This paper aims to evaluate the potential error involved
in the application of the recommended algorithms and the
consequent effects on the positioning errors, under
typical atmospheric conditions for MSAS (Multi-
Functional Transport Satellite Satellite-based
Augmentation System). The results and analysis
presented in this paper will serve as benchmark for
further development of MSAS.
In order to assess the accuracy of Wide Area
Augmentation System (WAAS) atmospheric models and
their applicability to the Japanese MSAS, different
analyses were carried out. Japan has different climates
according to the region because of the North-South
length. Airport locations and the weather in Japan were
first studied. Tropospheric delay corrections obtained from the SBAS model were compared with Saastamoinen
and Hopfield models that use temperature, air and vapor
pressures as their input. The normal values for such
meteorological parameters were taken from the Rika
Nempyo (Chronological Scientific Tables) published by
the National Astronomical Observatory of Japan.
The data from flight tests conducted in the summer and
winter as well as data for a week collected at 2 control
stations were processed and analyzed. The stations
located near Sendai and Naha airports were selected.
Relative comparisons for positioning using different
atmospheric correction models were made and
preliminary results were obtained.
The differences in height (vertical component of
position) brought using different tropospheric correction
models were less than 50 cm from our results. The SBAS
troposheric model would be applicable to Japanese
MSAS. The use of different ionospheric correction
models (Klobuchar and dual frequency) provided the
difference of 2.5 m in vertical component. Development
of a correcion model for the ionosphere would be
necessary. Some areas occasionally have poor satellite
geometry. A ranging capability of MTSAT would be
important in some areas over Japan.
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