Sea Tel 9797B-70 C-Band TX/RX Installation And Operation Manual Download

Page: 34 / 110

Setup

9797B-70 C-Band TXRX

5-6

CAUTION:

The

Lower

Relative AZ limit is the more

counter-clockwise

the two points (even if it is numerically larger) and the

Upper

Relative AZ

limit is the more clockwise of the two points. If you enter the two relative
points incorrectly, Tracking and Searching will be adversely affected.

The ACU provides a contact closure to ground on the SW2 terminal of the Terminal Mounting Strip when the
antenna is pointed within any one of the blockage/hazard zones or the system is searching, targeting,
unwrapping or is mis-pointed by 0.5 degrees or more (FCC TX Mute function for Transmit/Receive systems

only

). The contact closure is a transistor switch with a current sinking capability of 0.5 Amp. Pressing the 5

key when the TRACKING window is selected can

simulate

a manual BLOCKED condition to test SW2 logic

output. UP arrow key is pressed to turn the simulated blocked condition OFF.

When used as simple “

BLOCKED

” logic output for a single Sea Tel antenna, this output could be used to light

a remote LED and/or sound a buzzer to alert someone that the antenna is blocked, and therefore signal is lost.
In a “Dual Antenna” installation, this logic output(s) is used to control Dual Antenna Arbitrator panel of coax
switch (or switches) to switch the source inputs to the matrix switch from Antenna

“A”

to Antenna

“B”

, 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 provides a

ground

to “Mute” the satellite

modem from the SW2 terminal of the Terminal Mounting Strip. If your satellite modem requires an

open

“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