Appendix C Installing The Gps Antenna; Antenna Kits And Accessories; Selecting The Proper Gain Antenna - Symmetricom TimeProvider 100 User Manual

Appendix C Installing the GPS Antenna

The GPS L1 Reference Antenna is one component of a complete line of GPS
accessories for your GPS antenna system provided by Symmetricom. These
accessories are designed to deliver precise GPS signals over a wide temperature
range and in harsh environmental conditions.
In This Appendix

Antenna Kits and Accessories


Installing the Antenna

Technical Support

Antenna Kits and Accessories
This section provides a list of antenna kits and accessories as well as descriptions
and associated part numbers.

Selecting the Proper Gain Antenna

When installing the GPS radio receiver, it is important to select the proper gain
antenna and coaxial cable that accounts for the insertion loss between the antenna
and the radio receiver to avoid under-driving or over-driving the radio receiver
antenna input. The gain required at 1575 MHz for a GPS radio receiver input is the
manufacturer's specification for the radio receiver to acquire satellites, with some
level of signal degradation allowed.
L1 Antenna gains are usually specified as the minimum effective gain. Such
antenna gains can have 4.5 to 10 dB more signal strength at different satellite
azimuths and elevations, depending on their reception pattern. The GPS engine
requires a signal level at the antenna connector input of the chassis to be between
25 dB and 35 dB. This tolerance allows for the signal loss of the internal coaxial
cable and connectors. The optimal signal level at the radio receiver input is 30 dB.
All antenna kits include the GPS L1 antenna, mounting pipe, floor flange, transient
eliminator, pre-assembled coaxial cable (for antenna to transient eliminator), roll of
3M 2150 weatherproof tape, and a right angle adapter. All chassis, antennas,
transient eliminators, and in-line amplifiers have N-type connectors.
All antenna kits supplied use LMR-400, or equivalent, low-loss coaxial cable. Other
types of coaxial cable are available for GPS antenna applications; however, it is
imperative that you calculate the specific cable loss to ensure a signal level
between 25 dB and 35 dB at the antenna connector input. The L1 signal loss of
LMR-400 is 0.167 dB/meter. The L1 signal loss of a 90 V transient eliminator is
typically 0.25 dB.
098-00106-000 Revision A – March, 2009 TimeProvider 100 User's Guide 107