Signal processing of AFM (DC) signals using labview

I am trying to conduct FFT analysis on DC signals from the thermal fluctuations of a cantilever (liquid operation) from a Nanoscope III multimode AFM. Our DAQ board is PC6110E. I am using one of the available signal processing examples to process the signal, but we find that there is a lot of noise in our resolved spectra. Similar work using a SRS spectrum analyzer yields very good and clean spectra. Is there any amplification/filtering etc. that can be implemented before or after the DAQ board that can eliminate/reduce this noise? The frequencies of interest of our signal is between 5-100 kHz. Thanks in advance.

Hello;
If the range of frequency would not so extense, you could use one of the NI signal conditioning modules. However, as that is not the case, you will probably need to implement a filter, in Software, to get rid of the harmonics with higher frequency than 100KHz.
Furthermore, I'm attaching a good Application Note that talks about noise on DAQ systems, so you can get some usefull information, and maybe apply some of the techniques on your system to avoid noise.
Hope this helps.
Filipe
Attachments:
Field_Wiring_and_Noise_Considerations.zip ‏196 KB

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