NorthStar Navigation GM1708 961XD - Manual (Page 24)

SECTION TWO - Installation
Page 14 961 INSTALLATION MANUAL Revision A
Connectors
• Power connector (3-wire)
• TNC connector (control head #1)
• TNC connector (control head #2)
• I/O #1 interface connector (18-wire)
• I/O #2 interface connector (18-wire)
• GPS antenna connector (BNC)
• DGPS antenna connector (UHF)
• PC connectors (variable)
• VGA
Installing the antenna
Choosing an
antenna
Three antenna choices are available for the 961X or 961XD:
• one for reception of GPS-only signals (the standard one-piece
“active” AN150 antenna)
• one for reception of both GPS and DGPS signals (a two-piece
antenna system comprising the standard AN150 GPS antenna and
the 8410 DGPS coupler)
• one for reception of both GPS and DGPS signals (optional one-piece
AN205-P “combination” antenna)
Choosing an
antenna location
Choosing the AN150 antenna location
The GPS receiving antenna is a vital link between the unit’s receiver and
the outside world. Aesthetics and easy access should be secondary to pro-
viding strong and reliable GPS signals to the unit’s receiver. You should
select a location for the antenna that meets the following requirements:
• The antenna should have a reasonably clear view of the horizon,
but be no higher than necessary (side-to-side motion of the
antenna caused by rolling of the vessel may degrade the SOG and
COG readings); however, the antenna should be 12 to 18 inches
above the surrounding surfaces to avoid interference.
• The antenna must be out of the radiation path of any on-board
radar sets or strong magnetic fields.
• The antenna must be lower than any INMARSAT communications
antenna.
• The antenna should be as far as possible from other high-power
transmitting antennas.
• Watch out for electromagnetic “shading” of antennas from rigging,
other vessels, shoreline buildings, and so on. Secure the cable well.