Reference : Rapid re-convergences to ambiguity-fixed solutions in precise point-positioning
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
Rapid re-convergences to ambiguity-fixed solutions in precise point-positioning
Geng, J. [University of Nottingham > Institute of Engineering Surveying and Space Geodesy]
Meng, X. [University of Nottingham > Institute of Engineering Surveying and Space Geodesy]
Dodson, A. H. [University of Nottingham > Institute of Engineering Surveying and Space Geodesy]
Ge, M. [> >]
Teferle, Felix Norman mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Engineering Research Unit >]
Journal of Geodesy
Springer Science & Business Media B.V.
Yes (verified by ORBilu)
[en] Precise Point Positioning ; Ambiguity Resolution ; Rapid Re-Convergence ; Predicted Ionospheric Delays ; Global Positioning System
[en] 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, 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 re- convergences 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 sky- view by most PPP applications and improve the practicability of real-time PPP.
Researchers ; Professionals

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