The app can connect to an external GPS or NMEA data stream using a serial port, USB serial device, Bluetooth or WiFi (TCP/IP or UDP).
It can also connect to the MacOS location service. However, we believe this only provides a static location from WiFi and is not suitable for real-time navigation. It is possible that in the future, there may be built-in GPS that works through the location service.
Note: the GPS connection is only used for real-time positioning and instrumentation. Direct transfer of marks, routes and tracks is not supported, because the interface requirements are so diverse. In order to transfer overlays, you can import or export the industry-standard GPX file format. Some GPSs (such as Garmin) have a mass storage mode, where you can directly copy GPX files to and from the GPS. Some GPS companies have their own software for programming the GPS.
Under GPS, Setup, click the Type of GPS Connection button.
You can connect a typical USB "puck" style GPS to the Mac, or use a USB to Serial adaptor to connect to an NMEA 0183 interface. Check with your USB device manufacturer for a driver for MacOS. If the manufacturer doesn't supply a MacOS driver, it is worth trying the Prolific Technology driver, as this is the chip used in many of these products.
To connect to a Bluetooth GPS or NMEA to bluetooth device, first close the app and go to the Bluetooth settings in the System Preferences app. Turn on the GPS and make it discoverable, then connect to it to create a pairing. Now in Memory-Map, go to GPS Settings. You need to select the Serial connection, because MacOS treats the Bluetooth device as a serial port. There will be two Bluetooth serial ports: one called "Bluetooth-incoming-port", which is typically NOT the one you want. The other may be called something like "Bluetooth<name>SPP", and this is the one you want.
The app can connect to a specific IP address and port number using TCP/IP, and is compatible with most NMEA to Wifi adaptors or AIS units with built-in WiFi. Refer to your device instructions to set up the WiFi network and determine the IP address and port number that you want to listen to.
The app processes most NMEA sentences commonly used in marine instrumentation, such as water depth, boat speed, wind speed and direction. A Professional license is required for these features. It can display any of this data on the Navigation data screen. You will need to customize the Navigation data screen to select the information. The app will also output the Autopilot RMB sentence if you are following a route or navigating to a waypoint.
If connected to a DSC equipped marine radio, the app will display the location of DSC position reports and DSC Distress signals, as a mark on the screen. It also sends a system Notification when a distress signal is received.
AIS is a powerful system for avoiding collision at sea that works by radio transponders on commercial ships. See the next page for details.
The app can replay raw NMEA data stored in a txt file. When the replay reaches the end of the file, it automatically restarts at the beginning.