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Re: [gpsd-dev] ✘SiRFstarV

From: Gary E. Miller
Subject: Re: [gpsd-dev] ✘SiRFstarV
Date: Mon, 11 Feb 2019 12:41:40 -0800

Yo William!

On Mon, 11 Feb 2019 07:31:50 +0100
William Smith <address@hidden> wrote:

> >Odd.  I assume you used gpsctl to flip from binary to NME and back?  
> Yes I switch using gpsctl -n / -d

And, as you say later, u-center.

> >I'll look for it.  Some ublox 8 get almost 30 sats.  The u-blox 9
> >even more since it is L1 and L2.  
> I am looking forward to getting a 9 series RTK unit from u-Blox.
> They are quite expensive, though, atm.

A ZED-F9P is only slightly more than a NEO-M8P.  Both are a bit
spendy by modern standards.

> >Works for me.  What GPS models did you try?  
> SAM-M8Q-0-10, a pcb mount variant with everything built into the
> antenna, which is 1.5 cm. (and sensitive, nonetheless)

I'm guessing still marginal indoors.  I find the xtra 20dB gain from
an external antenna helps a lot inside.

> >But what software in the VM?  Did it reconfigure the GPS?  
> uBlox Center, I think it is called. I don't know what it does. I
> may try to put a sniffer on the serial port.

They call it u-center.  Due to the way the u-blox mashes different
config optons together, u-center needs to do some odd things in the
background to work.  For example, some messages allow yu to change 10
different settings.  If you only want to change on, then u-center has
to read you receiver type and version, read the existing config, patch
in the new change, the write the new message back.

Not well documented, and has some hidden heuristics.

> gpsd seems to support uBlox very well.

But a lot options it does not...

> The version I use is always development HEAD. I fetch from
> git daily.


> Attached here are the captures you asked for. (of the SirfStar4
> module)


Your binary file is not binary, it is NMEA: royaltek_reb-16_binary.log

It is also about 20% zeros.  One fix is often just 3 sentences:


That hits a known NMEA bug, setting fix mode with limited NMEA data.

It also shows you GPS is not where "gpsctl -n" tries to get it.  No

And shows me your GPS is not set like you think it is.  NMEA, not
the binary you thought.

You other file, royaltek_reb-16.log, is a very similar NMEA.  Also
not how "gpsd -n" tries to set things up.  At least not 20% zeros...

So, more new questions than answers:
    why do you think you are in binary mode when you are not?
    why all those zeros?
    why is the NMEA mode not sending all the right sentences?

Yes, but not the version confirmations I asked for:

> > And confirm your gpsd, xgps, cgps versions for me.

Easy to do:

    address@hidden ~ $ gpspipe -V
    gpspipe: 3.19-dev (revision dev-3.19a-281-g6dd78a6e)
    address@hidden ~ $ cgps -V
    cgps: 3.19-dev (revision dev-3.19a-281-g6dd78a6e)
    address@hidden ~ $ gpsd -V
    gpsd: 3.19-dev (revision dev-3.19a-281-g6dd78a6e)
    address@hidden ~ $ xgps -V
    xgps: Version 3.19-dev

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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