Forrest Sheng Bao's Cyberhome

by Forrest Sheng Bao http://fsbao.net

% Copyleft (C) Forrest Sheng Bao 1984-2009 http://fsbao.net
% with Dept. of Electrical and Computer Engineering and Dept. of Computer Science, Texas Tech University, Lubbock, Texas, USA
%
% This program shows the orders and frequency/phase properties of four different kinds of filters, Butterworth, Chebyshev Type I, Chebyshev Type II and Elliptic.
% The filter is expected to have a cutoff frequency at 200 Hz with attenuation 40 db/octave. The sampling frequency is 2000 Hz.
%
% This program licensed in GNU GENERAL PUBLIC LICENSE (GPL) v3 or later.
% If you do not know what GNU GPL is, please visit http://www.gnu.org/copyleft/gpl.html

A friend asked me an interesting question: Why is Z-transform always related to digital filter design? Well, this is interesting. But the clue is simple.

You need a web browser that supports MathML to read this doc. To see whether your browser supports it, please check whether you can see formulas on this page. By default, Linux and Mac user should be able to make it from their Mozilla Firefox browser. For Windows users, well, that's not a question you should ask me.

The author cannot guarantee this article has no typo. Please confirm all equations before you use them.

by Forrest Sheng Bao http://fsbao.net

You need a web browser that supports MathML to read this doc. To see whether your browser supports it, please check whether you can see formulas on this page. By default, Linux and Mac user should be able to make it from their Mozilla Firefox browser. For Windows users, well, that's not a question you should ask me.

The author cannot guarantee this article has no typo. Please confirm all equations before you use them.

There are so many guys asking me the difference between DTFT and DFT. And, they confused these two concepts with FFT and STFT.

by Forrest Sheng Bao http://fsbao.net

Here are some examples about computing autocorrelation, PSD in Welch methods with different windowing functions.

The problems are from John Semmlow's Biosignal and Medical Image Processing chapter 3. I used the MATLAB routine sig_noise() that comes with the textbook CD.

Problem 3.8 Welch method

Problem 3.9 Direct FFT spectrum vs FFT spectrum of a signal's autocorrelation function

Repeat above problem, but let SNR=0 dB

This blog post is moved to http://forrestbao.blogspot.com/2009/08/hello-world-of-webhttp-python.html

by Forrest Sheng Bao http://fsbao.net

Agilent ADS is a great tool for circuit simulation on Linux.

1. Install ksh

sudo apt-get install ksh

2. Download and extract ADS2009 installation files. Enter the directory that stores all installation files. Run

./SETUP.SH

and follow on-screen instructions.

Be sure to set the proper path for ADS2009. ADS2009 could be very big, 5.5 GB. So it is better to install it on a separate partition other than your root partition, like below.

by Forrest Sheng Bao http://fsbao.net

You can use other VISA connectivity software on Mac OS and Linux. Here I only explain how to make it in Agilents software running on Windows.

Lately, I am facing a problem on capturing the measurement screen from an Agilent E4448A PSA Series Spectrum Analyzer. So I did some Googling and figured it out. Though I only tested on E4448A, I think it works for all supported Agilent Instruments.

by Forrest Sheng Bao http://fsbao.net

I just made a video tonight on how to debug a C++ program in anjuta, the open-source C/C++ IDE for Linux. anjuta is one component of GNOME development suite and thus part of GNOME project. I think it is very good, just a bit worse than Apple Xcode. But it is definitely way better than Microsoft Visual Studio. Microsoft should do some study on user interface design. Proper menu design, window layout and usability is more user-friendly than eye candies. Sadly, Microsoft focuses too much on eye candies, and makes using their software like dating a girl - every step is very complex.

by Forrest Sheng Bao http://fsbao.net

It's really tricky to program in Sicstus Prolog solver.

Bellow is an example

:- use_module(library(clpfd)).
a(X,Y):-domain([X], 1,4), domain([Y], 4, 6), X+2#>Y, labeling([],[X,Y]).

Results on Sicstus:

| ?- [d].
% consulting /home/grad2/fsbao/d.pl...
% consulted /home/grad2/fsbao/d.pl in module user, 10 msec 72 bytes
yes
| ?- a(X,Y).
X = 3,
Y = 4 ? ;
X = 4,
Y = 4 ? ;
X = 4,
Y = 5 ? ;
no

Ref: Constraint Logic Programming over Finite Domains, Sicstus Manual, http://www.sics.se/sicstus/docs/3.7.1/html/sicstus_33.html