cyclones30 - 3/14/2023 15:50
ljadx160 - 3/14/2023 14:31 That plus or minus 6” is a short term pass to pass accuracy. It’s not that associated with absolute accuracy, either in actual position or repeatability. Yes, when you mark an intake it records a lat and long. To your example, it might be several feet off an hour later or the next year. But it’s not like keeps getting worse over time. It should always be within a few ft and randomly may be spot on.
With SF1 and even more-so WAAS, it's drifting all the time slowly over time. But still stays centered as a whole.
Think of a tire swing hanging from a branch blowing in a random wind. If you took a picture or location of that tire above the ground at any one time it'll be close to the next time you looked at it whether it's today, tomorrow or next year. But it could be a few inches or few feet away in really any direction. Or you could luck into it being right back in the same spot that one time again. GPS drift isn't as fast as a tire swing of course, but shows the coming back to center nature but you never know when that is as the rover. If you drop a flag on the monitor when you're as much drifted west as it goes and next year you come back and it's as far drifted east as it happens to go, you could be 5' off.
Or think of it like giving a 3 year old kid a crayon and a sheet of paper. Tell them to just start drawing all over the page, can't lift off the paper, and you'll tell them when to stop. That random mess is what the drift looks like, you just don't know where you are and when on that timeline with the lower end GPS signals. You might be near the middle or you could be near the corner