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If your device has a built-in GPS, your location is shown as a red circle with cross-hairs on the map. The center of the circle flashes to indicate when the position is updated, usually every second or two if there is good GPS reception. If the circle turns gray, GPS reception has been lost.
At any time when the GPS has a valid position, you can touch the GPS Lock  button at the bottom-right. This scrolls the map to show the position at the center of the screen. As you move the position is locked and the map scrolls automatically to keep the position in the same place on the screen (this effect is sometimes called a "moving map"). A dot in the GPS Lock button indicates that the GPS is currently locked and the map will move.
You can drag the map to re-locate the GPS position to one side, to show more of the map ahead in the direction you are traveling. Place the GPS icon anywhere you want on the screen, and as you move, the map will automatically scroll to keep the GPS icon in the same place on the screen.
As long as you don't drag the GPS position off the screen, it will remain locked at that screen location. If you drag the GPS location off the edge of the screen, GPS Lock mode is canceled.
If the GPS location is locked (moving-map mode), when the location moves off the edge of a map, then another map is automatically loaded.
The Home key, or the G key both act as a shortcut for GPS Lock.
If you are moving, you may also see a Velocity Vector. This is an arrow that shows your direction and speed of travel. The length of the vector is scaled to show where you will be if you maintain the same speed and heading for 5 minutes. You can change the scale in minutes in GPS settings.
Connecting an external GPS
If your device does not have an internal GPS (eg, iPod Touch or iPad with WiFi only) there are some 3rd party GPSs that connect to the device by bluetooth and deliver position information to the app through the location service. No special settings in the app are required.
You can also connect to a NMEA 0183 data stream via a serial port, or a WiFi gateway. Use the Settings > GPS Settings > Data Connection button to configure the connection.
WiFi gateway devices available for marine instrumentation, and allow you to connect AIS, wind, depth and boat speed instruments. See Connecting to Marine Instrumentation.
On Windows, Mac and Linux, you can pair your system with a Bluetooth GPS. The GPS data is then available to Memory-Map as a virtual Serial port, and you connect to it using the Serial setting.
Next: Compass Heading
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