Using GPS

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 grey, GPS reception has been lost. The estimated accuracy of the GPS position is displayed on the Flip-side data page, accessed by touching the -> button on the toolbar.

At any time when the GPS has a valid position, you can touch the GPS Lock (cross-hairs icon) button on the toolbar. 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. You can drag the map to re-locate the GPS position to one side, to show more of the map ahead. As long as you don't drag the GPS position off the screen, it will remain locked at that screen location. If you move off the edge of a map, another map is automatically loaded.

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 by touching the green Settings button on the Flip side page, and selecting GPS settings.

Note, however, that the iPhone's GPS is optimized for car use, and it does not indicate motion well at slow speeds. If you are on foot, you may need to walk at a brisk pace for 50 yards or so before the iPhone's GPS indicates any motion at all. This is a limitation of the iPhone and not something we can overcome in the application. Once you are moving, even at slow speed, the application uses position averaging to estimate speed and direction. This means that at slow speeds, the velocity vector will lag behind changes in speed and direction. You can change the averaging time in the GPS settings.

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