Amazing project, great write-up. Would love to see a temperature graph as well! I'm wondering how good the PID controller here is working.

For future improvements, a cheap but effective win might be to put a temperature sensor on the oscillator (or two or three in various places). And use that to drive the PID loop.

Even if just experimental & not long term, it would be nice to have data on how strong the correlation is between the cpu & oscillator temperatures. To see their difference and how much that changes over time. Another graph! CPU vs txco (vs ambient?) temperatures over time.

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auspiv 11 hours ago | parent | next [-]

I for sure thought I included one, updating with that in a min!

Others have mentioned the temperature compensation. I've done it and it sounds like I should do that for the next writeup. A simple DS18B20 close to the Pi produces reasonable results.

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Kerbonut 18 hours ago | parent | prev [-]

> put a temperature sensor on the oscillator

At that point, couldn't we just use the temperature value to compensate for the drift?

	▲	HPsquared 16 hours ago \| parent [-]
		You can do that as well, but (in theory) the correction will be smaller than it otherwise would need to be if the temperature is regulated within a narrower range.