Temperature Controlled rasPi 3B

[Gary E. Miller]

Yo Achim!

On Wed, 26 Apr 2017 21:43:03 +0200
Achim Gratz via devel <devel at ntpsec.org> wrote:

> Gary E. Miller via devel writes:
> > Cool.  Did you use ntpheat?   
> 
> No, I've simply extended the Perl script that logs all PPS timestamps
> (this also ensures that all the measurements are aligned with the
> loopstats).

Hmm, no perl in NTPsec anymore.  Care to submit that for contrib/ ?

> > ntpheatusb already has a full PID controller.  Did you look at
> > that?  
> 
> No again, I avoid looking at Python as much as possible.

Well, the algorithm is still the same in Perl and Python.  If you get
it done, please submit that too for contrib/

> > If yu do so, could you send us patches for ntpheat?  
> 
> See above.  It's really nothing spectactular, so I don't expect it
> will be difficult to translate, however.

Since Python annoys you, I'm sure others would like to see your perl.

> > I found that keeping the CPU chip temp stable was less important
> > that\n keeping ambient stable.  The XTAL is on the other side of
> > the PCB from the CPU.  
> 
> I know.  I have described the exact setup in excruciationg detail to
> you before, so I'm not going to repeat why the CPU temperature can be
> used as a proxy for the ambient in that case.

And I guess we'l have to disagree on how well that works.

>  Remember that this is
> about getting the best possible performance out of the rasPi for
> exactly zero cost above the rasPi and GPS itself.

Yup.  And even better when you send us the tools to put in contrib/
so others can replicate.

> > I also found adding a fan to the box evened out the temps between
> > PCB top and bottom better.  
> 
> I have salvaged a few nice copper heatsinks from servers that were
> thrown out at work that I will use later on for a better version of
> the ovenized NTP server.  I already got some temp/humidity/pressure
> sensors so I can check the actual temperatures and other environmental
> influences.  It will most likely not make any difference for the
> clients, so it's really just a game to see how far I can push this.

Yeah, the frequency jitter keeps getting beter, but not the time jitter.

> > How is the predicted frequency offset calculated?  Could that be
> > patched into ntpviz?  
> 
> I believe I've detailed the aging equations to you before.  Teasing
> out the five model variables from the data requires a bit of care,
> but the fit is easily done in gnuplot.

Yes, I remember your descriptions, what I'm asking for is code.  reuseable
code.

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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