On 9/6/19 19:45, Gary E. Miller wrote:
On Fri, 6 Sep 2019 14:56:26 +0200
Ellon Paiva <firstname.lastname@example.org> wrote:
Field 10, HDOP. Missing.
This was in purpose, as I am not really simulating localization
And yet you include accuracy estimates which are derived from the
DOPs, which are derived from the skyview.
My accuracy estimates come a covariance matrix from which I extract
the error ellipsoid and standard deviations used to fill the fields
of a GST sentence. I know that these fields are supposed to have
information derived from skyview, but I think skyview doesn't apply
If you are confident in your values, then put them in your data output.
Just be on the watch any unexpected behavior in gpsd dues to their
I think I could find a way to derive HDOP from the same covariance
matrix... but first I need to understand better the HDOP concept on
Easy "error = xDOP * Uere".
Where Uere is a variable broadcast by the GNSS system to tell the user
about how good the current signals are relative to optimal.
Current Uere is about 9.4. So right now, on one GNSS, I see
7.80288 m Xerr = 0.8 XDOP * 9.4
But there is no need for you to provide the DOP's if your error
estimates are "good". Sadly I never see "good" error estimates...
By the way, I tried to understand the "226 degrees east" problem, and
in fact I realized it's not a problem! In the sentence you mentioned
the lon/lat are expressed in "Degrees Decimal Minutes" as I
understood that's the way they should be described. So longitude
"226.381659556439,E" in fact means "2 degrees and 26.381659556439
minutes east". The same thing with the latitude:
"4850.432180742773,N" means "48 degrees and 50.432180742773 minutes
Uh, oh. My mistake, I read that too fast, you are correct. 226.38 is
And gpsd is not the gold standard, you likely want your psuedo NMEA
to work for most NMEA decoders.
In fact I would like it to work in gpsd because gpsd is already used
in our project. Indeed having it working with most NMEA decoders
would be a bonus, but we're not interested on that (as far as I know).
And to work with gpsd you just need to stay close to the spec and/or
common usage. Even though you data is clearly uniquely created.
I'm sure with a bit of work we can make the two parts work together.
When you have another set of NMEA output, send it along and we'll
both take a closer look at it.
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
email@example.com Tel:+1 541 382 8588
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"If you can't measure it, you can't improve it." - Lord Kelvin