Re: DBT sentences

[Gary E. Miller]

Yo Владимир!

On Wed, 16 Jun 2021 23:45:48 +0300
Владимир Калачихин <v.kalachikhin@gmail.com> wrote:

> 16.06.2021 23:04, Gary E. Miller пишет:
> > Your guess is as good as mine.  
> 
> Then my abstract:
> If the device did not send a time -- the epoch lasts forever. So 
> echosounder data will be actual any time on POLL request.

Maybe, maybe not.  For now gpsd assumes DBT data is in the same epoch
as the TPV before it.  It comes on the same serial port as the GNSS
data, so considered part of the same "device".   So as long as you have
a fix, you have DBT time.

If the DBT time is on a different device than the GNSS, well, then you
will find bugs.

> If the device sent some types of data simultaneously -- all of the
> types sets to empty with a new epoch. So echosounder data will be
> mostly unavailable to POLL request if this data appears on the epoch
> ends.

I would say most data is never available to POLL.  DBT follows the
same availability rules as the TPV from the same serial port (device).

> As result tcp data sources cannot be read by ?POLL; and must as 
> ?WATCH={"enable":true,"json":true}; if you want to see not only
> coordinates.

That is overly broad considering the universe of possibilities.  I would
just say that POLL is a PITA.

RGDS
GARY
---------------------------------------------------------------------------
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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