theswellylife:
Yes. I don't really have the time or space to build a high-order filter. Is there an opamp ic like the LM741 that would do the trick?Thank you. I think I will got with the ISR approach.
EDIT. Thinking about it further, I don't think an ic would help the sharpness in drop off. Hopefully, I am wrong?
You can implement a 2nd order Sallen-Key filter with a single op amp that would roll off twice as quickly as an RC filter. The op amp would also allow you to set the input level to the A/D converter.
Without a very high order filter, you're going to have to sample at a higher rate where the filter has sufficiently attenuated the high frequency content of your source signal.
IIR filters are more computationally efficient than FIR filters, so that would be preferred unless you need linear phase or some other characteristic of the FIR filter. In either case, it will likely be more computationally efficient to implement the digital filter in two or more stages with decimation.