Hi,
I had previously written and used an application in Labview to calibrate electret microphones by measuring the transfer function with a reference instrumentation grade microphone. The reference microphone is usually connected to the card in slot 2 and the electret microphone to the card in slot 3. The synchronization of the two cards was simply done by using the Get Terminal Name with Device Prefix of the properties SampleClockTimebase SyncPulse and StartTrigger from slot 2 and feeding them to the appropriate property nodes of slot 3. This worked fine with two 4462, but as soon as I tried using a 4472 in slot 3, I started getting all sorts of errors. In the end I ended having two measured waveforms with a different sampling rate, which as I understand, is due to the onboard oversampling clocks of the two different cards.
I found the following entry on the discussion forum
which is very similar to my problem, but seems to be applicable to the C programming version of Labview.
I tried re writing the code to re-route all signals as indicated in that entry, and now I'm getting a different problem....my second channel is not acquiring data, in spite of the fact of routing both sync and start triggers. I'm sure I'm missing something stupid, but cannot figure out what!
I'm attaching the code to make it easier to understand my problem. The bottom "line" of code is to have a speaker excited with white noise which is necessary for the calibration.
Thank you
Benjamin Fenech
