Originally Posted by
Iride01
There are also tricks that programmers use with automotive type GPS's. It's expected that automobiles will stay on the road. So though bad signal reception might show your position 50 feet off in the trees, the software says "hey, this is a car going 70 mph. It must be on this road over here that's going the same general direction". So instead of showing you where the GPS resolved positition is, they show you on the road. So your perception is that automobile gps are better.
As a hiker, I see this sometimes. Get off the highway, follow some local road a while, then a faint dirt road to the trailhead. The car GPS shows me on the paved road for a few hundred yards, then it accepts that I really have left the road, and shows my actual position.
Side note: I have a cheap electronic bathroom scale. It's
also got some cheat programming in it. If I step off and back on, I get the same number. If I step off, pick up a half pound glass of water, and step back on, I get the same number.
I suspect in both cases it's that the sensors aren't perfect and the data is noisy and this is how people thought to deal with it and provide a consistent user experience.