I need to know how to calculate precission of a VI

[lele]

Hello,

I'm developing a system to measure THD of an audio signal.

I'm thinking of using "Harmonic Distortion Analyses 1Chan.vi" that I have found on the examples of my LV7 base package

The problem is that is very important for me to know the precission of the algorithm calcaulation... I have no idea in how calculate the uncertainty of that "digital" measure...

Can anybody help me?

LAURA

CESVAinstruments

Message Edited by Support on 04-19-2006 09:03 AM

[Henrik_Volkers]

Good question 🙂

In the (more or less) analog world, you would provide a known signal and read the result. Do some calibration and you could get a good guess on your precision. (However, if you talk to guys from NIST,PTB,... there is a lot more)

Now you have a black box (vi), your known signal is easy ('just' numbers, dt and resolution are known)  and you get a result.

In number crunching your precision depends on algorithms and internal resolution ...  lets see what NI can tells us ...

[Bob_Y.]

I don't know if you can still edit this post or if someone at NI can do that ( Molly ?), but you shouldn't put your serial number in the post.

I am sorry that I don't know the answer to your question, but I do know that the precision of the input will affect the precision of the output.  The less precise your input, the less precise your output.  As for the calculation itself I don't know how much you loose.

Sorry,
Bob Young