I’m not that conversant with GPS as I should be, but I do know PLS now use GPS with their Total Base Stations, and it when tied to a nearby reference may also provide mm to cm resolution.
GPS kept changing so much in the 90s that PLSs couldn;t keep up with the changes, ...$5k min per shot of equipment, then 6 mo to 2yrs later it was out of date. It’s stabilized quite a bit now, but unfortunately, I haven’t had access to a good PLS update on the technology in about a decade. The professionals I work with, though, do use it daily and their flavor of GPS is quite a bit more rigorous than the consumer flavor on your SUV.
You said — I’m not that conversant with GPS as I should be, but I do know PLS now use GPS with their Total Base Stations, and it when tied to a nearby reference may also provide mm to cm resolution.
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Yeah, I’ve tried to indicate in what I’ve said, so far, that one can achieve precise positions through expensive equipment, the time to do it, and the processing afterwards (after the measurements) to make it precise (with computers/computing algorithms).
So, yes, you can get it quite precise...
But, what I was trying to show is that you can’t do it for an application such as crop circles. That’s a different story, as by the time you made all those precise measurements, you would barely be beginning on your crop circle and the day would be over... LOL...
I haven’t tried to mislead anyone on that. And also, a person could spend, as I said, $500 or more and still not achieve any better accuracy than a possible 30-foot variance, from one side to the other, even while standing still. For huge volume of GPS equipment out there, that is sold in mass, a 30-foot error is no big deal and makes no difference at all to the buyer.
I’m going to be getting one of those models that sells for about $400 and will do a fine job by me, but I’m not fooling myself into thinking that I’m going to get any better accuracy with it than what I said. :-)
My current model ties into my computer and has WAAS and acquires as many satellites as possible and is extremely accurate for its price range. It’s about a $200 model. I’ve used it quite well to get my speedometer accurate, at various speeds and it works great that way. “Speed” in an automobile works great with GPS, because you can average it over a period of time, if you have a computer program which will take the signals and process them for you while you’re moving along. In that application, acquiring speed while traveling at freeway speeds, the 30-foot errors can be averaged out and computed out of the situation that you’re in.