anti-aliasing filter

[Tristan111]

Hi community,

I have a cRIO and different NI voltage input modules (NI 9237 and 9205) and I realize an acquisition at a slow frequency (1kHz max) and I want to filter my 32 channels signals above 1 kHz.

My acquisition is very slow so I can’t use digital filters because the analog bandwidth of NI 9205 is 370 kHz for example. If I want to filter digitally I need to realize an acquisition above this frequency.

I think to use anti-aliasing filters but I don’t success to find a rack of 32 filters…

Have you got an idea of an analog filters supplier or another solution for my problem?

Great thanks to anyone's help,

Tristan

[Lysandros]

If you need the filter to be applied "live" then there are different options:

• Create a discrete, first-order low pass filter with the method of finite impuse resonse. Feedback nodes will be necessary here.
• Implement a Point-by-Point filter of labview: search for the VI PtByPt (Butterworth)
• Solder a RLC-circuit inside the NI-9923 terminal block. Only if you have the right skills and tools. By carefully selecting the specifications of the circuit one can implement an analog filter this way, but if not done professionaly it will introduce noise and other EMC issues

If you can also apply the filter after the acquisition ("offline") then you can do this very conveniently with Matlab or Python. There is documentation on that.