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Re: [gpsd-users] GPSD : Get vertical and horizontal accuracy (Vacc and H
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From: |
Gary E. Miller |
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Subject: |
Re: [gpsd-users] GPSD : Get vertical and horizontal accuracy (Vacc and Hacc) |
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Date: |
Mon, 17 Jun 2019 10:40:59 -0700 |
Yo Krishna!
On Mon, 17 Jun 2019 11:58:38 +0530
"Krishna" <address@hidden> wrote:
> Please provide more information on eph and epv fields. Any web
> documentation/link is helpful.
RTFM: "man gpsd_json".
That is overly confident about eph and epv. Since u-blox does not
document those values, no one really knows what they are.
Use them only as a vague "goodness" indicator. Use them with more
than a grain of salt.
> Our customer is using algorithm which
> uses NAV_POSLLH parameters for processing. Whether these fields
> internally derived by POSLLH UBX command?
Then you answer your own question with the source (driver_ubx):
> From the GPSD source code,
> I understand that "display_nav_sol" in UBX_NAV_SOL case updates the
> eph and epv fields. Whether my understanding is correct?
Yes, and also UBX-NAV-POSLLH, and others.
I would suggest you totally ignore eph, except for antenna tuning.
Better, but still marginal, use epx and epy.
RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
address@hidden Tel:+1 541 382 8588
Veritas liberabit vos. -- Quid est veritas?
"If you can’t measure it, you can’t improve it." - Lord Kelvin
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