Acquisition on the trigger channel using PXI-4472?

[jfblais]

Hi,

I have a PXI-4472 board and I would like to acquire my 8 channels simultaneously using an analog trigger. Since I also want to use the trigger signal as a reference signal to calculate a Frequency Response Function (FRF), I was wondering if there is a way to acquire the whole trigger signal even if it is connected to a Trig. or External Trig. input.

I'm using a PXI-1042 chassis which includes the PXI-4472 board (8 channels + external trigger) and general ports like USB, GPIB, etc. (and also a trigger input).

All inputs are microphones to perform array measurements and since I'll will displace the 8 microphones array, I absolutely need a reference signal.

Otherwise, I would have to use only a 7 microphones array with my reference microphone connected to the other free channel....

Thank you,
J-F

[Nathan_R]

Hi jfblais,

With the PXI-4472 the External Trig. input is a digital TTL input. So it can only be used for digital edge triggering. For analog edge triggering you must use one of the 8 analog input channels. So in your case you could have 7 microphones and use the eighth channel to acquire your reference signal and to trigger from. If you have additional cards that support analog trigger you could acquire and trigger off your reference signal using those cards and then export the trigger to the PXI-4472. When using two cards it will be easiest to keep the reference and microphones synced if both cards are DSA devices, but it can be done using other types of analog input as well. Let me know if this helps.

Thanks,

[jfblais]

Thank you for your answer As I expected, I will use 7 microphones instead of 8... Since the other trigger I have is the one included on the PXI-8186 embedded computer kit and is a software-controlled trigger I won't be able to use it either. Am I right? Thanks again, J-F

[Nathan_R]

Hi jfblais,

Yes, the software controlled trigger on your PXI controller uses digital edge triggering like the external trigger on your DSA card. It does not support analog triggering or acquisition. SO you best option is going to be using 7 mics and the 8th channel for triggering. I’m glad I could be of help. Let me know if you have any more questions.

Thanks,