2: INSTALLATION
Iridium Pilot™ Installation Guide 11
Elevation Probability
The below graph shows the importance of low elevation visibility of the sky, where 90% of the time a
spacecraft will be less than 45° above the local horizon.
Obstructions Around the ADE
To ensure the best possible connection with the Iridium satellite network the ADE needs clear exposure, in all
directions, to the sky. Two types of obstructions that should be considered when deciding the placement of
the ADE include: metallic and superstructure obstructions.
The loss of signal (dB) will increase the closer the obstruction is to the ADE. The table below shows the
correlation between the size of the obstruction and the distance of the obstruction from the ADE and the
amount of signal loss.
Obstruction Signal Loss Table – Signal interference around the ADE
Diameter of Obstruction Obstruction Distance Signal Loss
.2 m (.7 ft.) < 2 m (6.5 ft.) 2 dB
< 4 m (13.1 ft.) 1 dB
.4 m (1.3 ft.) < 9 m (29.5 ft.) 2 dB
< 31 m (101.8 ft.) 1 dB
.6 m (2 ft.) < 22 m (72.2 ft.) 2 dB
< 75 m (246 ft.) 1 dB
.8 m (2.6 ft.) < 40 m (131.2 ft.) 2 db
1 dB
1.0 m (3.3 ft.) < 65 m (213.2 ft.) 2 dB
1 dB
The ship’s RADAR and high power transmitters may cause signal interference.
To avoid possible damage to the ADE and degradation of ADE performance the unit must be mounted as far
away as practical from these units. In addition it should also be kept clear of other sources of interference such
as other Iridium or Inmarsat terminals.
The diagrams and tables below are only guidelines as the minimum distances will be dependent on the exact
transmitter characteristics as well as reections from masts, decks and other items in the vicinity of the ADE.
The tables for X and S-band radar distances are minimum distances to avoid damage to the ADE and do not
necessarily guarantee a good communication link.
Minimum Distance from S-band & X-band RADARs
S-band (- 10 cm / 3 GHz) radars
Radar Power Min distance at 15˚ vertical separation Min distance at 60˚ vertical separation
0 – 10kW 0.4 m (1.3 ft.) 0.4 m (1.3 ft.)
30kW 1.0 m (3.3 ft.) 0.5 m (1.6 ft.)
50kW 2.0 m (6.6 ft.) 1.0 m (3.3 ft.)
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