Record sound in sync with other DAQ tasks

[josborne]

Hi !

I built a measurement system that performs the folowing tasks simulatenously:

• Analog input:   Records 8 analog inputs to disk at 5kHz apiece.
• Digital output:  Outputs a digital pulse train which triggers the shutter on a firewire camera.  These images are then recorded to disk using IMAQdx.
• Digital input:  Monitors a collection of digital lines for error conditions and shuts down accordingly.

The above tasks are all syncronized using digital triggers and a shared sample clock.  In this manner, the grabbed video images and the AI are accurately synced!

I am using a Win7 64 bit computer (Core i7) and a NI USB-666 w/simultaneous inputs

MY BIG QUESTION:

How can we ALSO record sound to disk (eg a WAV file) and keep it accurately synced with my analog and video data?  I don't think I can use a sound card, unless I find one where I can input my own sample clock.  Or could I just connect a microphone to my USB-6366 and record the microphone voltage?

I am a newbie when it comes to sound recording.  Any help is appreciated.

[mikeporter]

If you want it sync'd with the other data, it will need to come in through the DAQ card. Remember "sound" is just a human biological interpretation of a physical phenomenon.

Mike...

[josborne]

Yeah, that was what I was thinking. 

So is it possible to wire a mic to one of my analog inputs and record the sound.  And then convert that voltage to a wav file?

Having trouble finding and examples for this on ni.com.

[mikeporter]

You could, but it would probibly get better results if you measured the output of an audio amplifer that is being driven by the microhone. The problem is that microphones tend to be pretty low-level devices so reading them directly could cause noise problems.

In terms of an amp, unless you are particularly concerned about amplitudes, any cheap thing you could pick up at radio shack would work.

Mike...

[johnsold]

You will probably need an amplifier. Most microphones put out very low level signals.  You will also need to sample faster. 5 kHz sampling means that the audio bandwidth would have to be less that 2.5 kHz to meet the Nyquist criterion and that will give very poor audio quality.

Lynn