Devon Finninger
EE2170-L01 Fall 2010
9/28/2010
EE2170
Design and Analysis of Signals and Systems
Lab 5: Fourier Transform
A. Objective
In this lab we will explore the Fourier transform of a synthetic periodic signal and a
non-periodic EKG signal. The goal of this lab is to learn how to implement the
Fourier transform in MATLAB.
B. Procedure
I implemented the Fourier transform in the function FT using a MATLAB realization
of the formula for a Fourier transform.
For part (b) I coded the synthetic periodic signal into an m-file and after taking the
Fourier transform I found the frequency components to be +/- 50.0065 Hz.
In part (c) I constructed another MATLAB file that took the EKG data instead of the
synthetic equation and found the Fourier transform. The fundamental frequency is at
7.1 rads/sec. Also I found the average heartbeats per minute to be 68.1431bpm. The
small spike in frequency on the graph is at 60.0173 Hz. The frequency of standard
AC is 60 Hz, so it is safe to assume that the spike is due to background EMF
fluctuations caused by the AC in the testing room.
C. Conclusion
In this lab we moved from Fourier series into Fourier transforms. After viewing the
transform of the EKG signal I was not expecting the spike at 60Hz caused by the
background AC in the room; however, it makes sense that this would happen
considering the prevalence of AC in nearly any modern structure. I feel that I have
gained a better understanding of the Fourier transform and some of its practical uses.