COBHAM Sea Tel 9711-56 IMA C Band, Руководство по установке

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Sea Tel 9711-56 IMA Setup – Blockage & RF Radiation Hazard Zones
10-1
EAR Controlled - ECCN EAR99
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.
EXAMPLE - Overlaid Blockage Zones: A ship has a Sea Tel antenna mounted on the center line of the ship.
A mast mounted on top of a deckhouse (like the picture above) is forward and an engine exhaust stack, also
on a deckhouse, is aft. These two blockage areas have wide azimuth blockage at lower elevations and then a
narrower azimuth area of blockage extends up to a higher value of elevation.