# Sampling&ADC

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`