Installation Manual

DRAFT COPY
NOMAD MXU Installation Manual
3:36 PM 02/12/99
DRAFT COPY
12
4.2 Antenna Installation
WARNING
Electrical Storm Hazard
Electrical storms can cause the antennae to be charged to high voltages. Do not touch outside of
equipment, or grounding wires and rods during electrical storms. Failure to observe this warning
can cause serious injury or death.
4.2.1 Placement
Figure 4.2.1-1: Antenna Location, Un-obstructed Sky
The NOMAD MXU system relays telephone conversations via satellites in Low Earth Orbit (LEO) around
the world. Only one satellite at a time is in contact with the MXU console. Because of the rotation of the
earth, the satellite may be moving, in a south/north direction across any part of the sky, while it maintaining
contact with the MXU console. Before the satellite departs over the north horizon, it will hand off the
telephone conversation to the next satellite arriving on the south side of the horizon. If the antennas are not
correctly located, the satellites will not have a “line of sight” with the antennas and the service will be
unreliable.
The antennas must be located to provide a clear view of the sky, from horizon to horizon. Figure 4.2.1-1
illustrates three possible cases.
•
Case 1 The NOMAD MXU system will work intermittently because half of the sky is blocked by a
large building. This will result in some passing satellites not having a clear “line of sight” to the
antennas.
•
Case 2: This NOMAD MXU will probably work better than in case 1; however, depending on the size
of the tree, intermittent operation of the NOMAD MXU is probable because of the addition attenuation
and the periodic blockage of the signal between the antenna and satellites.
• Case 3: This will give the best operation of the NOMAD MXU system because there is direct “line of
sight” to the satellite regardless of its location in the sky.
Case 1: NO
Case 2: MAYBE
Case 3: YES
Maximun 8 degrees
above horizon
Maximun 8 degrees
above horizon