Periodic spike in offset for pps

Gary E. Miller gem at
Tue May 5 19:35:32 UTC 2020

Yo Doug!

On Tue, 5 May 2020 15:22:23 -0400
Doug Curtis via users <users at> wrote:

> > Adafruit gps hat - are you regularly (weekly, biweekly) downloading
> > the satellite ephemeris data from mediatek?
> I'm not familiar with that so I'll have to do some reading on it.

Should not be needed.  The receiver gets current ephemeris directly
from each sat on the 50bps link.

> The ntpviz server is a separate Centos 7 server in my rack on a
> different circuit.

Maybe that is the problem.  How does the data get to the ntpviz server?
NFS?  rsync?  It will be batched somehow.

> Because of this testing, each antenna is on a different
> side of the house (west, south, and east).

Common practice for comparing receivers is one antenna into a power
splitter, thence to all the receivers.

> This does start me
> wondering the cleaniness of my power at the house though.

Common to see A/C cycling in the data.  But I doubt your house has
multiple A/C zones.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 851 bytes
Desc: OpenPGP digital signature
URL: <>

More information about the users mailing list