3

Augmentation systems

3.1

Satellite_based augmentation system

Teseo-LIV4F supports SBAS. SBAS is a wide area differential GPS (WADGPS). It is a system which provides

differential GPS corrections data; SBAS includes the WAAS within the united states, the EGNOS within Europe,

the multifunctional transport satellite (MTSAT)-based MSAS within Japan and southeast Asia, and the GPS and

GEO augmented navigation (GAGAN) system in India.

The SBAS data correction is used in the GNSS algorithm to provide a better position estimation. The overall

SBAS differential correction mechanism can be conceived as built in 2 phases:

•

The “Acquire and tracking” phase.

•

The “Decoding” phase.

The “Acquire and track” phase relates to the capacity of the acquisition engine to reliably track the configured

SBAS satellite; during decoding phase the SBAS message can be decoded to fetch the differential corrections.

The current longitude limits for each service are:

•

WAAS -180 degrees to -25 degrees

•

EGNOS -25 degrees to +50 degrees

•

GAGAN +50 degrees to +100 degrees

•

MSAS +100 degrees to +180 degrees

The Teseo-LIV4F software with SBAS capability implements a command interface at the NMEA level to allow

interaction with the SBAS library. It supports commands to enable/disable the SBAS functionality.

3.2

QZSS

The quasi-zenith satellite system (QZSS) is Japanese regional communication services and positioning

information for the mobile environment in the GPS L1C/A band. QZSS in conjunction with GPS signals provide

GNSS augmentation service for the Pacific region covering Japan and Australia. QZSS satellites are placed in a

periodic highly elliptical orbit (HEO): these orbits allow the satellites to “dwell” for more than 12 hours a day at an

elevation above 70° (it means that they appear almost overhead most of the time).

Teseo-LIV4F

Augmentation systems

DS13957 - Rev 6

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