[time-nuts] Re: Accuracy of a sound card

[Alberto di Bene]

   I have measured the accuracy of the time base of my M-Audio Delta 44
   sound card with the tolerance (and the accuracy) of 2.5 ppm
   I modified my program TCube for a sampling rate of 96 kHz, and set it
   for 40 kHz output.
   I connected the output to my 5328B (whose time base is driven by my
   Z3801A), and set it for a frequency measurement period of 10s.
   This gives a frequency resolution of 0.1 Hz
   Measuring 40 kHz with a resolution of 0.1 Hz means that the error is
   at maximum 2.5 ppm, as the accuracy of the Z3801A is orders of
   magnitude better.
   What I measured was 40002.7 Hz that translates into an error of 67.5
   +- 2.5 ppm
   When I did the measurement, the PC had been switched on since abt. one
   hour.
   Will repeat that both after ten hours of power on, and just after
   switching on the PC.
   73  Alberto  I2PHD
   P.S. Let me please test how this reflector behaves when sending HTML
   messages... I have noticed a strange behavior in the past... it
   insists on reformatting
   the HTML message at its will...
   Here following there should be an image... let's see if it shows up
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