Hal Murray <[email protected]>:
> You can use a Pi with GPS to monitor other systems, but the Ethernet on USB
> that limits the resolution of what you can measure. It's probably good
> enough for watching sites on the Internet and/or your ISP connection. It's
> probably not good enough if you are interested in the difference due to using
> the kernel PLL.
I'm planning to use the test farm to address that question. The idea
is: configure two Pi 3s identically, except that one ntpd build has
KERNEL_PLL disabled. Probably the easiest way to arrange this will also
be closest to the real-world case: benchmark refclock 20 against
28 being fed by gpsd.
Run them in paallel for a couple days after they stabilize, collecting
*mumble* statistics. Compare statistics to see if we can see evidence
of any accuracy gain above the noise floor.
The main reason I haven't tried this already (other than being swamped with
other tasks) is that I don't know what the value of *mumble* ought to be.
What statistics should we collect? What figure(s) of merit do we look
for after the test run?
I need a pretty detailed answer to this question before we can move forward
on this front. Please consider it carefully and bring the full weight of
your expertise to bear.
--
<a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>
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