Write a two page paper, double-spaced and in your own words, describing why (or how) an FFT (Fast Fourier Transform) was used to "decode" the DTMF frequency code (pattern) used in telephones in the lab activity (performed by the class when you were absent, you can read about this in the lab manual). Please describe the main feature(s) of an FFT and what the DTMF is as a part of this. Be sure to include the following key words in your paper: frequency, frequency spectrum, harmonics, beats (of sound waves), beat frequency. Please be sure to cite your references, such as books you use, web addresses for the pages you used.