On Thu, 26 Aug 2004 23:21:15 GMT, "Arty Facting"
wrote:

There is an interesting test that can be done with some units to visualise
variabilities

The test is even better if an alternative power supply is rigged to the unit

leave the unit in one spot - don't move it, not even an inch. Then let it
run for as long as you can. A couple of hours or even overnight

Then look at the track it has traced

Ideally all the points should cluster around a single co-ord

Chances are there will be a fair bit of movement as seen in the tracks
recorded and displayed and this, remember, is for a stationary unit

I mention this merely to retain some sense of rationality and
proportionality as I have met people that are under the impression that
there are no such things as error bounds.


Indeed. All my statements are based on measurements. Before SA was
turned off, several university web sites kept continuous plots of the
wandering. Now you can do it with the internal plot on just about any
GPS.
Artio
(formerly das Bagal or even Bagal)

"Rodney Myrvaagnes" wrote in message
.. .
On Thu, 26 Aug 2004 17:47:12 GMT, "Arty Facting"
wrote:

Hi

I don't know if you know so I'll mention it anyway

Most GPS units have a measurement accuracy or inaccuracy.

It would be fine if it was consistent day-in & day-out, but it is not

It varies with signal and satellite availability and also with weather
conditions.

The reason I mention this is because you may return to bang the same
co-ords
as on the GPS and be up to 30 yards from what you wanted to find. That
being said & writ GPS units are mega-phun!

Before WAAS and while selective availability was in effect, it could
wander as far as 400 feet. However, in recent years I have found about
2 meters to be the practical limit. I check when tied up in the marina
slip occasionally.

There is no way you could come back to the wrong gravestone in an
ordinary cemetary.


Rodney Myrvaagnes NYC


We have achieved faith-based science,
faith-based economics, faith-based law
enforcement, and faith-based missile
defense.
What's next? Faith-based air traffic control?


Rodney Myrvaagnes NYC


We have achieved faith-based science,
faith-based economics, faith-based law
enforcement, and faith-based missile
defense.
What's next? Faith-based air traffic control?