[ntp:questions] Strange NTP problem on AMD Geode LX cards.

Unruh unruh-spam at physics.ubc.ca
Sat Oct 3 22:44:14 UTC 2009


John Hasler <jhasler at newsguy.com> writes:

>Unruh writes:
>> it has nothing to do with making the clock better-- it makes it
>> worse. It is just trying to use a loophole in the radiation emission
>> regulations.

>It isn't a loophole.  While it doesn't reduce the total power radiated
>it does reduce the interference with radio services which is the goal of

Well, no, it increases the interference over most of the band, and
reduces it for the specific clock frequency. This is done because it is
"too expensive" to shield the machine to eliminate the radiation.    

>the regulations.  I also don't see that it would make the clock worse.
>The "random" frequency modulation comes from a cycling PRNG and will
>average out to zero over a fairly short period.

That jitter added to the clock means that one is adding noise and thus
errors to every clock reading. That this averages out over a while makes
little difference since one tends to read the clock one reading at a
time, not averaged over 10 or 1000 readings. 

>-- 
>John Hasler 
>jhasler at newsguy.com
>Dancing Horse Hill
>Elmwood, WI USA




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