Wednesday, May 19, 2010

Intro to Fourier Transforms...

Way back when, shortly after the lava cooled enough to form a solid surface on the Earth, I was making my first explorations into digital signal processing.  With a friend, I was trying to design a better radio teletype (RTTY) modem, and I had the radical notion that a computer might do a better job at it than a collection of op amps, capacitors, resistors, and a bunch of solder.  But of course I had no idea how to go about it.

In the course of some reading, I came across the notion of Fourier Transforms, and in particular the “Fast Fourier Transform” (a software technique) – and off I went into what was the first of many explorations using mathematics to solve problems.  I am living proof that it is possible to do useful work with these techniques even though I am far from expert in the mathematics.  There are lots of engineers like me in this regard, and fortunately for us explanations like this exist for many mathematical tools.

The RTTY problem?  Well, it turned out that the Fast Fourier Transform was in fact a great tool for making a RTTY modem – but there was one little teensy problem.  With the hottest microcomputer of the day (a blazingly fast 4 MHz Z-80), the mathematics required took about 1000 times longer than realtime.  In other words, to analyze and provide results for 1 second of RTTY signal took about 1000 seconds of computer time.  My idea was good, but the hardware of the day was woefully inadequate.  Today's computers could easily do hundreds of them at the same time – and naturally today you can buy an RTTY modem (for under $100!) that works on the same principle that I was trying to use.

Oh, well...

1 comment:

  1. These type of blogs are very much appreciated by maths lovers,I think maths require more practice than other subject so students should study hard and do practice with problems.

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