✘24 hour data for --disable-kernel-pll

Gary E. Miller gem at rellim.com
Thu Sep 29 21:45:18 UTC 2016


Yo All!

Below are the 24 hour results for --disable-kernel-pll on a RasPi 3
with Uputronics HAT.

With --disable-kernel-pll

       Local Clock      Local Clock  Local Clock    PPS         PPS
Poll  Freq Offset 90%  Jitter 90%   Stability 90%  Offset 90%  Jitter 90%
1          1.36 ppm       0.75µs      0.94 ppt       10.18µs    0.98µs

Normal:

      Local Clock      Local Clock  Local Clock    PPS         PPS
Poll  Freq Offset 90%  Jitter 90%   Stability 90%  Offset 90%  Jitter 90%
1          1.1  ppm       0.43µs      2.3  ppt        1.6 µs     0.34µs

The --disable-kernel-pll is worse in every measurement, except Local
Clock Stability.  Over 6x worse in PPS Offset, an important metric.
The grapsh also show that the local clock is more heavily damped with
--disable-kernel-ppl, not really a good thing.  The damping is confirmed
by Daniels quick comparision of the kernel and ntpd PLLs.

So, a good experiment, but disappointing results.

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