Re: Mode/Status not updated in shared mem mode

[Gary E. Miller]

Yo Владимир!

On Thu, 9 Jan 2025 01:46:14 +0300
Владимир Калачихин <v.kalachikhin@gmail.com> wrote:

> 08.01.2025 23:59, Gary E. Miller пишет:
> >> ?POLL is historical.  
> > 
> > Uh, no.  Works fine.  Some clients use it.  Usually single
> > shot clients.
> >   
> Sorry for my english.

Much better than my Russsian!

> Yes, ?POLL works well too in my proxy. This was originally created to 
> support ?POLL. But I mostly use ?WATCH now.

Agreed, ?WATCH is better.

> >> The main goal is user-defined lifetime for every
> >> value.  
> > 
> > Wow, every value?    
> 
>       'altHAE' => 20,
>       'altMSL' => 20,
>       'alt' => 20,
>       'lat' => 10,
>       'lon' => 10,
>       'track' => 10,
>       'heading' => 10,
>       'speed' => 5,
>       'errX' => 30,
>       'errY' => 30,
>       'errS' => 30,
>       'magtrack' => 10,
>       'magvar' => 3600,
>       'mheading' => 10,
>       'depth' => 5,
>       'wanglem' => 3,
>       'wangler' => 3,
>       'wanglet' => 3,
>       'wspeedr' => 3,
>       'wspeedt' => 3,
>       'time' => 10

Not all those come from your GNSS receiver.  The wind stuff comes
from sensors with usually no time stamp.

> 
> > Messages are timestamped, not individual data values. 
> > And in most GNSS cases, all values all change once per epoch.
> > 
> > So not giving you any new real information.  
> 
> GNSS, but not AIS. And GNSS and echosounder and windmeter epoch are
> not necessarily in phase.

Of course.  AIS has its own time stamps, and windmeter usually none.

> And any device can freeze, socket can die...

Of course.

> Therefore, if there is
> no data during the timeout by gpsd timestamp, the value is set to
> null.

Of course the real provlem is what is "the timeout"?  Some GNSS run at
20Hz or more.  Others at once a minute, once an hour, once a day.

So gpsd leaves "the timeout" to the client.  No way to know what the
client wants.

> I can do without the actual coordinates for 10 seconds, but
> only 5 without the actual speed. If the gpsd does not send new values
> within this time, the gpsdPROXY will send null to the client.

Which might confuse some clients.  Which is why gpsd leaves it up to
the user/client.

RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@rellim.com  Tel:+1 541 382 8588

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