Towards PPP-RTK: Ambiguity resolution in real-time precise point positioning

Geng, Jianghui; Teferle, Felix Norman; Meng, Xiaolin; Dodson, Alan

doi:10.1016/j.asr.2010.03.030

Cited by 224 publications

(124 citation statements)

References 20 publications

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“…All available satellites over an elevation angle of 7° were used for wide-lane ambiguity resolution, whereas those over 15° for narrow-lane ambiguity resolution. For the clock determination and the FCB determination, we refer to Geng (2009) and Geng et al (2010). Note that communication delays were ignored in our simulated realtime study.…”

Section: Remarks On the Methods Implementationmentioning

confidence: 99%

“…Although such networks are normally not available for PPP, we can envision that if precise ionospheric delays can be derived from a sparse network at scales of several hundred kilometers using an ionospheric tomography technique (e.g. Hernández-Pajares et al 2000), a PPP-RTK service (Geng et al 2010) that can rapidly provide ambiguity-fixed solutions may potentially prevail against current RTK positioning services based on dense networks …”

Section: Conclusion and Perspectivementioning

confidence: 99%

“…Moreover, GPS satellite orbits are tightly constrained by dynamic force models, and thus the residual orbit errors should change smoothly in theory. On the other hand, for a re-convergence, the receiver position can be known to the centimeter-level accuracy from previous ambiguity-fixed solutions (Geng et al 2010). …”

Section: Precisely Predict Ionospheric Delaysmentioning

confidence: 99%

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Rapid re-convergences to ambiguity-fixed solutions in precise point positioning

Geng

Meng

Dodson

et al. 2010

J Geod

155

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Integer ambiguity resolution at a single station can be preformed if the fractional-cycle biases are separated from the ambiguity estimates in precise point positioning (PPP). Despite the improved positioning accuracy by such integer resolutions, the convergence to an ambiguity-fixed solution normally requires at least a few tens of minutes. More importantly, such convergences can repeatedly occur on the occasion of losses of tracking locks for many satellites if an open sky-view is not constantly available, consequently totally destroying the practicability of real-time PPP. In this study, in case of such re-convergences, we develop a method in which ionospheric delays are precisely predicted to significantly accelerate integer ambiguity resolutions. The effectiveness of this method consists in two aspects: First, wide-lane ambiguities can be rapidly resolved using the ionospherecorrected wide-lane measurements, instead of the noisy Melbourne-Wübbena combination measurements; second, narrow-lane ambiguity resolution can be accelerated under the tight constraints derived from the ionosphere-corrected unambiguous wide-lane measurements. In the tests at 90 static stations suffering from simulated total loss of tracking locks, 93.3% and 95.0% of reconvergences to wide-lane and narrow-lane ambiguity resolutions can be achieved within 5 s, respectively, even though the time latency for the predicted ionospheric delays is up to 180 s. In the tests at a mobile van moving in a GPS-adverse environment where satellite number significantly decreases and cycle slips frequently occur, only when the predicted ionospheric delays are applied can the rate of ambiguity-fixed epochs be dramatically improved from 7.7% to 93.6% of all epochs. Therefore, this method can potentially relieve the unrealistic requirement of a continuous open skyview by most PPP applications and improve the practicability of real-time PPP. Integer ambiguity resolution at a single station can be preformed if the fractional-cycle biases are separated from the ambiguity estimates in precise point positioning (PPP). Despite the improved positioning accuracy by such integer resolutions, the convergence to an ambiguity-fixed solution normally requires at least a few tens of minutes. More importantly, such convergences can repeatedly occur on the occasion of losses of tracking locks for many satellites if an open sky-view is not constantly available, consequently totally destroying the practicability of real-time PPP. In this study, in case of such re-convergences, we develop a method in which ionospheric delays are precisely predicted to significantly accelerate integer ambiguity resolutions. The effectiveness of this method consists in two aspects: First, wide-lane ambiguities can be rapidly resolved using the ionosphere-corrected wide-lane measurements, instead of the noisy Melbourne-Wübbena combination measurements; second, narrowlane ambiguity resolution can be accelerated under the tight constraints derived from the ionospherecorrected unambiguou...

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Section: Remarks On the Methods Implementationmentioning

confidence: 99%

Section: Conclusion and Perspectivementioning

confidence: 99%

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Rapid re-convergences to ambiguity-fixed solutions in precise point positioning

Geng

Meng

Dodson

et al. 2010

J Geod

155

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show abstract

“…This issue has recently been addressed by Geng et al (2010) through the FCB estimation method and Collins (2008) and Laurichesse et al (2011) through the Integer Recoverable Clock (IRC) method. To date these two methods are the main fixed ambiguity PPP approaches for the GPS-only scenarios.…”

Section: Introductionmentioning

confidence: 99%

GLONASS Aided GPS Ambiguity Fixed Precise Point Positioning

et al. 2013

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The Precise Point Positioning (PPP) concept enables centimetre-level positioning accuracy by employing one Global Navigation Satellite System (GNSS) receiver. The main advantage of PPP over conventional Real Time Kinematic (cRTK) methods is that a local reference network infrastructure is not required. Only a global reference network with approximately 50 stations is needed because reference GNSS data is required for generating precise error correction products for PPP. However, the current implementation of PPP is not suitable for some applications due to the long time period (i.e. convergence time of up to 60 minutes) required to obtain an accurate position solution. This paper presents a new method to reduce the time required for initial integer ambiguity resolution and to improve position accuracy. It is based on combining GPS and GLONASS measurements to calculate the float ambiguity positioning solution initially, followed by the resolution of GPS integer ambiguities.The results show that using the GPS/GLONASS float solution can, on average, reduce the time to initial GPS ambiguity resolution by approximately 5% compared to using the GPS float solution alone. In addition, average vertical and horizontal positioning errors at the initial ambiguity resolution epoch can be reduced by approximately 17% and 4%, respectively. K E Y

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“…Nowadays, single dual-frequency receivers (i.e., only one GPS receiver) are used in many applications, such as the precise point positioning (PPP) technique for geohazard monitoring, crustal-deformation monitoring, ocean tide measuring and, atmosphere water vapour sensing among others, in GNSS-remote sensing (see, e.g., KHANDU et al, 2011;AWANGE, 2008;GENG et al, 2011;JIN et al, 2011). In these examples, the GPS signal could be temporarily lost due to the obstruction of the signal between the GPS satellite and the receiver antenna.…”

Section: Introductionmentioning

confidence: 99%

Study on cycle-slip detection and repair methods for a single dual-frequency global positioning system (GPS) receiver

Hieu¹,

Ferreira

et al. 2014

Bol. Ciênc. Geod.

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In this work, we assessed the performance of the cycle-slip detection methods: Turbo Edit (TE), Melbourne-Wübbena wide-lane ambiguity (MWWL) and forward and backward moving window averaging (FBMWA). The TE and MWWL methods were combined with ionospheric total electron content rate (TECR), and the FBMWA with second-order time-difference phase ionosphere residual (STPIR) and TECR. Under different scenarios, 10 Global Positioning System (GPS) datasets were used to assess the performance of the methods for cycle-slip detection. The MWWL-TECR delivered the best performance in detecting cycle-slips for 1 s data. The relative comparisons show that the FBMWA-TECR method performed slightly Author to whom correspondence should be addressed.

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Towards PPP-RTK: Ambiguity resolution in real-time precise point positioning

Cited by 224 publications

References 20 publications

Rapid re-convergences to ambiguity-fixed solutions in precise point positioning

Rapid re-convergences to ambiguity-fixed solutions in precise point positioning

GLONASS Aided GPS Ambiguity Fixed Precise Point Positioning

Study on cycle-slip detection and repair methods for a single dual-frequency global positioning system (GPS) receiver

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