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Performance Evaluation of the CNAV Broadcast Ephemeris

Published online by Cambridge University Press:  05 April 2019

Ahao Wang
Affiliation:
(College of Surveying and Geo-Informatics, Tong ji University, Shanghai 200092, China) (Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China)
Junping Chen*
Affiliation:
(Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China) (School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China) (Shanghai Key Laboratory of Space Navigation and Positioning Techniques, Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China)
Yize Zhang
Affiliation:
(Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China) (Tokyo University of Marine Science and Technology, Tokyo, 1358533, Japan)
Jiexian Wang
Affiliation:
(College of Surveying and Geo-Informatics, Tong ji University, Shanghai 200092, China)
Bin Wang
Affiliation:
(Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China)
*

Abstract

The new Global Positioning System (GPS) Civil Navigation Message (CNAV) has been transmitted by Block IIR-M and Block IIF satellites since April 2014, both on the L2C and L5 signals. Compared to the Legacy Navigation Message (LNAV), the CNAV message provides six additional parameters (two orbit parameters and four Inter-Signal Correction (ISC) parameters) for prospective civil users. Using the precise products of the International Global Navigation Satellite System Service (IGS), we evaluate the precision of satellite orbit, clock and ISCs of the CNAV. Additionally, the contribution of the six new parameters to GPS Single Point Positioning (SPP) is analysed using data from 22 selected Multi-Global Navigation Satellite System Experiment (MGEX) stations from a 30-day period. The results indicate that the CNAV/LNAV Signal-In-Space Range Error (SISRE) and orbit-only SISRE from January 2016 to March 2018 is of 0·5 m and 0·3 m respectively, which is improved in comparison with the results from an earlier period. The ISC precision of L1 Coarse/Acquisition (C/A) is better than 0·1 ns, and those of L2C and L5Q5 are about 0·4 ns. Remarkably, ISC correction has little effect on the single-frequency SPP for GPS users using civil signals (for example, L1C, L2C), whereas dual-frequency SPP with the consideration of ISCs results have an accuracy improvement of 18·6%, which is comparable with positioning accuracy based on an ionosphere-free combination of the L1P (Y) and L2P (Y) signals.

Type
Research Article
Copyright
Copyright © The Royal Institute of Navigation 2019 

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