I'm not very strong in analog stuff, and particularly not in RF, so I could use some advice. :D
I'd like to tie the output of an LM35 to the ADC pin of an XBee module. The desired range over which I'd like to log is 10C-35C. Anything below or above that can simply be logged as out of range.
Since the signal would be between .1 and .35V, in order for the ADC to read it with accuracy and precision, I'd need a pretty low reference voltage - but even then, noise of just a few mV can be a problem.
So, I would think that an op-amp with some gain and a higher reference voltage would be a good thing. That brings me to my first question: Is that thinking on the right track?
Since this will be in the same (small) enclosure as the radio, I would think that using a low-pass filter would be in order, perhaps even an RC between the LM35 and op-amp, and another between the op-amp and ADC pin. Since it will be in close proximity to the radio, a small inductor would also seem in order. So, my second question: Am I going about the filtering correctly, or is there a much better way to keep things clean?