how can make a accurate measurement of THD With PCI-6052

[waltersz]

I want to use pci-6052 to test the audio signal of MP3 Audio output. And i want to get the THD Plus noise of the signal. But i find that the measurement of the THD VI is not accurate compared with the result measured by specific Audio analyzer such as Panasonic ,Agilent. So my question is how can make a accurate measurement of THD With PCI-6052 . I have also tried PCI-4472 and the result is not so good also. Hope for your suggestion !

[Salvador_Santolucito]

Hi,

It would be helpful if you could post the code you are using to do the measurement and analysis.

My suggestions would be:
1) Set the range of the board to be as close to the range of the signal you are measuring (do not use a range that is too large).
2) Use the largest possible sampling rate.
3) Make sure you are using a shielded connector block and cable.

Is the measured signal inacurate? Or is the analysis inaccurate?

-Sal