Note
Although the module may not detect the presence of very low-
power GPS antennas, it can still function correctly. Note that the LED and
software may report antenna error under these conditions, and if the
current consumed is close to the detection threshold the LED may flicker.
Refer to the Specifications section for more details.
Connecting the NI 9467
The NI-9467 has one SMA female connector on its front panel for a GPS active
antenna. The connector provides a DC voltage to power the antenna and also serves
as input for the GPS RF signal.
Installing the Antenna
Caution
National Instruments recommends using a lightning arrester in
line with the GPS antenna installation to protect the NI-9467 and the C
Series system from possible damage and operators from injury in the
event of lightning.
The embedded GPS receiver in the NI-9467 requires signals from several satellites to
compute accurate timing and location. The more satellites available to the receiver,
the more accurately it can determine time and location. Therefore, the antenna
location should be such that it receives signals from the greatest number of
satellites possible. As the number of satellites visible to the antenna decreases, the
synchronization performance may also decrease. Choose the antenna location so
that the antenna has a clear view of the sky. There is no strict definition for a clear
view of the sky, but a suitable guideline is that the GPS antenna should have a
straight line of sight to the sky in all directions (360°) down to an imaginary line
making a 30° angle with the ground. Locations far from trees and tall buildings that
could block or reflect GPS satellite signals are best.
Maximum Cable Length
Maximum cable length depends on the GPS antenna gain and the cable’s loss per
unit of distance. National Instruments recommends a GPS signal strength of
© National Instruments
7
NI-9467 Getting Started
