ECEN 2250 - Introduction to Circuits & Electronics

Peter Mathys, Fall 2011

Circuits in Context

These are assignments that require that you investigate a given topic in sufficient depth that you can write a self-contained essay or report that details your findings in a logical, relevant, and well-supported manner. Your work will be graded for both the writing performance and the technical/content performance. Here are links to the Technical Essay Evaluation Rubric and the Technical Report Evaluation Rubric that will be used for grading.

Assignment 1: "Characterization of Waveforms in Matlab"
For this assignment the following waveforms x(t) are given in .wav files with a sampling rate of 44100 samples/sec.

• Test.wav: Sinusoidal test signal.
• Sinusoid.wav: Another sinusoidal signal.
• Physical.wav: Speech signal (conversation).
• Kia.wav: Speech signal (advertisement).
• Mozart.wav: Music signal (classical).
• Moon.wav: Music signal (alternative).

Feel free to add any other waveform that interests you to this list. The goal is to analyze these signals using Matlab and determine the following quantities:

1. The minimum amplitude value X_min.
2. The maximum amplitude value X_max.
3. The peak-to-peak value X_pp.
4. The peak value X_p.
5. The average value X_avg.
6. The root-mean-square value X_rms.
7. The peak-to-rms ratio X_p / X_rms.

An example of how to display the computed values for the signal Test.wav is shown in the following graph:

Some general explanations about the representation of waveforms in digital computers with emphasis on Matlab, together with more Matlab examples, can be found in Waveforms in Matlab.

Your task is to write a Technical Report (check the Technical Report Evaluation Rubric to see the grading criteria) that addresses the following topics:

1. Description of how you used Matlab to extract the required quantities from the wav-files. This includes a verbal description, any Matlab code that you used, any difficulties that you encountered, and the method(s) that you used to verify that the results that your progam(s) produce are actually correct.
2. A presentation of the results for the different wav-files and a characterization of the most important features of each sound sample.
3. An interpretation in terms of what you learnt about different types of sound signals and how you think that that affects the design of amplifiers, transmission cables, and radio transmissions for which the FCC (Federal Communications Commission) imposes strict limits on signal purity and the maximum transmitted power. Of particular interest is the minimization of the peak-to-rms ratio X_p / X_rms (why?). Is it possible to design a signal waveform for which this ratio is 1.0? If so, what is this waveform?
4. A reflection on how this assignment is related to the Student Outcomes 3a...3k which ABET is using as a major criterion for judging whether students attain the educational objectives of the programs in which they are enrolled. ABET, Inc, is the recognized accreditor for college and university programs in applied science, computing, engineering, and technology. The EE and ECE Bachelor of Science programs of our department are ABET accredited. For your reflection, pick three criteria that you think are most closely related to this assignment.

Your Technical Report has to be typed (formulas and drawings written by hand are o.k.) and any materials from outside sources have to be referenced. Graphs need to be scaled properly and they need to be labeled. Your arguments need to be logical and substantiated. As a minimum, the report needs to have a paragraph for each of the topics listed above. Overall, the report should not exceed 5 pages in length. The due date for this assignment is Mon. 9/12/11.

©2001-2011, P. Mathys. Last revised: 9-08-11, PM.