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Setup – Blockage & RF Radiation Hazard Zones 5012-91 Installation Manual
10-1
10. Setup – Blockage & RF Radiation Hazard Zones
The Blockage Zones function inhibits the antenna from transmitting within certain pre-set zones. This is typically some
structure of the ship that prevents satellite signal from getting to the Sea Tel antenna when the ship is at headings that put that
structure in-between the satellite and the satellite antenna,
However, it can also be used as an RF Radiation Hazard zone. If there is an area where people may be near the antenna (within
2 meters), in the antennas transmitted beam for extended periods of time the zone can be set up so that transmit from the
satellite antenna will be disabled whenever the antenna is pointed in that zone.
10.1. Radiation Hazard and Blockage Mapping
The MXP can be programmed with relative azimuth sectors (zones) where blockage exists or where transmit power
would endanger personnel who are frequently in that area. Your MXP software allows you to set four zones.
When you create these ZONES (up to four), several things happen when the antenna is within any one of the zones:
1. Tracking continues as long as the AGC value is greater than the Threshold value. When the AGC value drops
below Threshold, the antenna will wait “Search Delay” parameter amount of time and then re-target the
satellite you targeted last. Timeout and re-target will continue until the satellite is re-acquired and tracking
can resume.
2. The satellite modem transmission will be disabled
until the antenna exits the zone.
The lower and upper azimuth limits are entered into the
REL start, REL stop and EL fields within the MXP for each of
the blockage zones you wish to create (up to four). Each
zone can also be given a name (ie Mast, Deckhouse or
Stack:
REL Start is the Lower Relative AZ limit (this is
the more counter-clockwise of the two points,
even if it is numerically larger).
REL Stop is the
Upper Relative AZ limit (the more clockwise of
the two points) for pattern mapping of each.
Enter the elevation value that represents the top
of the blockage between the two azimuth limit
points in the
EL
field.
Repeat for up to four zones, click SAVE when
completed.
Programming instructions:
Determine the Relative AZ positions
where
blockage, or
RF Radiation Hazard, exists. This may be done by
monitoring the received signal level and the REL display
readings while the ship turns or by graphing the expected
blockage pattern. Elevation of the antenna in normal use
also must be taken into consideration. A Mast or other
structure may cause blockage at low elevation angles, but
may not cause blockage when the antenna is at higher
elevation angles where it is able to look over the structure.
Up to four zones may be mapped. Only zones which are needed should be mapped.