Since EveryTrail has started showing elevation tracks, I've noticed an unusual behavior. When I turn on the GPS (Garmin Etrex Legend mounted on a bicycle), the elevation is usually high. This is not an EveryTrail problem, because I see these numbers on the GPS while I am riding. I just never noticed the pattern before.
I started this morning at what I think is 80 feet elevation, with the GPS reporting 150. After a few minutes of flat riding, the elevation came down where I expected it, and my morning commute ended at an elevation of about 30 feet, which I believe is correct for that end. In the afternoon, when I turned it on, the elevation was about 115 feet, and then as I rode, it settled down to what I think is the right number, and when I got home it was reading 80 feet, which I presume is close to correct.
Has anyone else noticed this? Can anyone explain it? One thought is that both ends of the trip are close to buildings, so I'm working with near-zenith satellites. I understand that this means inaccurate elevation, but I'm surprised that it seems to always be high, rather than random.
This is not a big deal, but I'd like to understand the GPS a little better.