Poor GPS signal
I run some trails in an area that does not have a good GPS signal. These are popular trails in Georgia North of Atlanta. I run with two buddies and we have tried just about every GPS app on Apple and Andriod phones as well as Apple and Garmin Watches. We know the distance of the trail because they are marked by the US Army, however, we get different readings every time and usually come up with about 20% less in distance than the actual trail. Any suggestions?