Site preparation
2-13
2.2.7 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 FV-110 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
worst interference can be avoided by mounting the ADU at a different level – meaning
that the ADU is installed minimum 15° above or below the radar antenna. Due to near
field effects the benefit of this vertical separation could be reduced at short distances
between radar antenna and the FV-110 ADU. Therefore it is recommended to ensure as
much vertical separation as possible when the FV-110 ADU has to be placed close to a
radar antenna.
Do not place the ADU close to interfering signal sources or
receivers. For allowed distances to other transmitters see
Figure 2-12: Recommended distance to transmitters (m) for
frequencies below 1000 MHz on page 2-16. We recommend
testing the total system by operating all equipment
simultaneously and verifying that there is no interference.
Figure 2-11: Interference with the vessel’s radar
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