Sea Tel 4009-9 BROADBAND-AT-SEA, Руководство по установке

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4009-9 Installation Manual Setup – Blockage & RF Radiation Hazard Zones
11-2
In a “Dual Antenna” installation, this logic output is also used to control a Dual Antenna Arbitrator panel to switch
the TXIF & RXIF signals from Antenna
“A” to Antenna “B” when Antenna “A” is blocked, and vice versa.
When used as simple “ RF Radiation Hazard ” logic output for a single Sea Tel TXRX antenna, this output could be
used to suppress RF transmissions while the antenna is pointed where people would be harmed by the
transmitted microwave RF power output. The SW2 output would be interfaced to the satellite modem to disable
the TX output signal from the Satellite TXRX Modem whenever the antenna is within the RF Radiation Hazard
zone(s).
When used for “
FCC TX Mute ” logic output for a single Sea Tel TXRX antenna, this output is used to suppress RF
transmissions whenever the antenna is mis-pointed 0.5 degrees or more, is blocked, searching, targeting or
unwrapping. The SW2 output would be interfaced to the satellite modem to disable/mute the TX output signal
from the Satellite TXRX Modem. When the mute condition is due to antenna mis-pointing, it will not un-mute
until the pointing error of the antenna is within 0.2 degrees. The default output is contact closure to ground when
the antenna is mis-pointed, therefore providing a
ground to “Mute” the satellite modem from the SW2 terminal
of the Terminal Mounting Strip. If your satellite modem requires an open to “Mute”, refer to SYSTEM TYPE
parameter 16 value to reverse the output logic from the ACU.
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 (in AZ LIMIT pairs).
In unlimited antenna systems the Relative position of the antenna must have been calibrated by properly setting
the Home Flag Offset (HFO) value in the PCU. The HFO calibrates Relative to display 0000 when the antenna is
pointed in-line with the bow of the boat/ship (parallel to the bow).
Convert the relative readings to AZ LIMIT/EL LIMIT values by multiplying by 10. Enter the beginning of the first
blockage region as AZ LIMIT 1 and the end of the region (clockwise direction from AZ LIMIT 1) as AZ LIMIT 2
parameters in the ACU. If needed, repeat setting AZ LIMIT 3 & 4 for a second ZONE and then AZ LIMIT 5 & 6 if a
third ZONE is needed. All unneeded zone AZ LIMIT pairs must be set to 0000. Set the upper elevation limit of
each blockage zone (also entered in degrees multiplied by 10).
EXAMPLE 1 - Three blockage Zones: A ship has a Sea Tel
antenna mounted on the port side and an Inmarsat
antenna mounted on the starboard side. A mast forward,
the Inmarsat antenna to starboard and an engine exhaust
stack aft form the three zones where satellite signal is
blocked (as shown in the graphic). In this example zone 1
is caused by the mast, zone 2 is from the Inmarsat
antenna, zone 3 is from the stack and zone 4 is not
needed:
ZONE 1 begins (AZ LIMIT 1) at 12 degrees
Relative and ends (AZ LIMIT 2) at 18 degrees
Relative. Multiply these Relative positions by 10.
Enter AZ LIMIT 1 value of 0120 and AZ LIMIT 2
value of 0180. In this case the mast height only
causes blockage up to an elevation of 50 degrees,
so we set EL LIMIT 12 to 0500. If the antenna is
between these two AZ Limit points but the
elevation is greater than 50 degrees, the antenna
will no longer be blocked.
ZONE 2 begins (AZ LIMIT 3) at 82 degrees Relative and ends (AZ LIMIT 4) at 106 degrees Relative.
Multiply these Relative positions by 10. Enter AZ LIMIT 3 value of 0820 and AZ LIMIT 4 value of 1060. In
this case the Inmarsat antenna height only causes blockage up to an elevation of 12 degrees, so we set EL