needed to reach centimeter‐level accuracies. To address this issue, CSRS‐PPP now implements PPP with ambiguity resolution (PPP‐AR). This feature required the development of new algorithms, such as sequential normal stacking for least‐squares filtering/smoothing, and the weighted integer decision concept for ambiguity validation. New satellite product lines (ultra‐rapid, rapid, final) also have been deployed to enable PPP‐AR processing with various latencies. This analysis demonstrates that sub‐centimeter horizontal accuracies can be obtained in less than one hour for both static and kinematic modes. Using product lines with longer latencies is beneficial, although improvements are typically within the reported uncertainties.

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A modified phase clock/bias model to improve PPP ambiguity resolution at Wuhan University

Cited by 93 publications

References 26 publications

Comparing Non‐Tidal Ocean Loading Around the Southern North Sea With Subdaily GPS/GLONASS Data

Comparing Non‐Tidal Ocean Loading Around the Southern North Sea With Subdaily GPS/GLONASS Data

Speeding up PPP ambiguity resolution using triple-frequency GPS/BeiDou/Galileo/QZSS data

Enabling ambiguity resolution in CSRS‐PPP

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