Electronic Compass Confusion? in GPS technology and devices Posted August 17, 2007 Not quite. A unit without an electronic compass has to assume that the unit is being held exactly in line with the direction of travel. If you're a bit lazy in holding the unit, and let it drift 15 degrees to the left or right, guess what? The arrow is going to be pointing 15 degrees off. This is the same problem with an EC - if you're a bit lazy and hold the unit at 15 deg from level, guess what? the arrow is not going to point in the correct direction. The only difference in function between an EC equipped unit and one without, is the EC unit can correctly display the GPS orientation while standing still. The non-EC unit has to move a few feet to get its bearing and update the display. Once that is done, the functionality of the two units is exactly the same. Your comment above is not quite correct. While moving, the non-EC unit doesn't care how you orient the unit to yourself, it reports the bearing based on your current position and the coordinates of where you are trying to go. You can hold the unit with the screen facing away from you and the bearing pointer will still point to the waypoint. Or try this, hold the unit flat in front of you like you were using the EC but with the EC turned off. Now slowly rotate the unit 360 deg as you walk toward the waypoint. The bearing pointer will keep pointing straight ahead to the waypoint, even if you are holding it 90 deg off. Some people seem to think the GPS uses the compass to calculate the bearing to the waypoint. The compass signal is used for display purposes only. Bearings are calculated solely from coordinate data. Once moving, I turn off the EC. For me it is hard to hold the unit level and clump through the woods.