EEL 4514 - Communication Systems and Components - Spring 2005

Dr. John M. Shea

• Announcements
  • Final exam information
    • The final exam (for those who take it) will be on Wednesday, April 27th, 3:00 PM - 5:00 PM in NEB 202.
    • Study guide for final exam
    • Sample questions (from last year, so some parts may not be relevant)
    • Solutions to sample questions
  • Exam 2 information
    • Last year's exam
    • Study guide
  • Exam 1 is on Thursday, March 17th during 4th and 5th periods in the usual room, NEB 202.
    • Study guide
    • Last year's exam
    • Solution to part 2 of last year's exam. Sorry, I don't have a solution to part 1 on hand, but it should be straight-forward with your notes available. Feel free to e-mail me with questions.
    • Here are some more notes on the relation between Fourier Series and Fourier Transform from Dr. Couch's book
  • The TA's office hours will be 5th period Tuesday, 6th period Thursday, and by e-mail.
  • I mentioned that you can build a simple parabolic reflector to improve the performance of your wireless LAN (in one direction!). The template I used is for the Windsurfer from freeantennas.com, but they also have some other templates.
  • Please read the course syllabus carefully.
• Lecture Materials
  • Brief history of wireless communications (focused on cellular comm.)
  • Table of historical dates relating to communications, from Dr. Couch's book (see syllabus for full citation).
  • Information on frequency bands and propagation modes from Dr. Couch's book
  • fourier_series.m The MATLAB function for generating the Fourier Series coefficients step-by-step. Note that it is better to save it as a file (usually via right-clicking on the link or shift-clicking on the link) than to try and copy and paste it to a file. Generally you will want to save it as "fourier_series.m" and make sure that you either use the cd command in MATLAB to change to the same directory where you saved that file or else add the directory where you saved the file to your MATLAB path.
  • Properties of Fourier Series
  • Relation between Fourier Series and Fourier Transform from Dr. Couch's book
  • Spectra of FM or PM with sinusoidal message signal
• Quiz Solutions
  • Quiz 1 Solution
  • Quiz 2 Solution
• Assignments:
  • Homework 1, due Feb. 1
    • Problem statement
    • Solution
  • Homework 2, due Feb. 17
    • Problem statement
    • Solution, part 1
    • MATLAB code for problems 5 and 6
    • Figure for problem 5. I had meant to specify a carrier frequency of 1.9 GHz, but I typed 11.9GHz. This if the 11.9 GHz result. Note the severe variations in received power with distance. At very short distances, there are not enough points in the graph to accurately reflect the performance. As the distance gets very large, there is a last lobe that rolls off at 20 dB/decade (same as free space). This is a little easier to see if we either plot the result for a larger distance range or consider the frequency I intended by looking at the results for 1.9 GHz carrier freq.. The received power drops from -9 dBm at 1e4 m to -28 dBm at 1e5 m, which is 19 dB/decade.
    • Figure for problem 6. Note how much faster the power rolls off if the ground reflection coefficient is -1. In particualr, for large distances, the slope of the curve is 40 dB/decode (same as exponential path loss with n=4. As before, this is easier to see if you plot the result out to a larger distance or consider the performance results for 1.9 GHz. The received power drops from -4 dBm at 1e4 m to -35 dBm at 1e5 m, a loss of 39 dB/decade.
  • Homework 3, due Feb. 24
    • Problem statement
    • Solution
  • Homework 4, due March 11th by 4:45 PM in EB 440.
    • Problem statement
    • Solution
  • Homework 5, due at beginning of class on March 29th
    • Problem statement
    • Solution
  • Homework 6, due April 8 by 4:45 PM in EB 440
    • Problem statement
    • Solution
  • Homework 7, due April 11 by 4:45 PM in EB 440
    • Problem statement
    • Bessel function table
    • Solution
• Reference Material
  • Convolution is easy to play with by using the Joy of Convolution Java applet.
  • There are a variety of other signals and systems demonstrations at this Johns Hopkins website.
  • MATLAB Tutorials and Information
    • MATLAB Hypertext Reference
    • Getting Started with MATLAB from the Athena computer system at MIT
    • Another MATLAB page from MIT
    • Learning MATLAB from T. Green at Contra Costa College