# What is the purpose of the series of actions: amplification, band-pass, rectification, and low-pass?

Can someone describe for me in simple words (if possible) what happens to a signal if we:

1. Amplify it by $\times 40,000$

2. Band pass filter it (750-5000 Hz)

3. Full wave rectify it

4. Low pass filter it (<200 Hz)

This series of actions is taken from this paper (page 7 - recording of neuralactivity)

Thank you!