User Manual

Preinstallation RF-Baton! Transmitter Controller Installation and Operation
3-4 6880497G01-B June 1999
The GPS receiver must be able to achieve the following performance requirements:
• Track a minimum of four satellites for GPS receiver initialization that occurs after any
loss of power to the GPS receiver or any time the GPS almanac is cleared.
Note: Loss of power to the BCM does not imply loss of power to the GPS receiver.
• Maintain track on at least three satellites after GPS receiver initialization is complete.
• Not lose tracking of satellites for more than 96 minutes.
Proper GPS antenna installation is essential for obtaining optimal performance of the paging
station. When GPS antennas are improperly installed, and subsequent frequent and long loss
of GPS satellite tracking occurs, the simulcast capability of the station is greatly diminished
and longer system down-time can result.
GPS Antenna Requirements
The GPS antenna must be mounted with an unrestricted aerial view of within 10 degrees of
the horizon in all directions and high enough to clear the peak of any site roof.
For systems in the northern hemisphere, the GPS antennas must be mounted to provide a
clear view of the southern sky. For systems in the southern hemisphere, GPS antennas must be
mounted to provide a clear view of the northern sky.
Adjacent structures, such as trees or buildings, can obstruct signals. The GPS antenna must be
mounted clear of all obstructions to provide a clear path. Other adjacent antenna towers at the
RF site that protrude into the required view have a minimal effect on GPS satellite reception
and are not considered obstructions.
Maintain a distance of at least 38 dB (32.2 + 20logf
(MHz)
+ 20logD
(10/5-80)
= 37.3 dB) of path
loss (from a 1-Watt isotropic radiator) from any other antenna to prevent jamming the GPS
receiver signal.
Long runs of single-braided, shielded cable can subject the GPS receiver to jamming
interference. Use solid copper, outer conductor coaxial cable between the GPS antenna and
receiver.
Use a coaxial cable with specifications that satisfy the system gain requirements for the GPS
receiver, at a frequency of 1575.42 MHz (GPS-L1), to connect the GPS antenna to the GPS
receiver’s GPS input.