NMEA sentences; other GNSS

[Gary E. Miller]

Yo Paul!

Maybe best asked one gpsd-users at nongnu.org?


On Fri, 14 Jun 2019 16:24:49 -0700
Paul Theodoropoulos <paul at anastrophe.com> wrote:

> Two quickie questions, as I've read an assortment of conflicting
> things on our old friend the Internet:

Hehehe.

> 1. What are the minimum/desireable NMEA sentences for a GPS receiver
> to send gpsd for timeservice?

Minimum:

$GPZDA for the year.
$GPRMC for the date and time.

gpsd when asked, will set u-blox to:

$GPGBS
$GPGGA
$GPGSA
$GPGST
$GPGSV
$GPRMC
$GPVTG
$GPZDA


> 2. On the ublox neo-M8T, it supports GNSS:
> 
> GPS
> SBAS
> Galileo
> BeiDou
> IMES
> QZSS
> GLONASS

Tests show that just GPS is usually best for the PPS.  YMMV.  Easy to test.

> I know that IMES and QZSS are specific to Japan, so definitely not
> needed 

IMES is indoor "GPS".  Do not use that!

> Is there any value in having anything other than just GPS enabled,
> for a stationary timeserver? Does SBAS help at all?

SBAS corrections help, but raning from SBAS hurts.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at 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
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