User Manual

RF-Baton! Transmitter Controller Installation and Operation Preinstallation
June 1999 6880497G01-B 3-3
Antenna Considerations
If the RF-B! transmitter controller contains an optional Global Positioning System (GPS)
receiver, the receiver must locate and track at least four satellites during initial power-up.
After power-up, the receiver tracks three satellite to maintain the timing signal. Because this
timing is critical for maintaining system synchronization, carefully evaluate any proposed
GPS antenna locations before installation to ensure an adequate lock can be obtained from the
proposed site. Ensure that the GPS antenna has a clear view of the sky.
GPS Evaluation Kit
The Motorola GPS evaluation kit (Model No. VPEVAL0002, GTEVAL0001, or UTEVAL0001)
provides a means of evaluating potential site and antenna mounting locations before site
acceptance and construction begin.
The evaluation kit includes the hardware and software programs and instructions necessary
for collecting site evaluation data. Use the kit to collect the following necessary data:
• Number of visible satellites
• Signal strength of tracked satellites
• Number of satellites being tracked
• Dilution of Precision (DOP) type (position or horizontal)
To order this kit, contact the Motorola Position & Navigation Systems Business that is listed in
the Foreword of this manual, or contact your Motorola representative.
The following paragraphs explain some of the procedures used to collect GPS data.
GPS Tracking Criteria
The GPS receiver must have a Position Dilution of Precision (PDOP) of less than 10 to
successfully initialize. A PDOP greater than 10 can delay start-up. To minimize delay, a PDOP
of greater than 10 for more than 30 minutes is not recommended.
Large PDOP values typically occur when tracking less than four satellites. Once operating
with the GPS locked, a PDOP of greater than 10 does not affect the site performance as long at
least three satellites are being tracked.