User Manual Part 2

3-11

RF-7800B

OPERATION

2. Monitor the Web interface PROPERTIES page GPS Position information to determine when a

GPS Fix is obtained. Typically, a GPS 3D fix can be successfully attained in less than 90 seconds.

Refer to Paragraph 3.7.1.

Automatic tracking keeps the antenna pointed towards the satellite once the vehicle starts moving. During short

outages (while driving under a bridge, for example), the antenna will remain in the same position and will pick up

the satellite signal immediately upon exiting the blockage. For longer outages, the antenna may need to repeat the

search pattern to reacquire the satellite signal.

Circuit switched and packet switched connections will recover from signal outages, as the antenna will perform a

360 degree rescan every 15-20 seconds. In this case, the BGAN terminal will still remain Registered on the network.

For outages longer than 60 minutes, the BGAN terminal will need to re-register prior to activating additional circuit

or packet switched connections. Refer to Paragraph 4.3.4 to reactivate a connection.

3.7 BGAN SERVICES

BGAN requires GPS for registration with the BGAN network, for both circuit and packet switched connections. For

emergency circuit switched voice connections, GPS is not required. Both the RF-7800B-DU024 and the RF-7800B-

VU104 BGAN terminals contain an embedded GPS receiver. The BGAN terminal keeps a record of its last GPS fix

acquired between power cycles. If the BGAN terminal has not moved far since it last acquired a GPS fix (i.e.,

remained in the same spot beam), then it can register from the stored GPS position. If the BGAN Terminal attempts

to register before it acquires a new GPS fix, it will attempt to register and connect based on the stored GPS fix. If

the stored GPS fix does not allow it to connect successfully, the BGAN terminal will wait for a new GPS fix and

then complete the registration and connection.

3.7.1 Obtaining a GPS Fix

In normal operation, a GPS receiver needs to be able to receive signals from at least four satellites so that it can then

calculate a latitude, a longitude and an altitude. This position fix is referred to as a 3-dimensional or 3-D fix. If only

three 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.

The embedded GPS receiver, with a clear view of the sky, normally takes between 60 and 90 seconds to attain a 3-

D GPS fix. How quickly the GPS receiver is able to acquire a fix can also be affected by the visibility that the GPS

receiver has of the GPS satellites. The GPS system is relatively tolerant of atmospheric conditions such as heavy

cloud or rainfall. However, physical blockages, such as tall buildings or terrain can significantly degrade the ability

of the GPS receiver to obtain a fix. For this reason, ensure that the GPS receiver has a clear view of as much open

sky as possible.

3.7.2 GPS and BGAN Registration

The BGAN terminal uses the GPS information to perform both Registration, as well as the creation of packet and

circuit switched voice and data connections. BGAN Terminal Registration is performed in a Regional Beam,

whereas voice and data connections utilize BGAN Spot Beams. The GPS information instructs which Regional

Beam to register on, as well as what spot beam the BGAN terminal will create the voice or data connection on. If a

packet switched connection has been inactive for some time

, the BGAN network may remove the connection,

placing the BGAN terminal back in a Regi

stered state. When additional IP data is required to be transferred from

the BGAN terminal to the network, the terminal will automatically recreate the packet switched connection. This

will place the terminal back into a connected state.