Quality assessment of CNES real-time ionospheric products
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Real-time single-frequency precise point positioning (RT-SF-PPP) has become a desired positioning approach because it can achieve high positioning accuracy with a low-cost global navigation satellite system (GNSS) chipset or receiver. For single-frequency precise point positioning (SF-PPP) applications, the ionospheric delay is a dominant error source, and thus the quality of applied ionospheric products is critical to the performance of SF-PPP. To meet the demands of the RT-SF-PPP users, the international GNSS service (IGS) is planning to provide open-access real-time ionospheric products. By now, the Centre National d’Études Spatiales (CNES) is the only IGS analysis center (AC) to broadcast real-time ionospheric vertical total electron content (VTEC) message through its real-time service (RTS). The quality of the CNES real-time ionospheric products is drawing increasing attention from the GNSS community. We evaluate the quality of CNES real-time VTEC message both in the ionospheric correction domain and positioning domain. First, 374 consecutive days of CNES VTEC products are collected and compared with the IGS final global ionospheric map (GIM) products. Second, slant total electron content (STEC) computed with CNES VTEC message is fully assessed with respect to STEC derived from dual-frequency GNSS measurements. Finally, RT-SF-PPP is conducted for assessing the quality of CNES real-time ionospheric products in the positioning domain. The degree and order of the spherical harmonic expansions broadcasted in the CNES VTEC messages changed from 6 to 12 in the time span of collected data, the effects of higher degree and order parameters are investigated at the same time in the experiments above.
KeywordsReal time SF-PPP CNES VTEC STEC
This study was supported by Key Program of National Natural Science Foundation of China (Grant No.: 41631073), National Natural Science Foundation of China (Grant No.: 41604027) and Qingdao National Laboratory for Marine Science and Technology (Grant No.: QNLM2016ORP0401). The authors acknowledge Denis Laurichesse from CNES for valuable discussions. CNES and IGS are thanked for providing the experiment data. In addition, the anonymous reviewers are greatly thanked for their remarks and suggestions.
- Bisnath S, Gao Y (2009) Current state of precise point positioning and future prospects and limitations. In: Sideris MG (ed) Observing our changing earth, vol 133. Springer, Berlin International Association of Geodesy SymposiaGoogle Scholar
- Choy S (2009) An investigation into the accuracy of single frequency PPP. Dissertation, RMIT University, AustraliaGoogle Scholar
- Gao Y, Zhang Y, Chen K (2006) Development of a real-time single-frequency precise point positioning system and test results. In: Proc. ION GNSS 2006, Institute of Navigation, Fort Worth, Texas, USA, Sept. 26–29, pp 2297–2303Google Scholar
- Roma D, Hernandez M, Garcia-Rigo A, Laurichesse D, Schmidt M, Erdogan E, Yuan Y, Li Z, Gómez-Cama JM, Krankowski A (2016) Real time global ionospheric maps: a low latency alternative to traditional GIMs. 19th International Beacon Satellite Symposium (BSS 2016), Trieste, Italy, 27 June–1 July, p 1Google Scholar
- RTCM Special Committee (2014) Proposal of new RTCM SSR Messages, SSR Stage 2: Vertical TEC (VTEC) for RTCM Standard 10403.2 Differential GNSS (Global Navigation Satellite Systems) Services-Version 3. RTCM Special Committee No. 104, USAGoogle Scholar
- RTCM Special Committee (2016) RTCM Standard 10403.3 differential GNSS (Global Navigation Satellite Systems) Services-Version 3. RTCM Special Committee No. 104, Arlington, TX, USAGoogle Scholar
- Schaer S (1999) Mapping and predicting the Earth’s ionosphere using the Global Positioning System. Dissertation, University of Berne, SwitzerlandGoogle Scholar
- Weber G, Mervart L, Lukes Z, Rocken C, Dousa J (2007) Real-time clock and orbit corrections for improved point positioning via NTRIP. Proc. ION GNSS 2007, Institute of Navigation, Fort Worth, TX, USA, Sept 25–28, 1992–1998Google Scholar