RST310 USER & INSTALLATION MANUAL
46
Symptoms of RF Interference
Symptoms of RF interference often resemble those that arise when an Iridium phone
is being operated with an obstructed view of the sky.
Some of these symptoms include; erratic or no signal strength indication, dropped
calls or warbled or otherwise distorted voice.
These symptoms may be intermittent or persistent, depending largely on the
interference source, its distance, strength and frequency relative to the Iridium unit.
Mitigation of RF Interference
Degradation of service due to RF interference to the Iridium unit can be significantly
improved by either or both of the following:
a) Increasing the distance and moving the Iridium antenna off axis from the
source of the interference, and
b) b) Using an external band pass filter and an external antenna.
In determining the optimal location for mounting an external Iridium antenna in a
location where INMARSAT antennas are also located, be certain that the Iridium
antenna is mounted either to the side or behind the INMARSAT antenna, and above
or below it.
Also note that the length of the feed line (the cable running from the Iridium unit to
the antenna) plays an important role in the performance of the unit.
In addition to installing the Iridium antenna off-axis and away from the INMARSAT
antenna, installing a band pass filter between the Iridium unit and its external
antenna will provide the best protection from RF interference and degraded
performance. The use of a band pass filter, which at the present time is designed for
fixed installations only, will significantly improve the overall performance of the
Iridium terminal.
Recommended Operating Distances:
Inmarsat Mini-M
Recommended Distance Between an Iridium Unit and an Active Inmarsat Mini-M
Terminal Antenna
• Main Lobe = directly in front and in line
with the Inmarsat terminal antenna:
225 feet (68 meters)
• Side Lobe = directly to the side and in
line with the Inmarsat terminal antenna:
100 feet (30 meters)
• Rear Lobe = directly to the rear and in
line with the Inmarsat terminal antenna:
50 feet (15 meters)
