Different GPS units/different coordinates

[The Mad Hikers]

Do many people find that their GPS units are off by a significant distance verus the posted coordinates of a cache? I know that some of it has to do with the number of satelites aquired but the hider of the cache would have the same access to the sky right?

[+Renegade Knight]

Different time of day. Different atmospheric distortion. Different GPS. Different etc.

[Swagger]

It depends on a lot of things. What do you consider to be a "significant distance"?

 

As far as the satellites go, the hider would have the same access to the sky, but the satellites aren't geostationary. You could have a solid lock in a canyon at 1pm and at 2pm you could get nothing. It depends on where the sats are at the time.

 

WAAS can also change the accuracy of a given GPSr.

 

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Pehmva!

 

Random quote:

[The Mad Hikers]

I though the time of day would have something to do with it but I never knew WAAS would throw it off also. Thanks for the information. I guess it would take the fun out of it if you went directly to the cache.

[Kerry.]

Knowing what that

quote:

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significant distance

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might be is the key to any meaningfull reply.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[The Mad Hikers]

I mean approximately 100 feet or so. Does that count as significant?

[+fizzymagic]

quote:

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Originally posted by The Mad Hikers:

I mean approximately 100 feet or so. Does that count as significant?

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Yes. My GPS generally puts me within 30 feet or so of the correct location with reasonable satellite coverage.

 

BTW, WAAS corrections will not "throw it off." If you have them, then you should be more accurate; if you don't, then the GPS accuracy will be less. That's what the earlier poster meant.

[Kerry.]

100 feet under normal conditions maybe/maybe not.

 

Under normal conditions that's a little more than what the system has been generally providing of late.

 

Less than 30 feet is generally around the norm but keep in mind that the system is spec'd at less than 13m (42 feet) 95% of the time under average conditions and 36m (118 feet) 95% of the time under worst case scenario.

 

For your location (Secane, PA) the 100 odd foot mark can also close to the difference between NAD27 & WGS84 (about 108 feet). So there might be some datum issue?

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go