Orolia GSG-5 Series, User Manual With Scpi Manual, Page: 100 / 392

the SBAS messages. These messages comprise different Message Types , one of which—
MT9—is used to update the satellite’s position and speed.
You can also select up to 3 specific satellites to simulate.
The SBAS satellites transmit their signals utilizing Coarse/Acquisition Pseudo-Random
Noise (see also
"Encryption" on page 81 ). PRN numbers , which have been internationally
coordinated, have been allocated to each of the SBAS constellations. Although PRN120 …
PRN158 are all reserved for SBAS systems, only a few of them are actually used by satel-
lites.
When determining the elevation angle of SBAS satellites, the GSG unit looks for the SBAS
satellites listed below. This is in contrast to the signal generator mode (see
"Signal Gen-
erator" on page 94 ) where the user can specify any SBAS PRNs to be simulated.
The currently supported SBAS satellites are:
EGNOS : 120, 123, and 136
WAAS : 131, 133, 135, and 138
MSAS : 129, 137
GAGAN : 127, 128, and 132
The simulator uses two approaches for SBAS messages:
Default SBAS messages (MT63)
EGNOS/WAAS message files
The default SBAS messages are always available. These messages should be recognized
by SBAS-compatible receivers. However, they carry no information and will therefore not
enable the receiver to correct GPS signals.
SBAS message files for both EGNOS, and WAAS are supported. EGNOS files (.ems) are
ASCII and hourly, while WAAS files are typically in binary format and cover a whole day.
Both
systems share the same format of the messages. For details, see
www.navipedia.net .
When the scenario has the Ephemeris set to Download , the GSG unit will download the
SBAS messages from official sites and match these messages to the time of the scenario.
The SBAS messages broadcast by these satellites are downloaded automatically from the
following public FTP sites:
EGNOS : ftp://131.176.49.48
WAAS :
ftp://ftp.nstb.tc.faa.gov
MSAS :
www.enri.go.jp
GAGAN :
default MT63
GSG logs into these sites anonymously. However, note that both FTP sites are likely to
track and record all FTP access, including access by GSG simulators.
84 User Manual GSG-5/6 Series Rev. 27
3.5 "Select" Menu