[time-nuts] Holdover, RTC for Pi as NTP GPS source

David C. Partridge david.partridge at perdrix.co.uk
Wed Nov 1 12:44:09 EDT 2017

? RasPi-4? Not released until 2019 AFAIK ...  I have RasPi-3

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of David J Taylor via time-nuts
Sent: 01 November 2017 16:08
To: time-nuts at febo.com
Subject: Re: [time-nuts] Holdover, RTC for Pi as NTP GPS source

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.


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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