Wrong sampling rate from Sound Input Read VI on Dell Latitude E6510

[Oleleo]

Hi,

When I receive data from the sound card with the Sound Input Read VI, the actual sampling rate is not equal to the sampling rate set in the Sound Input Configure VI. I estimate the sampling ratio by dividing the number of samples received by the difference between the first and the last t0 from Sound Input Read. For example, if the sampling rate is set to 7000 S/s, the actual sampling rate is around 6900 S/s. If the sampling rate is set to 7050 S/s, the actual sampling rate is around 7200.

This problem appears when the code is run on my Dell Latitude E6510 machine. When I run the same code on my Lenovo ThinkPad, the sampling rate is correct.

The Labview application I am developing is to be used to acquire data synchronously from several sources, including the sound card input. It is therefore important that the sampling rate is correct. If anybody has any idea about what may cause this problem, and a way to fix it, I would be grateful.

Ole

[TomAD]

Hi Ole.

This seems a little strange. The actual sample rate increases 300 when you increase the configured sample rate by 50? And moves from below actual to above? Have you tried the more "common" sampling rate of 11025Hz?

It might be an issue caused by the soundcard driver. Do you use the generic driver or the driver supplied from the manufactorer? The generic driver should be avoided here.

What device are you using to sample? Can you try the Express VI to verify the bahaviour here aswell? I have a E6510 here, so if none of the above helps you can upload a code snippet showing this behaviour and I will have a look.

-Tom

[Coq_Rouge]

It has been a trend the last years that sound card only support some sampling rates, not a range. You should refer to your sound card manual for this kind of information.  You should also be aware of that the NI sound interface is junk, and they do care about it either. Use the WaveIO interface instead See the link. But I am quite sure your problem is related to the sound card hardware not some NI driver issue

http://www.zeitnitz.de/Christian/waveio

[Oleleo]

Thanks for yous replies.

I found out that by increasing the sampling rate to 44100, the actual sampling rate became acceptable.

Ole