[time-nuts] Holdover, RTC for Pi as NTP GPS source
David J Taylor
david-taylor at blueyonder.co.uk
Wed Nov 1 12:07:43 EDT 2017
From: Mark Sims
I have an analytical balance that reads down to micrograms. The weigh
chamber is surrounded by three layers of IR absorbing glass so that radiated
body heat does not induce convection currents in the air. I worked on a
balance that had nanogram resolution (mostly wishful thinking in that spec).
It operated in a vacuum. 30 bit mass-to-digital converters are rather
finicky beasties.
It does not take all that good of a temperature sensor to detect changes in
room temperature due to body heat (or fetching a beer from the fridge in the
next room). You are basically a 100 watt space heater... even larger for
the more corpulent folks.
==============================
Temperature is indeed the killer. My best Raspberry Pis for time-keeping
are RasPi-1 and RasPi-4, both of which are in an unheated cupboard not
exposed to sunlight, on the north side of the house with indoor patch GPS
antennas.
http://www.satsignal.eu/mrtg/performance_ntp.php
Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk
Twitter: @gm8arv
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