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Acoustic FRF units with Q-Source?

Experimenter
Experimenter

I am using the Q-MED volume velocity acoustic source and MIMO FRF Testing to generate acoustic FRF’s. However, the sensitivity provided for the Q-source has units of mV/m^3 and therefore my measurements have units of Pa/m^3. How can I get the more common unit for acoustic FRF’s of (Pa/m^3/s^2) ?

2 REPLIES

Re: Acoustic FRF units with Q-Source?

Siemens Phenom Siemens Phenom
Siemens Phenom

Hello, this is correct.  The Q-MED is a volume displacement sensor. 

 

Also, if the sensitivity is negative make sure that you reflect that.  Either enter the sensitivity as negative or add the Polarity field to Channel Setup and set that to negative.

 

I guess your next question will be, what to do with the FRF?   The FRF wil be Pa/m^3.  I believe if you integrate that you will get Pa/(m^3/s) and if you double integrate you will get Pa/(m^3/s^2).  I have not used that exciter myself, but that seems to make sense to me if you want Pressure over volume velocity or volume acceleration..  If not, I am sure someone will correct me.

 

Some additional information:

 

10-12-2018 10-21-29 AM.jpg

Re: Acoustic FRF units with Q-Source?

Experimenter
Experimenter

Thanks for the clarification Kevin and the important tip about the sensitivity and polarity !!