Understanding convolution is central to understanding filtering, the Discrete Fourier Transform, and other important DSP operations.  In this tutorial, R. C. Kim explains convolution using a visual, intuitive, step-by-step method, and relates it to filtering and the DFT.

In this tutorial, Richard G. Lyons, author of the best-selling DSP book Understanding Digital Signal Processing, discusses the estimation of time-domain sinewave peak amplitudes based on fast Fourier transform (FFT) data.

Multipath distortion is a common problem in many DSP-based data transmission systems.  Here, Neil Robertson shows how to model multipath channels using complex-coefficient FIR filters. 

Many DSP systems use composite signals consisting of a sum of sinusoids of the same frequency, often a sine and cosine. In this tutorial, Richard G. Lyons, author of the best-selling DSP book Understanding Digital Signal Processing, thoroughly covers this important DSP topic by explaining and deriving formulas for the sum of two sinusoids of the same frequency.

Readers of my previous blog entry "What Light Through Yonder Flashlight Shakes?" have asked for details about the science project that caused my son and I to look into shake flashlights in the first place. Here goes.

I recently helped a lad put together a school science project that involved the idea of using "shake flashlights" as a power source.  The idea seemed like a good one when he first proposed it.  But when we began to implement it we immediately ran into a quite unexpected problem: it's impossible to find shake flashlights in retail stores.

I ran into Gall's Law recently, which states: "A complex system that works is invariably found to have evolved from a simple system that worked. The inverse proposition also appears to be true: A complex system designed from scratch never works and cannot be made to work. You have to start over, beginning with a working simple system."