A Prototype of Tropospheric Delay Correction in L1-SAIF Augmentation

Abstract

: L1-SAIF signal is one of the navigation signals of Quasi-Zenith Satellite System, which provides an augmentation function for mobile users in Japan. This paper presents the detail of the tropospheric delay correction in L1-SAIF augmentation. The tropospheric delay correction information is generated at the ground station using the data collected at GEONET (GPS Earth Observation NETwork) stations. The correction message contains the information of the zenith tropospheric delay (ZTD) values at 105 Tropospheric Grid Points (TGP) in the experiment area. From this message a mobile user can acquire the ZTD value at some neighboring TGPs, and estimate the local ZTD value accurately by using a suitable ZTD model function. Only 3 L1-SAIF messages are necessary to provide all of the tropospheric correction information. Several investigations using the actual data observed at many GEONET stations overall Japan have proved that it is possible to achieve the correction accuracy of 13.2 mm (rms).

Tropospheric delay correction with dense GPS network in L1-SAIF augmentation

“…Based on these preliminary studies, the prototype of the tropospheric delay correction in the L1-SAIF augmentation was developed (Takeichi et al 2008). In addition to the prototype, the mask message system is introduced to facilitate an adoptive correction, and the message structure and the parameters in the estimation algorithm were improved.…”