Sierra Wireless MP 881W, User Manual

Page: 60 / 88

MP881W Modem User Guide
54 2130808
GPS protocols and commands
Note: The “MP 3G Modems
TAIP Reference manual”
(document #2130312) provides
a description of the TAIP
commands that can be used with
the MP modem. This is available
at
www.sierrawireless.com
.
Information about Trimble GPS
modules, including more
documentation on TAIP
commands, is available at
www.trimble.com
.
More information on NMEA
message standards is available
at
www.nmea.org
.
The GPS module supports two methods of reporting naviga ‐
tional information, using either the TAIP (Trimble ASCII
Interface Protocol) or NMEA (National Marine Electronics
Association) protocols. The GPS module is pre ‐ configured for
TAIP. If you are using a GPS application that requires data to
be reported according to the NMEA protocol, the MP modem
must be reconfigured using an AT command. (See the MP 3G
Modems AT Command Reference manual (document #2130810.)
NMEA is a reporting protocol only, while TAIP provides the
ability to send commands to the module to query for infor ‐
mation and configure reports. When the MP modem is set for
TAIP, commands can be sent to the MP modem in these ways:
• Using 3G Watcher
• Using AT commands
TAIP commands can be used to:
• Query the MP modem for its current position, heading,
and speed
• Enable and disable automatic reporting of GPS data, and
set the interval at which automatic reports are sent
• Configure the format of reports
GPS display in 3G Watcher
To view 3G Watcher’s GPS Display window, which reports
latitude, longitude, speed, direction, altitude, and local and
UTC time
1
, select
Tools > Display GPS
or double ‐ click the GPS
icon on the main 3G Watcher window.
From a cold start (where the MP modem is powered on with
no stored navigational data), it may take up to 39 seconds for
the GPS module to obtain satellite fixes and begin reporting.
1. UTC replaces Greenwich Mean Time as the basis for
standard time throughout the world. UTC, which uses
atomic measurements rather than the Earth’s rotation, is
the equivalent of mean solar time at the prime meridian
(0° longitude).