The L1-SAIF (L1 Submeter-class Augmentation with Integrity Function) signal is one of the QuasiZenith Satellite System (QZSS) navigation signals, which provides an augmentation function for mobile users in Japan. The tropospheric delay correction in the L1-SAIF augmentation is discussed in detail. Because the topographical features in Japan are complicated, the correction information is generated from GPS observation data collected at 200 GPS stations which are densely distributed over Japan. A total of 210 Tropospheric Grid Points (TGPs) are arranged to fully cover Japan. The TGPs that provide the correction information are selected adaptively to achieve the expected correction accuracy. This selection of TGPs is provided by the TGP mask message. Mobile users acquire the zenith tropospheric delay (ZTD) value at neighboring TGPs from the correction messages, and can estimate the local ZTD value accurately by using a suitable ZTD model. Only up to seven L1-SAIF messages are sufficient to provide the full correction information. Accuracy evaluations have proven that it is possible to achieve a correction accuracy of 13.4 mm RMS. The strategy presented here has been implemented into the augmentation system using the L1-SAIF signal, and its application guidance is presented in the QZSS interface specification.
A ranging and positioning system for a ship or an aircraft using two geostationary satellites is described. This system has a ranging and positioning accuracy of 100 m and 1 km.Experiments to estimate this system were performed using a ship in the Pacific Ocean in a normal and a differential modes.This system leads to the development of fundamental ranging and positioning techniques for the cooperated independent surveillance.
In‐the aeronautical satellite system for the air traffic control in the oceanic area, it is important to know the position of aircraft at the ground earth station. This paper describes the ranging and positioning system using two geostationary satellites (real satellite and a pseudosatellite on the ground).
This system is designed to allow ranging and positioning of each aircraft every 0.6 s within the ranging and positioning accuracy of 100 m and 1 km, respectively. Experiments to estimate this system were performed using a real aircraft. Results gave better accuracy than those mentioned in the foregoing.
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