Enable antialiasing filter or not?

[Danfu]

Dear all,

We have a PXI-6115 DAQ board. We use it for reading data from photodiode (after lock-in amplifier) at an input rate of 25kHz.  I realized there is an antialiasing option coming with the DAQ card itself. It can low pass filtering signal at either 50kHz or 500kHz. I was wondering how much help it will do to reduce noise at higher frequency. If it helps, how to enable it in Labview-CVI programming? Thank you very much in advance.

Best Regards,
Dan

[ryannorthington]

Danfu,

The anti-aliasing filter on our DAQ cards is applied before the signal reaches the ADC.  So any frequency content that is higher than the two presets on the 6115 (50kHz or 500kHz) will be attenuated.

You can access this property in CVI by using the AI_Change_Parameter function to set the filter value.  You can find this information in the 6115/6120 User Manual on page 101.