Re: Roughtly converting DOP to metric error

On 1 Mar, 14:47, speleo...@xxxxxxxxx wrote:
Hi,

My cave survey freeware connects to a GPS for surface tracking. When I
connect to a Bluetooth GPS, the GGA and GSA NMEA sentences provide
various flavors of DOP values (PDOP, HDOP, VDOP). How can I provide
users with a rough error value in meters (as most GPS units do) from
these unitless numbers?

Luc Le Blanchttp://www.speleo.qc.ca/Auriga

You can't :)
DOP is not an indicator of "error" or "accuracy".
Bad DOP does not always mean bad accuracy for example.
Moreover the "accuracy" should not consider only DOP:
Imagine to be indoor (very low signal, a lot of multipath ecc) but
with a good DOP: you may have a very bad accuracy even with a good
DOP... So your indication DOP-based will be wrong.
Unfortunately, if you have only NMEA sentences, you usually don't have
enough data to estimate the accuracy (that can be done internally to
the receiver as it have much more informations inside)
.

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