GPS Question

[Hans]

In another thread, a fellow asked:

> 2. Since the points stored in memory were
> entered while the error was in place, is
> it a good idea to try to locate those spots
> and re-enter the way points?

It is a good idea to check them. Some, maybe even most, will probably be spot-on accurate, but others will be off by varying amounts.

There is a bit of a misconception, I think, in the amount of change we will find in our previous waypoints. In the "SA Era" the GPS product to consumers *could* be off by as much as 100 meters. That doesn't mean that it *was* off by that much -- only that it could have been. Based on a lot of usage of GPS in fishing, hunting, and automotive applications, my guess is that most of the time the DoD-introduced errors were far less than the maximum allowed.

Naturally we can now have a lot more confidence in our new spots, but I don't think we'll find that a lot of our old spots were that far off either.

Hans

[Hans]

Turns out someone has already done a comparison.

There's a web site at -

#####://#####.igeb.gov/sa/diagram.shtml

Spots were taken every 30 seconds for 12 hours.

The plots show that SA causes 95% of the points to fall within a radius of 60.7 yards.

Without SA, 95% of the points fall within a radius of 7.9 yards, or about the length of a nice walleye boat.

Hans
--
"There is nothing; absolutely nothing; half so much worth doing,
as simply messing about in boats." :-)

[Hans]

It appears that the list software farkles URLs.

Here is that site address again, just eliminate the spaces.

h t t p : / /w w w.igeb.gov/sa/diagram.shtml

Hans
--
"There is nothing; absolutely nothing; half so much worth doing,
as simply messing about in boats." :-)