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Apply a transfer function to tailpipe noise?

Experimenter
Experimenter

I have a predicted acoustic transfer function (Pressure over Pressure) from my tailpipe to driver’s ear.  I want to multiply the tailpipe recording of my actual exhaust with the transfer function to hear the sound at driver’s ear.  How can I do that? 

 

And yes you technical purists out there, I know the Pressure over Q is better, but I still want to use the Pressure over Pressure (P/P) function anyway

4 REPLIES

Re: Apply a transfer function to tailpipe noise?

Siemens Phenom Siemens Phenom
Siemens Phenom

Hello,

 

Since you said "multiply the tailpipe recording of my actual exhaust with the transfer function to hear the sound at driver’s ear" I assume you want to do this in the time domain and only have those two pieces of data, transmissibility (Pa/Pa) from tailpipe to driver's ear and operating data at the tailpipe?

 

If that is true, I would us the FILTER_FRF command in the time signal calculator.  That would use the FRF / Transmissibility function to generate a filter that you filter the operating data by.

 

Bring the FRF / Transmissibility function into the Block Set Editor in the Time Signal Calculator.  That will assign it as B1 and then refer to that in the FILTER_FRF command.

 

10-10-2018 1-42-40 PM.jpg

 

 

Re: Apply a transfer function to tailpipe noise?

Experimenter
Experimenter

Cool !! … I didn’t realize there was a FRF Filter option, I think this is exactly what I need.

Thanks for the Help

Re: Apply a transfer function to tailpipe noise?

Siemens Valued Contributor Siemens Valued Contributor
Siemens Valued Contributor

 

I think Kevin's suggestion is a great option ... 

 

Also since you have never used the 'FILTER_FRF' command in time signal calculator to apply a transfer function as a filter to a time history recording I have detailed the the process a little more below:

 

  • Start Desktop module ( Windows 7 : Start -> all programs-> Sim Center Testlab 18-> Desktop Standard & Advance)
  • Open Time Data Editor add-in ( Tools -> Add-Ins -> Time Data Editor - Advance -> )
  • check box on left side of screen then press close

 

 

Q8_P1.png

 

 

  • Go to Navigator worksheet and right click on exhaust recording you want to process then select Replace Input Basket

 

Q8_P2.png

 

  • Go to Time Data Selection worksheet and press the “Add” button (above channel list)
  • Below Data Set check box in “View” column to visualized the data

 

Q8_P3.png

 

  • Open block set editor by selecting (*B) icon in fist row of Time Signal calculator

 

Q8_P4.png

 

  • From Block Set Editor Selection Dialog box Press “Add block…“   

  

Q8_P5.png

 

  • Browse to location of imported FRF data

 

Q8_P6.png

 

  • Note for more information about importing data follow link – Importing Data
  • After selecting your FRF data press “OK” 

 

Q8_P7.png

 

 

  • Note ID for the FRF block set is B1 then press “Close” button 

 

Q8_P8.png

 

 

  • Insert a function into the formula editor by selecting (*fx) icon in fist row of Time Signal calculator

 

Q8_P9.png

 

  • Using first column of Select Function box choose “Conditioning” then in second column select “FILTER_FRF” and press “OK”

 

Q8_P10.png

  • Next fill in the formula arguments (Note sample frequency should be equal to sampling frequency of exhaust recording) then press “OK”

Q8_P11.png 

  • Next step is to press calculate [ lower left corner of page ]

 

Q8_P12.png

  • Now press “Save As …” button and then “OK” to save filtered recording into the project.

 

Q8_P13.png

 

  • Now go to Navigator worksheet and right click on the recording created with time signal calculator and select Audio Replay ( be sure to check that Audio Replay add-in is turned on)

 

 

Q8_P14.png

 

 

Re: Apply a transfer function to tailpipe noise?

Experimenter
Experimenter

Thanks for the instructions! They made the task super easy