Global Positioning System Reference
In-Depth Information
MTSAT
Sapporo GMS
Ground communication line
Kobe MCS
Hitachi-Ohta MCS
Fukuoka GMS
Tokyo
GMS
Hawaii MRS
Naha GMS
Australia MRS
MCS Master control station
MRS Monitor and ranging station
GMS Ground monitor station
Figure 8.28
MSAS ground network.
whose signals are distorted or whose clocks are running erratically, in case of which
the SBAS user may be sent the warning: “do not use”). These estimates and integrity
information are used to form wide-area differential corrections and integrity mes-
sages that are then forwarded to the satellite uplink facilities. At the uplink facilities,
the spread spectrum navigation signal is generated and precisely synchronized to a
reference time and modulated with the SBAS data. This composite signal is continu-
ously transmitted to a geostationary satellite. On board the satellite, this navigation
signal is frequency translated within the navigation payload and transmitted to the
user on the GPS L1 frequency. The timing of the signal is done in a very precise man-
ner in order that the signal appears as though it was generated on board the satellite
as a GPS ranging signal. Redundant central processing and uplink facilities may be
used to provide hot standbys in the event of a failure at the primary facility.
SBAS Signal Structure
The signal broadcast via the SBAS geostationary satellite to the SBAS users [52] is
designed to minimize standard GPS receiver hardware modifications. The GPS L1
Search WWH ::




Custom Search