You need to transform analog input from the real world to something digestible to the digital world.

Some definition:

• Signal to noise ratio: $$\hbox{SNR} = {P_\hbox{signal}\over P_\hbox{noise}}$$
• Effective number of bits: indicated as ENOB

this holds (calculation)

Nyquist-Shannon sampling theorem

Signals that differs of $${1\over T}$$ are sampled the same

Oversampling and decimation

In same cases you can improve the resolution of your ADC of $$n$$ bits simply summing together $$f_\hbox{oversampling} = 4^n \cdot f_{\hbox{sampling}}$$ and then scaling by a factor of $$s = 2^n$$. This is possible if the following assumptions hold

• the signal of interest should not vary significantly during a conversion
• there should some noise in the signal with amplitude at least 1 LSB