I am looking for a LabView programmer to volunteer time for an endangered species project.

[JayB33]

I need to produce an analog signal that mimics the click of an endangered porpoise.  We are developing a method of acoustically monitoring vaquita in the Gulf of California using their echo-location clicks.  We need to produce simulated clicks to test this equipment.  We have both M-series (USB-6251) and E-series (DAQCard-6062E) A/D/A equipment as well as the amps and transducers to output the signals.  We have a synthesized porpoise click available in a WAV file (133 kHz, 100 uSec).  We are lacking the software to output the analog signals.  Is there anyone out there who could write stand-alone software to read a WAV file and output it to one of our NI devices (we don't own LabView or have any expertise with it)? 

[Ray.R]

You may also want to post in the job section:  http://forums.ni.com/ni/board?board.id=JobPost

[Wiebe@CARYA]

We can make you an application for the USB-6251.

My colleage will post it soon. To prepare, install the LabVIEW 8.5 Run Time
Engine and the newest DAQmx drivers (both are downloadable from the NI
website).

Regards,

Wiebe.

[Wiebe@CARYA]

Btw. Why don't you use a sound card as output?

[andre.buurman@carya]

This application should be able to output 2 channels of the wav file to AO0 and AO1 of at least the USB-6251 device.

It requires that you install:

1. The DAQmx drivers;
2. The LabVIEW 8.5 (or 8.5.1) runtime engine.

I have included everything (source) necessary for people to add to the code.

Executable can be found in Builds/EXE.

[JayB33]

Thank you, Weibe and Andre!  I'll try it on Wednesday (I'm going out to sea for 2 days to check on some equipment).  This should be just what I am looking for.  I cannot use a sound card because the signal is 133 kHz, and to accurately approximate the waveform, I want to output it at 1 Ms/sec or higher.  Jay.

[Knipster]

Have you considered using a DAW? (Digtal Audio Workstation). This would make converting the WAV file you have to  an analog output at a  Line level very easy through any consumer computer. (Possibly the computer the hold your DAC/ADC. If the Transducers that you are using can handle the output of your audio card, then using a program like Ableton Live, for instance would make creating a solution to your situation very simple.

I'd be very interested in trying to help.

;^D

[andre.buurman@carya]

Why output a waveform of 133 kHz with 1Ms/s? This will transform the original signal in a 1MHz signal. Thus an original sample of size 133000 will take 0.133 seconds instead of the original 1 second.

At the moment the code reads the sample frequency from the wav file and uses that as the sample frequency for the output channels.

[JayB33]

Kipster,

The problem with using DAW with audio cards is that they max out at about 192 Ksamples/sec.  I need an output that is 5 times higher in frequency.  Commercial audio gear is not intended for sounds that humans cannot hear.  Porpoises make sounds that are 10 times higher in frequency than most people can hear.

Jay

[JayB33]

Andre and Weibe,

I am having trouble with the software you posted.  It is not outputting signals to the AO0 or AO1 ports of the USB-6251.  This is true with my WAV files and with the "tada.wav" file that was included with the software.  The waveforms display in the window and the green check mark indicates that there were no error messages.  I've tested my USB-6251 with the NI Test Panel and it outputs signals OK.  Perhaps you'd be willing to help me debug my problems?  We can do this offline if you want to email me (jay dot barlow at noaa dot gov) (no spaces).

Andre,

1 MHz is the digitization rate of my wave files.  133 kHz is the fundamental frequency of the vaquita echolocation click.  The digitization rate needs to be at least 2 times the fundamental frequency, but this nyquist rule would apply to Digital/Analog conversion only if the DA hardware had a perfect interpolator.  With a typical non-interpolating DA output, the sample rate must be several times the fundamental frequency in order to accurately approximate a sine wave.

Jay