NMEA multiplexer combine multiple inputs

What is an NMEA Multiplexer?

This feature is useful if you have several devices that generate NMEA data, and you want to combine the data from those devices. This can, for example, be AIS + GPS data.

GpsGate Splitter can combine NMEA input from several inputs and merge it into one stream. This stream can typically be streamed over a network using UDP or TCP/IP. And it can be received and split up again at some other computer by GpsGate Splitter. Another option is to merge a set of NMEA inputs and stream it to one virtual port to which a GPS/NMEA application is connected that can handle the merged stream of NMEA data. The merged stream can also be saved by the GPS/NMEA Logger for later replay.

Setting up the inputs

1. Open the Input tab in the Settings dialog.

2. Select Use multiple inputs (MUX).


3. Then add all inputs you want to collect NMEA data from.

Note you can add an NMEA filter to each input.


Setting up the Outputs

1. Open the Output tab.

2. Add all Outputs you want to forward NMEA data to.

Note that some of the Output plugins like Virtual Port/NMEA Filter and UDP Sender/NMEA Filter have filters you can use to selectively forward certain NMEA data.

Advanced: It is possible to add an NMEA Filter to any of the plugins like TCP/IP by editing the ggxml files you find in the Chains folder.


Find active GPS using MUX input

The NMEA MUX can also be used to switch between several connected GPS/NMEA devices to find and use one valid signal. In the MUX settings dialog, there is an Option… button. Click it to select which mode the MUX should operate in.


  • Receive (MUX) data from all inputs - This is the default mode. Data from all added Inputs will be merged into one stream.
  • Find input with GPS data - In this mode GpsGate Client will find one input with valid NMEA data. If this signal is lost GpsGate will start searching again for a valid source of NMEA data among the added Inputs. The NMEA signal does not need to contain a valid GPS position.
  • Find input with valid GPS position - This works like the above option, except that GpsGate Client will continue to search for a signal with a valid GPS position.
  • Close all inputs when no outputs opened - When selected GpsGate Client will close all Inputs when no applications are connected to the GpsGate Splitter outputs. This can be used to save battery.