[time-nuts] Survey plot as art.
Gary E. Miller
gem at rellim.com
Sun Jan 8 16:52:08 EST 2017
Yo All!
I just ran 24 scatter plots on 2 GPS with external antennas one inch apart.
pi2-5.png is an Adafruit GPS HAT with an MTK-3301. upuv2.png is an
Uputronics GPS HAT version 2, with a uBlox 8.
See attached. I'm not sure it sheds any light on this discussion...
There does appear to be a bit of correlation between the bigger random
walks in the graphs. And a whole lot of other things going on.
During that time, the Adafruit saw 6 to 12 sats and a constant TDOP of
0.82. The Uputronics reported seeing 4 to 20 sats and a TDOP from 0.42
to 32.6 and a mean of 0.786 and a SD of 0.668.
To bring this back to time-nuttery, when the TDOP hit 32.6 I can see a
2 micro Second spike in NTP jitter. So for that small period in time
my Raspberry Pi clock was more stable than my PPS.
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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: upuv2.png
Type: image/png
Size: 19623 bytes
Desc: not available
URL: <http://www.febo.com/pipermail/time-nuts/attachments/20170108/051ba89d/attachment-0002.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pi2-5.png
Type: image/png
Size: 18159 bytes
Desc: not available
URL: <http://www.febo.com/pipermail/time-nuts/attachments/20170108/051ba89d/attachment-0003.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 455 bytes
Desc: OpenPGP digital signature
URL: <http://www.febo.com/pipermail/time-nuts/attachments/20170108/051ba89d/attachment-0001.sig>
More information about the time-nuts
mailing list