User Manual

VoiceXtender Modem Installer’s Guide
System Planning
Rev. A - 8/97 2-11
Figure 2-6
Hub Application
You need to configure each modem. The following list describes the parameters
for this particular application.
❚ RF Channel: Each AirLink modem pair is assigned a unique channel to
avoid interference. In this example, channels 1, 3, and 5 are recommended.
(SW1-1, 1-2, 1-3, 1-4)
❚ Transmit Output Power: Typically, the minimum required power is
recommended for most applications. However, the transmit power for the
slave modems must be set to minimize the adjacent channel interference at
the hub units.
(SW1-5, 1-6, 1-7)
❚ Burst Synchronization Timing: In a hub configuration where there are
multiple modem pairs, it is critical that all the master modems transmit
and receive at the same time to minimize inter-channel interference.
In this case, one modem (the synchronizing unit) is configured for internal
burst timing. All other master modems (the synchronized units) are
configured for external burst timing and synchronize their transmit bursts to
the signal from the synchronizing master. The slave modems are configured
for internal burst timing and derive their burst synchronization from their
received RF signal.
(SW1-8)
❚ Phone/Line: On the master modems, the Phone/Line switch must be set to
the Line position. On the slave modems, the Phone/Line switch must be set
to the Phone position.
(SW2-1)