Installation Guide

V5 Node B Installation Guide
Version 1.0.5 Page 38 of 44
Step 12 GPS Installation & Operation
The Node B has an external/remote GPS antenna and receiver. The connection for the
antenna (N-Type) is located on the Control Shelf, Figure 5-17.
The GPS timing signal is used by the Node B for the TDD frame timing, so that all Node B's
in a network are synchronized. The GPS signal is also used by the master oscillator for a
frequency reference. The Node B can operate for two hours after a loss of GPS timing but a
gradual drift of the frame timing will result in system interference and a loss of Node B
selection / reselection capability.
A suitable Node B GPS antenna is shipped with every Node B. This antenna should be used
with a total cable attenuation of minimum 8dB to maximum 25dB with male N-type
connectors at each end. By example cable RG6 8dB  30m and 25dB  90m. For long runs,
the cable losses will affect signal strength and could impede GPS signal performance.
For proper operation of the GPS receiver, the Node B GPS Antenna must have a clear
southern view of the sky (northern hemisphere installations). A site survey should be done
before Node B installation to verify that the Node B installation location is suitable for GPS
reception.
A simple survey method is to take a handheld GPS receiver to the site and verify that GPS
lock is obtained in the location of the Node B installation. The handheld GPS should be able
to obtain a "locked" condition within 2 minutes of power-on, and should be able to see a
minimum of 4 satellites at all times.
The GPS receiver, integral to the Node B Control shelf, is automatically enabled when the
Node B is powered and there are no adjustments or settings to be made by the user.
Note: When the Node B installation is on or near a tower or building wall, the GPS survey
should replicate the configuration.
Figure 5-17 : GPS Antenna
GPS Antenna
Field of Vision No
Obstructions