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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Ionospheric scintillation impact on ambiguity resolution using ADOP in closed form

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Silva, C. M. [1] ; Alves, D. B. M. [1] ; Souza, E. M. [2] ; Setti Junior, P. T. [1]
Total Authors: 4
[1] Sao Paulo State Univ, UNESP, Sch Technol & Sci, Presidente Prudente - Brazil
[2] Univ Estadual Maringa, UEM, Maringa, Parana - Brazil
Total Affiliations: 2
Document type: Journal article
Source: Advances in Space Research; v. 64, n. 4, p. 921-932, AUG 15 2019.
Web of Science Citations: 0

The Ambiguity Dilution of Precision (ADOP) is a well-known scalar measure that can be used to infer the strength of the Global Navigation Satellite System (GNSS) model of the carrier phase ambiguities involved in precise relative GNSS positioning. Odijk and Teunissen (2008a) derived closed-form expressions for single-baseline GNSS models that allow verifying the factors affecting the ambiguity resolution as well as the probability of its correct resolution as integer values. However, this weighted-ionosphere ADOP closed form assumes that the standard deviation of the ionosphere delay is dependent on a function associated with the baseline length. This means that a baseline of the same length at different locations around the world and in different moments in time would have the same standard deviation, which in practice is not true. This becomes even worse in regions like Brazil, where the ionospheric anomalies are more intense and frequent, especially in periods of high solar activity. In this work, a new method for calculating the ionospheric delay standard deviation that considers the ionospheric scintillation S4 index is proposed to improve the closed-form ADOP performance. Experiments with a baseline of 280 m located in Presidente Prudente, Brazil (magnetic latitude of around -13 degrees), were carried out. The results showed that in periods of both weak and strong ionospheric scintillation, the introduction of S4 into the ionospheric delay standard deviation was beneficial for ADOP. The average improvement of the ADOP closed form was of around 72% in the analyzed period of weak scintillation and of 35% in the period of strong scintillation. In addition, the results showed that in periods of strong scintillation, relative positioning accuracy is around 100 times worse, up to 30 m, when compared to periods of weak ionospheric scintillation. (C) 2019 COSPAR. Published by Elsevier Ltd. All rights reserved. (AU)

FAPESP's process: 12/19906-7 - Robust evaluation of atmospheric modeling impact in Network-Based positioning
Grantee:Daniele Barroca Marra Alves
Support type: Regular Research Grants
FAPESP's process: 13/06325-9 - Ambiguity resolution at network based positioning
Grantee:Crislaine Menezes da Silva
Support type: Scholarships in Brazil - Master
FAPESP's process: 16/24861-3 - GNSS point positioning: implementation and evaluation of new models, systems and signals
Grantee:Paulo de Tarso Setti Júnior
Support type: Scholarships in Brazil - Master