Signals and Systems

Topics

Overview of Signals and Systems

Individual Subjects

Some Useful Links to Suppliment or Substitute for a Textbook

Books on Signal Processing

Spectral Audio Signal Processing, by Julius O. Smith III
The Scientist and Engineer's Guide to Digital Signal Processing by Steven W. Smith, Ph.D. The professor likes this one.
Discrete Time Signals & Systems
The Fast Fourier Transform by E. O. Brigham This was one of the professor's textbooks when he took this class.
Mathematics of Signal Processing: A First Course, by Charles L. Byrne Good chapters on Computer Aided Tomography (CAT Scan) as well as a lot of other interesting things.
Signals & Systems, with MATLAB/Simulink, Karris

Fourier Series

Fast Convolution Based on the FFT This reference shows how end effects are dealt with. To use the FFT for convolution, you need to do it in blocks, which leads to end effects, and more latency, but if your blocks are big enough, it speeds up the convolution.

The truncated Fourier series or DFT method of FIR filter design gives the best approximation of the desired frequency response in a least squared error sense, but it is not very good near discontinuities. The Parks-McClellan (Remez) iterative algorithm gives equal ripple in the pass band and stop band. This is the best in terms of minimizing the maximum error in each area, which is usually better in the real world. MATLAB/octave have automated functions to do that. See remez() in the Signals package of octave.
A nice detailed description of the Parks McClellan algorithm with MATLAB/octave code.

Adaptive FIR Filters

Introduction to Adaptive Filters, Simon Haykin

Simon Haykin's book chapter

Adaptive LMS in an FPGA

Scott Douglas' chapter on Adaptive Filters has some interesting applications, among them linear predictive coding (LPC) used in speech codecs.

Adaptive Filters In the Frequency Domain

Adaptive Filter Echo Cancellation

Adaptive Filters and Applications (Mathworks)

More Applications of Adaptive Filters

Constant Modulus Algorythm

Using the CMA on antenna arrays

Math Editors

LaTex: I suggest opening opening the following sample file with any of the LaTex editors below. LaTex is a document processing language that you compile like C or other compiled languages. It does produce the nicest looking documents, but it takes a bit of expertise to do that. If you are bound for graduate school, it is well worth learning.
- TexStudio works with Windows, Linux, and OS X, has a previewer, menus to help newbies, and is about the most featured LaTex editor I have tried.
- Texmaker is a LaTex editor with preview and a bunch of menus that help to figure out what you need to type to get the effects you want. It works on Linux, Windows, and OS X.
- Gummi is a LaTex editor with preview for Linux and Windows.
- Online LaTeX Editor especially for equations. This is useful for other systems that take LaTex input when you don't know LaTex yet.
Lurch is a math editor for your desktop that will check your logic. For this class it is primarily useful as an easy editor for mathematical subjects.
wxMaxima is a document based GUI for the Maxima computer algebra system. You can do quite a bit of algebra and calculus in wxMaxima. The notebooks it produces look good, but not as good as LaTex documents, however, you can easily change them, and it will redo all the math with the changes. I found a bug in the version that come with Ubuntu 15.04 where it segfaults when you type in a parenthesis to one of the helpful windows that come up when using the menus. I solved it by using the nightly builds from Peter Pall. As with most of the tools here, it will integrate in with LaTex.
SageMath is a computer algebra system similar to wxMaxima that uses python, maxima and other tools to make a very nice and powerful tool for making a notebook.
- SageMath on the cloud uses sage (a computer algebra system) and latex to make your document. It has a nice preview that shows you what you get with your LaTex code. It also has a Linux terminal that you can use for octave and other things. You can create all kinds of files. It works well with the online LaTex editor below.
PTC Mathcad works for Windows and costs something.
LibreOffice is an open source word processor.
Microsoft Word is a fancy word processor that I think you can get for free or minimal cost when you are a WWU student.

Course Pages

2005-2006 Assignments

2006-2007 Assignments

2008-2009 Assignments

2009-2010 Assignments

Class notes for Signals & Systems

Articles

Octave Tutorials

A nice list of MATLAB tutorials from Duke University

Installing Octave on a Mac (Chris Lau)

Octave and Scilab on a Mac (Ben Henry)

Installing Octave (with the GUI) from source on Ubuntu

ASN2 - Octave Tutorial (Jodi S. Hodge)

A u(t) function example

FIR Filter Example Code for Octave

FIR Filter Design and Testing Using the DFT

Leakage Example Octave Script

Interpolation using the DFT Example Script

An example showing how convolution is just a dot product

Tuner Upper Removal Demonstration

Airplane Noise Removal Demonstration

Final Project (2011)

Matlab/Octave deMorse.m

morse.m This is the one from mathworks

Table of Fourier Transform Properties

Homework Assignments

Please put your name next to the assignment, linking it to your submission

HW #1 - Make a personal page on this wiki (Chris Lau)(Jodi S. Hodge)(Chris Wills)(Victor Shepherd)
HW #2 - Write a tutorial about installing and/or using Octave (Chris Lau)(Jodi S. Hodge)(Victor Shepherd)
HW #3 - Show graphically that $\int _{-\infty }^{\infty }e^{j2\pi f(t-u)}\,df=\delta (t-u)$ (Chris Lau)(Jodi S. Hodge)(Chris Wills)(Victor Shepherd)

HW #4 - Given a linear time-invariant system where $\ u(t)$ produces an output $\ w(t)$ , find the output due to any function $\ x(t)$ (Chris Lau)
HW #5: (Chris Lau)
- Part 1 - Find ${\mathcal {F}}[e^{-\sigma t}x(t)u(t)]$ and relate it to the Laplace Transform. Derive the Inverse Laplace Transform of this from the inverse Fourier Transform.
- Part 2 -

HW #6 - Pick a property of the Fourier Transform & present it on the Wiki. Make a table with all your properties. Interpret your property. (Ben Henry)(Chris Lau)(Victor Shepherd)
HW #7 - Finish the practice tests
HW #8 - Make a page about interpolating FIR filters. Note how many multiply/add operations.(Jodi S. Hodge)(Chris Lau)(Victor Shepherd)
HW #9 - Add to #8 writeup how to do a decimating filter and figure out how many multiply & adds are needed for a n/2 decimating low pass filter.(Jodi S. Hodge)(Chris Lau)(Victor Shepherd)
HW #10 - Use Octave (or Mathlab or Silab) to plot the frequency response of low pass filters with cut off frequencies of 1/32T, 1/8T, and 1/4T and compare how many coeffficients are needed with an eye to answer the question "Is it less calculation to decimate and then filter, or better to put the filter in the pre-decimation filter?" (Jodi S. Hodge)(Victor Shepherd)
HW #11 - Is our method the same as Mark Fowler's? See

Wiki. Same # multiply and adds? See Notes 11/3/10. (Jodi S. Hodge)(Victor Shepherd)

HW #12 - Experiment with a variety of signals having a 3Khz bandwidth to determine the resolution you can get when doing a cross correlation $\ r(m)=\displaystyle \sum \limits _{n=0}^{N-1}x(n)x(n+m)$ . You can generate the signals randomly and filter them to obtain the band-limited signals. (Jodi S. Hodge)
HW #13 - Derive the following realtions:
- a) $DFT(x(k-l))\!$
- b) $DFT(e^{j2\pi lk/N}x(k)\!$
- c) $\sum \limits _{k=0}^{N-1}x(k)y(k)^{*}=c\sum \limits _{k=0}^{N-1}X(n)Y(n)^{*}$ (Victor Shepherd)

HW #14 - Come up with a use for an adaptiveFIR filter and make an Octave script to demonstrate it. (Jodi S. Hodge)(Victor Shepherd)
HW #15 - Do Practice Exam II (Victor Shepherd)
CW-Robot Octave Simulation