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Using one GPS Antenna Over Multiple Chartplotters Using the Marine Network or NMEA 2000
The Garmin® Marine Network or the NMEA 2000 network can have multiple antennas installed. One antenna can be shared across all chartplotters.
NMEA 0183 Connected Antennas
An installed GPS 19x HVS or the GPS 24xd antenna between multiple chartplotters connected via the Garmin Marine Network, the chartplotters will be able to share one antenna. Some installations or user preferences for multiple antennas provide for redundancy. The recommendation, in this case, is to wire both antennas to the chartplotter the same way, but both antennas cannot be used at the same time. Connect the antennas to a switch to turn on or off one or the other to resolve this. The easiest way to install the switches will be to connect the black (ground) wire from the antennas directly to their own switch. Then, the switch would be connected to the ground. This would allow one antenna to be turned on while the other is turned off. If a problem occurs when using one antenna, it can be switched off, and the other antenna switched on.
NMEA 2000 Connected Antennas
If the GPS 19x or the GPS 24xd NMEA 2000 antenna is used, the position data shares between all chartplotters connected through the Marine Network and the NMEA 2000 network. Multiple antennas on a vessel require the designation of one antenna as receiving the GPS signal.
To change this setting on a Current GPSMAP™ chartplotter1 follow these instructions: select Options > Settings > System > GPS > Source. From this menu, select which unit or antenna is the primary source.
Designating an antenna dictates all connected devices, the source for GPS data to be consistent across the network. The user can change the selected antenna at any time.
1Legacy Series Chartplotters have different menu paths see owner's manual, Finding the Owner's Manual for a Garmin Device