Re: [gpsd-users] Controlling the gpsd update rate

[Gary E. Miller]

Yo Deven!

On Tue, 27 Feb 2018 17:20:25 -0800
Deven Hickingbotham <address@hidden> wrote:

> > BTW, recent reports on this list that some u-blox skip some fixes
> > at 10Hz. 
> 
> I'm still investigating this, but the reports would be consistent
> with your evaluation of the output files I sent you.

Cool.

> I searched the u-blox forum and they recommend turning off output on
> the interfaces you are not using and pare the remaining messages
> being sent to the bare minimum.  This would include reducing the
> frequency of certain messages like satellite position.

Yeah, but you dod not have much to cut.

> How does gpsd handle messages being sent a various frequencies?

When gpsd gets stuff, it passes it on.  gpsd does not care about
what or how fast.  You care you get a complete fix. you likely want just
UBX-NAV-PVT.

> Suppose lon/lat are sent at 10hz and satellite data every 5 seconds?

Fine.  But why do you care about the sats as long as you got PVT?

> Would epx and epy (which I assume are based on satellite data) be
> zero during the intervening 5 seconds or would they be the last
> calculated value?

Nah, gpsd does not make up data, it just passes on what it gets,
when it gets it.

And don't take epx/epy/etc seriously.


> If I allow gpsd to optimize the settings, does the optimization only 
> occur at startup?

Yup.

>  I am trying to understand what gpsd will do if I 
> later use gpsctl to change a setting.

Well, right now, that can  be flakey.  But the code tries to just pass
on what you sent.

> If gpsd only optimizes at 
> startup, then my subsequent change would not be overridden.

Correct.

> If it is 
> continually optimizing, then it might override my change.

Nope.

> Finally, if I use the -b option, does this mean gpsctl and commands
> sent to the Unix domain socket will not work?

They may not work even with -b.  :-)

You are in an area that has been long neglected and I'm discovering bit
rot.

The common approach is to use u-center to set your, then run gpsd with -b.
I'd eventually like to replace u-center, not gonna happen soon.

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

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