How to generate real-time tones using Labview? (hardware-programmable codecs or software?)

[bhu1357]

An application that we need is to be able to generate real-time sound/tones in LabView. We are wondering if this would be easier using a hardware or software approach. The hardware approach would involve programmable codecs, while software would involve existing VIs, or a Fourier-based approach (http://sunsite.univie.ac.at/Spreadsite/fourier/fourt32.xls). Any examples would be helpful.

Thanks,

B 

[Hesloppy]

Hi B,

I have a few questions for you.  What version of LabVIEW do you have?  What existing VIs are you planning on using? 

Thanks,

Message Edited by jbryanh on 02-03-2009 02:09 PM

[bhu1357]

Hello,

I have LABVIEW 8.2. I believe I will be mainly experimenting with the continuous sound VI (if that is available for my version?), and trying to get sound to bypass the sound card and go out directly to speakers using some sort of DAQ. Mainly I want to be able to output tones directly to a speaker without going through the sound card, and  to be able to do this in real-time. Thanks,

B

[Hesloppy]

Hi B,

I found a Knowledgebase that mentions the continous sound output vi, but I was unable to find it in the example finder.  I am guessing that is the VI you are talking about. 

Are the tones you want to output saved in files or are they going to be generated? 

What do you mean with real-time?  Do you mean using LabVIEW Real-Time, or do you mean that you would like to read in a sound and output it at the same time?

We have the PCI-4461 card that can do audio input and output.  

Thanks

[bhu1357]

Bryan, 

Thank you for helping out. I have read the article on the continuous sound VI which you gave the link to me for- i need to play with some of the examples in there. The tones we want are to be physically generated, but as stated earlier, directly through speakers, and not the sound card on the computer. Also, I meant LabVIEW Real Time when I meant real-time; i.e. using that environment and having the tone generation be compatible with it.

Thanks,

B

[fay_001]

Hi BI will do the real-time tone analysis, and I want to use B&K 2250 or 2270, and I want to analysis with labview. The sound I will analysis comes from wind turbine on site. Maybe we can discuss something.

[Hesloppy]

Hi B,

This KnowledgeBase talks about getting sound output using a PXI chassis.  This idea should work using LabVIEW real-time.  Do you already have the hardware you would like to use to do this, or are you going to be purchasing some.  

It is recomended to run the output from the DAQ card into an amplifier and then to the speakers.  If you are looking for high performance audio the DAQ card will probably not have enough power behind it to push the speakers.  It will work well as a pre-amplifier though.

Regards,

[bhu1357]

We are currently looking at the NI PXI-6229 DAQ. We are unsure about what kind of gain we will be needing if we use it as a pre-amplifier. Are the VIs modifiable to be able to output sound to the DAQ, and not the computer's sound card? Thanks,

B

[Hesloppy]

Hi B,

You can output sound directly to the speaker if you use a voltage output task.   The output to the speakers is just a voltage.  I have attached a really simple vi that reads a .wav file and plays it from a speaker directly connected to a DAQ card.

Best Regards,