Dynamic Signal Acquisition

[Hellothworld]

Hi,Guys:

    Recently I encouter a problem about Multimedia product audio  line in test.

    The multimedia product play out a step sweep signal from 100HZ to 10KHZ(10 steps,every step duration time is 200ms), my question is how to analyze this kind of signal using SVT? I want to caculate the every step frequency amplitude,frequency accuracy and THD.

    Thanks very much.

    Leo 

[dsb@NI]

Acquire the signal. Process each 200 ms frequency step as a separate block of data.

For the analysis, you can use the single-tone measurements VIs found in

Functions>>Sound and Vibration>>Single Tone Measurements

Functions>>Sound and Vibration>>Distortion

For frequency accuracy, are you looking to quantify the difference between the detected tone frequency and the expected tone frequency? Or are you trying to make a measurement of small frequency variations within each 200 ms window?

[Hellothworld]

Hi,Doug:

Thanks for your reply.

For frequency accuracy, just compare the acquired frequency with the expected tone frequency.

Based on your reply,I also have 2 questions:

1,How to seperate the audio signal to single block?

    One way I think as follow: Use the AI analog Trigger to capture the whole audio sweep signal,then seperate this signal from trigger point   into several

160ms block(To ensure the analysis accuracy, select 80% part of the 200ms block) , and then analyze it?  

    How do you think of this method?

2,If the output sweep signal is Chirp type, how to analyze the frequency response and  THD during the whole  sweep frequency?

 Thanks.