What Do You Know About DSP?

Digital signal processing is not one of those subjects that older engineers learned in college.  If you learned it at all, you did so with books, seminars and maybe a colleague.  So many of you never learned it, period.  But of course you all know what it is.  Awareness does not mean you can design with it, but at least you can appreciate how something so complex can become so commonplace.  DSP has become a common feature in most electronic products today.  In fact, it is difficult to think of a modern product that does not use DSP. It is in TV sets, smartphones, iPods, any digital radio, medical equipment, and others.  Help me out here.  Name one that does not use it.  Maybe a guitar amplifier, but then again I could be wrong about even that.

I first learned of DSP in the 1960’s when we processed geophysical seismic ground readings from geophones recorded on magnetic tape to find specific signal shapes and frequencies.  This was just after Cooley-Tukey put forth their famous fast Fourier transform (FFT) algorithm.  The processing was done on an IBM 7090 and the output was a long fan fold paper printout.  It was very time consuming but it worked.  It was fine for research but not ok for practical signal processing.  Today, geophysical signals are routinely processed in DSP on fast PCs.  No big deal.

I learned DSP with a mix of books, manufacturer’s literature and today’s Internet resources.  I must have a dozen books on DSP.  Some are just incomprehensible academic tomes while others do get to the practical side of DSP.  It took this mix of books to make things clear.  I still have not found the ideal book but some come close.

Just recently I came across a new book that is worth looking into if you are just learning DSP on your own.  It is The Essential Guide to Digital Signal Processing by Richard G. Lyons and D. Lee Fugal (Prentice Hall).  This book does a great job of detailing analog signals, sampling, spectra, and related topics.  These are the real basics of DSP and are often misunderstood.  Some DSP books just assume you know this already.  Many do not and I certainly was not that versed in those fundamentals when I started.

The book goes on the give several examples of how FFT works and digital filters.  What the book does not provide is details on algorithms for specific processes, but it does a fine job of giving you the concepts that prepares you for the more advanced books.  If you are starting from scratch, read this book first then go on to some more advanced books.

Author Richard Lyons also has a more advanced book called Understanding Digital Signal Processing (Prentice Hall, 2001) when you are ready for the gory details.  Other books that really helped me are Digital Signal Processing: A Hands-On Approach by Charles Schuler and Mahesh Chugani (McGraw Hill, 2005), Digital Signal Processing Technology by Doug Smith (American Radio Relay League, 2001), and Practical Digital Signal Processing for Engineers and Technicians by Edmund Lai (Newnes/Elsevier, 2004).

DSP was initially done on large fast computers.  Then in the 1980s we got DSP microcontrollers like those from Texas Instruments and Freescale (Motorola).  Today PC and smartphone micros are fast enough to run DSP.  Much of today’s DSP is done in an FPGA or in custom logic.

If you have not learned DSP yet, it is a great self education project with lots of resources.  What we really need is a cheap development kit so we can demo FFT spectrum analysis or try out different FIR or IIR filters.

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