User guide

Setting up Wideye Sabre 1 with BGAN LaunchPad Page 7
e. For subsequent use, the terminal will not acquire a new GPS, but will prompt the user if
previously stored GPS coordinates should be used.
f. Use the Up and Down Buttons to select Yes and then press Enter if stored coordinates
should be used, or select No and press Enter if a new GPS location is required, then repeat
steps a. through d.
About GPS
The Global Positioning System (GPS) uses 24 orbital satellites to fix the position of the
terminal anywhere on the globe.
• In normal operation, a GPS receiver, such as that built in to the Terminal, needs to
be able to receive signals from at least three satellites so that it can then calculate
latitude, a longitude and an altitude – this position fix is referred to as a 3-
dimensional or 3-D fix. If only two GPS satellites can be seen by the GPS receiver,
then the last available altitude measurement is assumed and the GPS receiver
calculates a position fix based on latitude and longitude only. This simpler position
fix is referred to as a 2-dimensional or 2-D fix and is quicker and easier to obtain
than a 3-D fix, but may be less accurate.
Note: You can register with the BGAN network with a 2-D or a 3-D fix.
• The GPS receiver may take between a few seconds and 20 minutes to obtain a GPS
fix, depending on how frequently the GPS receiver is being used. The frequency of
use determines the how quickly the GPS Terminal is able to start.
• Hot start - if the GPS receiver is being used frequently, (that is, at least every two
to six hours), it is regularly updated with data from the GPS satellites and so only
takes a short time to obtain a GPS fix after being switched on.
• Warm start - if a GPS receiver has not been used for more than six hours, then it
will take longer to obtain a GPS fix, perhaps up to 45 seconds.
• Cold start - if the GPS receiver has not been used for some time or is 300 km or
more from where it was last used, it can take between 10 and 20 minutes to
obtain a valid position fix.
• Following successful registration and providing the Terminal is left switched on and
remains stationary, the GPS is no longer needed. Periodically, the BGAN terminal
contacts the BGAN network to inform the network that it is still switched on. In
addition, the BGAN network periodically checks each terminal for activity and if
there has been no traffic through the terminal and the terminal has not automatically
contacted the BGAN network as described above, then the terminal will be de-
registered from the network.