[time-nuts] Making a Raspberry Pi NTP server without soldering

Hal Murray hmurray at megapathdsl.net
Tue Oct 22 18:48:48 UTC 2013


albertson.chris at gmail.com said:
> How the MAC connects is kind of like worrying if the chrome platting in that
> little hook on your tape measure has a well controlled plating thickness.
> Yes of course it matters, just not enough to worry about because all the
> other error sources are much larger. 

I think that's misleading.  USB is polled.  That adds a layer of jitter.

There are probably some systematic errors too.  When you send a packet, it 
leaves synchronized with the USB clock.  The return packet will also be 
synchronized with that clock so the return network time will be rounded up to 
the next clock tick with no jitter.

It would be interesting to see if we can measure it.

Besides, this is time-nuts.  We pay attention to that sort of detail.

But I agree that if all you are interested in is having reasonable time on 
nearby PCs a few ms won't matter.


-- 
These are my opinions.  I hate spam.






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