Technical data

Chapter 2 - Installation
Case 2
In case that the GPS antenna is not exposed to direct lightning hit it is
recommended to use the regular protection set on the antenna side and
at the indoor side.
 Minimize the exposure of the antenna cable to electrically induced
fields. This is easily achieved by feeding the cable down the center
of the pole used to mount the bracket.
 Ensure all conduits exposed to induced fields are of heavy gauge,
welded seam construction, and are properly grounded.
 NEVER work on any part of the installation or cabling when there
are weather conditions that may result in lightning strikes or corona
discharge.
Protection against Lightning
During installation, it is essential to include a method of affording
protection from the effects of a lightning strike. The example described
in the following text enables a reasonable amount of predictability to the
outcome of a strike. Without such provision, the discharge current will
flow directly through the GPS Receiver installation, usually
destructively.
CAUTION
This provision of a low impedance path is mandatory.
In addition, it is imperative that the building is fitted with a suitable lightning conductor &
lightning rod.
At the Antenna
A proprietary Lightning Arrestor should be installed, of a type which
does not reduce GPS signal transfer. Install the lightning arrestor near
to the antenna (e.g. on the mounting pole), ensuring all connections
maintain electrical and environmental protection.
The GPS Receiver and other equipment in the receiver rack should be
protected from lightning using two co-axial gas discharge tube protectors
which should be connected close to the top of the antenna tower and at
the input bulkhead respectively.
It is also desirable to route the coaxial cable inside the pole if possible,
or alternatively, secure the coaxial cable securely to the pole. Avoid
sharp bends or angles in the routing of both the cable and the main
grounding connection.
GPS Timing Receiver Installation and Operation Manual
2-6