Battousai,
By analog filter, I assume you mean the front-end AC coupling filter. This filter basically blocks the DC portion of the signal, since it is a high pass filter with a cutoff frequency of 3.4 Hz (or 0.5 Hz in the 4472B). This filter is enabled by turning on AC coupling in software, and can be disabled by selecting DC coupling.
The digital filter, which is an anti-aliasing filter, is part of the analog to digital converter (ADC) and cannot be turned off. It filters out all of the unwanted images of the sampled signal, which yields a sampled signal with less distortion. I hope gives you get a better understanding of the filtering done on the 4472, have a good day!
Sincerely,
RossC
