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Re: [Ntp] Temperature Compensation for NTP?

Hal Murray <hmurray@megapathdsl.net> Tue, 08 December 2020 23:32 UTC

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From: Hal Murray <hmurray@megapathdsl.net>
In-Reply-To: Message from Harlan Stenn <stenn@nwtime.org> of "Tue, 08 Dec 2020 13:50:52 PST." <d406413e-c539-cb74-daf4-5298a8a1db83@nwtime.org>
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Subject: Re: [Ntp] Temperature Compensation for NTP?
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Harlan Stenn said:
>, the behavior will be different and there will be train wrecks.

One man's train wreck is another man's innovation.

How do I decide if I'm allowed to implement a feature/idea that isn't 
mentioned in the RFC?  Temperature compensation is the obvious example.


> NTP is all about a defined impulse response.

Then an RFC should describe the constraints, not bury it as an obscure 
parameter hidden deep inside an algorithm.


kurt@roeckx.be said:
> I think defining NTP as a impulse response is the wrong approach. It's an
> implementation detail. If other systems use different algorithms, it should
> only have an effect on the uncertainty. If it causes big problems, it's an
> implementation problem. 

Not quite.  It's easy to get problems when chaining PLLs.  I don't understand 
it well enough to explain and I don't have a handy reference.

The typical problem is that somebody tweaks a time constant so his system 
recovers faster, then months later something crazy happens when triggered by 
the right input data.


-- 
These are my opinions.  I hate spam.

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