Re: [gpsd-users] How do you calculate position uncertainty?

[Tomalak Geret'kal]

On 16/04/2012 19:42, Irene Stefani wrote:
> Hi,
> could you explain me what exactly indicate epy and epx 
> (latitude and longitude position uncertainty)?
> is this a standard deviation of the error in estimated 
> receiver position? do you obtain it from HDOP and PDOP?and 
> how?
>
> Thanks a lot,
>
> Irene
Hi Irene

Lines 745-753 of libgps_core.c 
(http://git.savannah.gnu.org/cgit/gpsd.git/tree/libgpsd_core.c#n745) 
suggest that epx, epy and epv are functions of multiplying 
the relevant DOP value by some constant uncertainty values 
(http://git.savannah.gnu.org/cgit/gpsd.git/tree/libgpsd_core.c#n673).

Hope that helps

Tom