[ntp:questions] A question

Unruh unruh-spam at physics.ubc.ca
Thu May 1 04:18:45 UTC 2008


"Bruno Cocciaro" <b.cocciaro at comeg.it> writes:

>"Hal Murray" <hal-usenet at ip-64-139-1-69.sjc.megapath.net> wrote in message
>news:pZOdnYCQicMrLoXVnZ2dnUVZ_tninZ2d at megapath.net...

>> If you are happy with binary results (rather than a string)
>> you could use NTP.  (Don't forget to consider time zones.)

>Yes, binary results may be good. But I am not able to get this result. I
>installed any progs, for example Dimension 4, which connect to any server
>and syncronize my pc clock, but this is not what I want.
>My problem is this: I run a Labview program which repeat several
>measurements (for example 10^6 measurements, 0.1 sec for each one). Labview
>prog uses an internal clock which says each measurement is 0.100 s, but I

I suspect that the only clock they use is the computer clock. Ie, they do
not have any special onboard hardware clock. 

On Linux
date +"%s.%N"
will give the seconds and nanosecods since Jan1 1970. (well not really
since leap seconds are ignored)
But for your purposes unless you run the experiment across a leap second,
that does not matter. 

Windows is more difficult. There is undoubtedly some equivalent command.
But Windows does not time to better than about .1 sec anyway.


will give you the seconds since 
>need to know the instant at which prog performs the first measurement and I
>must check that after 10^6 mesurements 1000??.??? seconds was spent. I am
>not sure of the fidelity of the internal clock used by Labview. My idea was
>that the fastest way to control the fidelity of the internal clock is to add
>a little part in my prog where Labview ask to any server the time, for
>example by a TCP or by any other way.

>Thank you very much to any user answered.
>-- 
>Bruno Cocciaro
>--- Li portammo sull'orlo del baratro e ordinammo loro di volare.
>--- Resistevano. Volate, dicemmo. Continuavano a opporre resistenza.
>--- Li spingemmo oltre il bordo. E volarono. (G. Apollinaire)





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