Site preparation
3-12 Chapter 3: Installation 98-150471-A02
3.2.7 Interference
The ADU must be mounted as far away as possible from the ship’s radar and high power
radio transmitters, because they may compromise the ADU performance. RF emission from
radars might actually damage the ADU. The SAILOR 900 VSAT High Power ADU itself may
also interfere with other radio systems.
Radar
It is difficult to give exact guidelines for the minimum distance between a radar and the
ADU because radar power, radiation pattern, frequency and pulse length/shape vary from
radar to radar. Further, the ADU is typically placed in the near field of the radar ADU and
reflections from masts, decks and other items in the vicinity of the radar are different from
ship to ship.
However, it is possible to give a few guidelines. Since a radar radiates a fan beam with a
horizontal beam width of a few degrees and a vertical beam width of up to +/- 15°, the
Mast with 2 braces
Max. free mast
length (steel),
(m)
Outer
Diameter
(mm)
Wall
Thickness
(mm)
Outer
Diameter
for brace
(mm)
Thickness
for
brace
(mm)
1.2 160 10 80 5.0
1.2 200 5 80 5.0
1.6 180 10 80 5.0
1.6 220 5 80 5.0
2 180 10 80 5.0
22405805.0
2.5 200 10 80 5.0
2.5 260 5 80 5.0
Table 3-4: Mast dimensions with 2 braces
Do not place the ADU close to interfering signal sources or receivers. For allowed
distances to other transmitters see Figure 3-12: Recommended distance to
transmitters (m) for frequencies below 1000 MHz on page 3-15. We
recommend testing the total system by operating all equipment simultaneously
and verifying that there is no interference.
SAILOR900HP.book Page 12 Monday, July 18, 2016 12:44 PM
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