Precise timings ?

Adriaan Renting renting at astron.nl
Wed Aug 31 09:28:16 CEST 2005


One of the limits of at least IBM compatible PC's is that in general they are not more accurate as about 1/64 th of a second if I recall correctly. I think this is the default tick size of the BIOS clock. Next to that the
BIOS clock itself doesn't need to be very accurate, I can easily drift like an hour a year.
Oh, and on top of that: If you are in a multi taksing operating system this complicates matters even further. Finally there's interrupts, as other posters pointed out.

This explains it very well:
http://www.beaglesoft.com/mainfaqclock.htm

There was a thread with the same question 'time.clock() problem under linux (precision=0.01s)' about a month ago.
I think it had some suggestion of using a soundcard sampling rate to get an accurate clock. I think that without an external calibrated device, you're not going to get any real accurate timing, precission isn't the same as accuracy.

Adriaan.




Adriaan Renting        | Email: renting at astron.nl
ASTRON                 | Phone: +31 521 595 200 (217 direct)
P.O. Box 2             | GSM:   +31 6 24 25 17 28
NL-7990 AA Dwingeloo   | FAX:   +31 521 597 332
The Netherlands        | Web: http://www.astron.nl/~renting/



More information about the Python-list mailing list