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Friday, February 19, 2016

On a Serious Note

In spite of the daily ups and downs of our busy human experience, we should focus on seeking wisdom as well as knowledge, and the truth. Sometimes, it helps to take a step back and just let go and let God, and ease our minds. A prayer from Matthew 6:9-13, the Lord's Prayer, is helpful:


Our Father in heaven,
hallowed be your name.
Your kingdom come,
your will be done,
on earth, as it is in heaven.
Give us this day our daily bread,
and forgive us our debts,
as we also have forgiven our debtors.
And lead us not into temptation,
but deliver us from evil.


Favorite DSP and FFT (Fast Fourier Transform) Links

Here are some of my favorite links I've collected over the years of teaching FPGA design and DSP implementation. Please contact me if any go down. Enjoy!

Embedded Systems

Compression FAQs (see especially part 2) http://www.faqs.org/faqs/compression-faq/
Short technical introduction to JPEG (a gzipped PS file) http://www.ijg.org/files/wallace.ps.gz

Huffman Coding with an example using characters: LINK
Practical Huffman coding (includes decoding): LINK
High level encoding/decoding algorithm sketches: LINK

Filters

http://www.dspguru.com/info/faqs/firfaq.htm FIR Filter FAQ and ScopeFIR software

Link to a project to create a FIR filter PDF
Linear Feedback Shift Register (LFSR) useful in FIR filter http://homepage.mac.com/afj/lfsr.html

Interesting use of hardware FIR filter: http://www.tele.ntnu.no/akustikk/meetings/DAFx99/baron.pdf

DSP Processors

TI DSP Simulator Paper (describes VLIW technique)
TMS320C6000 Programmer's Guide (Rev. G) (TI DSP Programmer's guide)
TMS320C64x Technical Overview (Rev. B) (TI C64x DSP reference--a specific type of C6000 series)


FFT/DSP

comp.dsp is perhaps the newsgroup best suited to discussing the FFT/DSP

FFT TUTORIALS

Bores DSP tutorial (excellent DSP tutorial!)
http://home.ewha.ac.kr/~slee/slides/dsp/hw4_supplement.ppt (WOW a detailed look at the BUTTERFLY COMPUTATION even splitting up the real/imaginary components!)
http://www.math.tau.ac.il/~baizen/A_D1.PDF    Appendix D-1. Fast Fourier Transform (FFT) (good explanation of the equivalence of the equations using 'e' and those using 'sin' and 'cos')
INSANELY HUGE BUNCH OF LINKS TO DSP!!! To bad it's only in cache form under Google as it went away recently. You could literally go crazy looking through all of them: Jinno's DSP Links
Re: Fast Fourier Transform tutorial www.lns.cornell.edu/spr/2002-02/msg0039339.html
Digital Fourier Transform (summary and mathematics from ReliSoft)
Fourier Analysis (wonderful explanation from ReliSoft)
FFT (tutorial on FFT from ReliSoft)
SkylondaWorks Radar Signal Processing Scrapbook (chock full of information about bit reversal, sine table, butterfly computation, etc.)
Fast Fourier Transform (FFT) (no need to install language pack; mathematics of the DFT and FFT)
http://mayaweb.upr.clu.edu/crc/crc2003/papers/Alberto_Quinchan.pdf (mainly because 2nd page shows butterfly operation)
Fast Fourier Transforms (more than you wanted to see of FFT algorithms—useful in seeing different implementations of algorithm)
VFX Appendix A - The FFT (another plain language description—not useful for implementation but useful for overall understanding)
http://www.dspdimension.com/html/dftapied.html (painstakingly detailed explanation of DFT)
http://klabs.org/richcontent/MAPLDCon03/abstracts/helgemo_a.pdf Digital Signal Processing at 1GHz in a Field-Programmable Object ...
http://www.eptools.com/tn/T0001/PT04.HTM The Radix 2 Decimation In Time (DIT) Algorithm.
http://www-star.stanford.edu/~bbaas/fftinfo.html FFT Processor Information Page
http://products.zarlink.com/product_profiles/PDSP16116AMC.htm PDSP16116AMC - 16 by 16 Bit Complex Multiplier (Zarlink ...

FFT PROCESSORS and other hardware

http://www.idt.com/docs/7052_AN_3471.pdf (four port SDRAM to support DSP)
http://www.icommtech.com/Products/FFT-64.PDF 1024 point FFT chip (Nov. 1999--kind of old as chips go)
http://www.iberchip.org/VII/cdnav/pdf/50.pdf (A bit serial FFT processor)

Floating Point

http://www.validlab.com/goldberg/paper.pdf (paper on floating point mentioned in class)
http://www.cs.tau.ac.il/~danha/courses/SEM2002/ami-floating-web.ppt     (contains example of using round and sticky bits in floating point)

The Art of Computer Programming

Today's post is a review of Donald E. Knuth's The Art of Computer Programming. This venerable classic is all but forgotten perhaps in the fast-paced world of fly-by-night computing. I for one, purchased a copy of the 3-volume set about ten years ago while a professor, and I find it convenient as a reference, or simply for some good reading.

This page on mathematical induction is but one of many useful pointers for computer science students and practitioners alike.
In the case of computer science practitioners, referring to a page such as the one on mathematical induction, isn't something we do for fun, it's something we MUST do, for the benefit of our clients, and our ongoing growth. You are growing and learning constantly as a computer practitioner, or you're falling behind. There is no standing still.

The organization of the book is in three volumes: 
  1. Fundamental Algorithms
  2. Semi numerical Algorithms
  3. Sorting and Searching
Want to know about garbage collection, before it was "cool"? The Art has it. Section 2.3.5. Thank you. Follow the symbols to understand: they are made to be language-independent so that any programmer can understand them without the baggage of a specific implementation. Perhaps, you'd like to make sense of the statistics you gather on a daily basis from your A/B testing? Check out Statistical Tests in Volume 2. I learned a lot about the statistical analysis package SAS as a doctoral student, then proceeded to publish tests to help prove that method B was better than method A with a certain confidence. SAS is great if you have access to it, but most of the time we perform simple enough tests that we could write a program to analyze the logs ourselves, and have the benefit of customizing the result presentation, given a little know-how gleaned from a good numerical analysis book. That's where Knuth's book comes in. Finally, if you want to know all about commonly-used searching and sorting techniques, and some not-so-commonly-used ones (but very useful), check out volume 3. Now, there are some sections dealing with tape merging, but keeping an open mind here, yesterday's big data was a lot smaller than today's, but the methods can be transferred.
The three-volume collection of computer science know-how!


In short, don't pass up the opportunity to purchase this classic and actually use it. Reading it cover-to-cover is useful for those who like to do so, but it is so easy to locate specific topics, it makes a great topical reference for the modern computer scientist.

How I Was Introduced to iPhone App Development

Many people wonder what is the procedure for starting to make iPhone Apps. There are a ton of websites, but I suggest you visit Apple's. I did a lot of searching, and it turns out that you really are better off purchasing a Mac with the latest OS X version, then installing the free Xcode app development IDE. The IDE is an integrated development environment much like Visual Studio, Eclipse and others. Code is Objective C or Swift, while I recommend Objective C as much of the code that's out there is in Objective C. However, Swift is easy to learn and based on (but not exactly like) modern scripting languages. Then, search for tutorials on app development. Many are out there, and you can learn the basics to get started. What you do beyond that, is up to your time and effort that you commit. 

National Flea Awareness Month Starts in April

Throughout the month of April, beginning on April 1st, there is something about national flea awareness month. Dogs will be flown in trained to sniff out the common cat flea, which is typically what is found on both dogs and cats. These are no ordinary dogs. These are robotic dogs, with nanotechnology olfactory chips embedded in their noses. Robodogs, if you will, are the latest rage. Once taken out of their crate, they come fully charged and ready for their flea-seeking adventures.
April 1st, is of course, April Fool's Day. If you receive a flyer or brochure before then, and you would like your house or hotel checked for fleas, contact the National Flea Awareness Association by filling out their form and mailing it. No stamp is included, but it is required for proper delivery. Lucky winners will receive a visit from a skilled robodog operator who will scour their residence or (if hotel owner) a vacant room. All fleas detected are vacuumed into the robodog's collection bag and shipped off to the Analysis Center, at an undisclosed location. "Basically, it's a win-win situation," says the director, who chose not to have his name published. "Whoever win's a visit from the robodog, gets a free flea vacuum; we get several baggies of fleas to place in our flea farm." When asked about the flea farm, the director laughed and said, "It's an amusement park for fleas, complete with little flea-sized merry go rounds and a volleyball court, as well as a high jump contest. We simply want to raise awareness of fleas, and solve two problems: a couple of flea-infested houses or hotel rooms, and bored fleas." Note that pets should be taken to another room while the robodog does its thing. Cats don't like the mechanical whining sound, and dogs often become irritable when the robodog doesn't respond to normal dog greeting cues. In any case, it all starts this April 1st, so stay tuned!