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Re: release?
From: |
Gary E. Miller |
Subject: |
Re: release? |
Date: |
Sun, 1 Jan 2023 19:14:45 -0800 |
Yo Fred!
Sounds like you have some ideas. I look forward to the results of your
looking. But too late for this release.
On Sun, 1 Jan 2023 19:08:43 -0800 (PST)
Fred Wright <fw@fwright.net> wrote:
> On Sat, 31 Dec 2022, Gary E. Miller wrote:
> > On Sat, 31 Dec 2022 00:57:17 -0800 (PST)
> > Fred Wright <fw@fwright.net> wrote:
> >
> >> I didn't see any issues with build/check on a wide variety of
> >> platforms. But the skyview spasticity is still present. It can be
> >> seen with cgps, xgps, or xgpsspeed (xgps being the most obvious).
> >> I'm using a uBlox M9N receiver with a multi-system antenna.
> >
> > That is because your GNSS is being spastic about sending sky data.
> > There is no right answer, short of fixing the receiver firmware.
>
> Nope. And I've attached a logfile (-Rw) to show that. If you look
> at it with ubxtool, you can see that numSvs only varies between 38
> and 39 during this interval, while the xgps display toggles at 1Hz
> between that and ~30 during that interval. It almost certainly
> relates to the alternate SKY reports with no satellites. I suspect
> that the only reason all the satellites don't come and go relates to
> the timing of building the display in the client vs. the list being
> cleared and rebuilt every second.
>
> If the intent is that SKY reports with no satellites are legitimate
> (just to report slightly changed DOP values), then all clients need
> to be fixed to retain the old satellite list when that happens, and
> this behavior needs to be clearly documented so that third-party
> programs can be fixed as well.
>
> The prRes behavior is another story. I started looking into this,
> but I don't have any more time tonight. The values are reported in
> both UBX-NAV-SAT and UBX-NAV-SIG, so my initial guess was an
> inconsistency between the two, with them fighting each other in the
> output reports. But the few cases I spot checked looked like they
> were consistent between the messages.
>
> The actual values of prRes are also "interesting". Although the
> quantity is nominally defined as signed, I don't see how a residual
> can possibly be negative. But many of the values reported by both
> ubxtool and xgps are negative, with some strange scaling between the
> two that also seems inconsistent with the definition (the doc says
> 0.1m units).
>
> > I do have some ideas for after the release to add a lot of latency
> > and reduce flicker. My guess is it will have to be an optionas the
> > extra latency will annoy many.
>
> I've also had some ideas on how to fix issues with GSV, which don't
> add much latency, but that isn't relevant here, or in any other case
> where the receiver provides single reports covering all satellites.
>
> >> With the 3.24 xgps (and the latest gpsd), both Sats Seen and Sats
> >> Used toggle between zero and values that are probably correct.
> >> With the current xgps (and still the latest gpsd), Sats Used is
> >> reasonably stable (varying a bit as one would expect; right now
> >> ~18), but Sats Seen toggles between two very different values
> >> (right now 32 vs. 40), where the larger is probably correct.
> >
> > You can thank NMEA 4.11 for that. It has to do with the way the
> > receiver dribbles out the sky data.
>
> Nope. This is a u-Blox receiver providing UBX binary messages (the
> gpsd default behavior), except in the gpsmon case.
>
> Fred Wright
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
gem@rellim.com Tel:+1 541 382 8588
Veritas liberabit vos. -- Quid est veritas?
"If you can't measure it, you can't improve it." - Lord Kelvin
pgpoU1u26TDb4.pgp
Description: OpenPGP digital signature
- Re: release?, Fred Wright, 2023/01/01
- Re: release?,
Gary E. Miller <=
- Re: release?, Greg Troxel, 2023/01/02
- Re: release?, Nick Taylor, 2023/01/03
- Re: release?, Gary E. Miller, 2023/01/03
- Re: release?, Gary E. Miller, 2023/01/05
- Re: release?, Fred Wright, 2023/01/05
- Re: release?, Gary E. Miller, 2023/01/06
- Re: release?, Fred Wright, 2023/01/06
- Re: release?, Gary E. Miller, 2023/01/06
- Re: release?, Gary E. Miller, 2023/01/06