[time-nuts] Re: When did computer clocks get so bad?

[James Perkins]

My Dad who taught Electrical Engineering told me that when parts are sold
in different quality grades (like resistors or in this case, crystals),
that the parts that meet the highest spec are sold for a high price, then
the next highest quality spec parts are sold for less, and so on. So your
typical 30ppm computer chip will probably have a bias that is either about
+25ppm or about -25ppm, but definitely NOT likely to be in the range -10ppm
to +10ppm.

Cheers,
James

On Wed, Sep 29, 2021 at 1:10 PM Alec Teal <alec at unifiedmathematics.com>
wrote:

> Hi there,
>
> I have a question and I cannot think of anyone better to ask, for a
> project we need to time some things which are connected to a computer,
> using NTP and later using a GPS over bluetooth serial ports, we have
> discovered that computer clocks are terrible
>
> If you remove a linear drift (for example assuming it ticks at 1.00026
> seconds per second) it gets less terrible, and Linux can do this but it
> is clear that the computer clock doesn't expose this coefficient to the
> OS to let it compensate, it must be found (eg through NTP) - any ideas why?
>
>
> But more concretely, my watch is actually pretty good, it's off by < 3
> seconds and hasn't been set probably this year (I don't tend to bother
> with DST stuff, not for any reason just never get round to it) - when I
> was growing up and even now wall-clocks are not so terrible that I have
> to fix them (or NTP does with computers) very routinely.
>
> My theory is that super cheap crappy quartz clocks are now used in
> things which can be reasonably expected to be online most of the time,
> and thus use NTP - my watch cannot (and probably has temperature
> correction too? Given the varied temps it is exposed to) any truth to this?
>
> This is a very open ended question I understand, but if clocks were as
> terrible as I've found every computer and thing I've checked recently,
> why don't I remember setting wall clocks easily once a week?
>
>
> Alec
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-- 
James Perkins <james at loowit.net>  KN1X  www.loowit.net/~james
2030 W 28th Ave, Eugene OR 97405       +1.971.344.3969 mobile
Alternate email: <opalmirror at gmail.com>