[time-nuts] Looking for advice to get a submillisecond setup

Hal Murray hmurray at megapathdsl.net
Fri Feb 20 02:36:56 EST 2015


jimlux at earthlink.net said:
> So really, it's a matter of finding a place to put your Garmin receiver and
> string a cable that's not too long to your *nix box running ntp.

The "place to put your Garmin receiver" may not be as simple as it sounds.

It needs a good view of the sky.  Roof is best, but a window may be good 
enough.

A machine room is unlikely to work, even if you have a good window.  Too much 
EMI.  An elevator control room may have similar problems.

I've thought about building a pair of boxes that would use standard CAT-5 
cables as an extender for this sort of thing.   4 pairs works nicely: power, 
TX, RX, PPS.
 


> People have done it with a Rpi, if you want to go that route.

The RPi has its Ethernet chip connected by USB so that adds a bit of fuzz.

I should try to measure that.


-- 
These are my opinions.  I hate spam.





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