Decoding AFSK

[maxpower]

I've got a project that requires the decoding of an AFSK signal.  What I'd like to do is write this using LabVIEW, but I'm not sure how to go about this.  The signal is an 8-bit synchronous data stream with a baud rate of 520.83, logic zero is 1562.5 Hz, and logic high is 2083.3 Hz.  I have a sample audio file and I'm routing the output from the sound card to the analog input of a PCI-6014 DAQ board.  I'm using the DAQmx 8 tools to read from this input on the DAQ board.  Within the block diagram, I am using the "Extract Multiple Tone Information.vi" but get an error -20315 (The waveform dt parameter is <= 0.).  I'm thinking that if I can get the tones, then I can run these through a software filter and later through a compare to determine the logic level needed to intreperet the signal, but I can't get beyond the "Extract Multiple Tone Information.vi" error.  Any ideas or examples?

using:
Windows XP
LabVIEW 8.0
DAQmx 8
PCI-6014

Thanks,
tsc

[Jarrod_S.]

What type of DAQmx acquisition are you doing? What type of sample clock are you using for the acquisition? If you are using implicit timing from an external source, or you are reading data On Demand, then the DAQmx driver won't be able to determine what the sampling rate will be. In that case it will output a zero for dt, which makes it impossible to use these waveform analysis libraries. You can find more information about this here. You should probably probe your waveform to see if your dt is indeed zero. If it is and you know what the dt value should be, you can reconstitute that value in your waveform using the Build Waveform function in the Waveform palette. It works a lot like the Cluster Bundle by Name function if you're familiar with that one. Hope this helps!