Exponential Smoothing with a Wrinkle

Cedron Dawg

Introduction This is an article to hopefully give a better understanding to the Discrete Fourier Transform (DFT) by providing a set of preprocessing filters to improve the resolution of the DFT. Because of the exponential nature of...

Discrete-Time PLLs, Part 1: Basics

Reza Ameli

In this series of tutorials on discrete-time PLLs we will be focusing on Phase-Locked Loops that can be implemented in discrete-time signal proessors such as FPGAs, DSPs and of course, MATLAB.

Analytic Signal


In communication theory and modulation theory we always deal with two phases: In-phase (I) and Quadrature-phase (Q). The question that I will discuss in this blog is that why we use two phases and not more.

Blogging Tutorial

Stephane Boucher

This article will be updated on a regular basis based on your questions and feedback. Creating a new blog post Make sure your are logged in Click on 'Create new blog post' Although the online editor works pretty well and...

Four Ways to Compute an Inverse FFT Using the Forward FFT Algorithm

Rick Lyons

If you need to compute inverse fast Fourier transforms (inverse FFTs) but you only have forward FFT software (or forward FFT FPGA cores) available to you, below are four ways to solve your problem. Preliminaries To define what we're...

Handy Online Simulation Tool Models Aliasing With Lowpass and Bandpass Sampling

Rick Lyons

Analog Devices Inc. has posted a neat software simulation tool on their corporate web site that graphically shows the aliasing effects of both lowpass and bandpass periodic sampling. This is a nice tutorial tool for beginners in DSP. The...

Ten Little Algorithms, Part 2: The Single-Pole Low-Pass Filter

Jason Sachs
1 comment

Other articles in this series: Part 1: Russian Peasant Multiplication Part 2: The Single-Pole Low-Pass Filter Part 3: Welford’s Method (And Friends) Part 4: Topological Sort I’m writing this article in a room with a bunch of...

Understanding and Implementing the Sliding DFT

Eric Jacobsen

Introduction In many applications the detection or processing of signals in the frequency domain offers an advantage over performing the same task in the time-domain.   Sometimes the advantage is just a simpler or more conceptually...

Why Time-Domain Zero Stuffing Produces Multiple Frequency-Domain Spectral Images

Rick Lyons

This blog explains why, in the process of time-domain interpolation (sample rate increase), zero stuffing a time sequence with zero-valued samples produces an increased-length time sequence whose spectrum contains replications of the original...

The Exponential Nature of the Complex Unit Circle

Cedron Dawg

Introduction This is an article to hopefully give an understanding to Euler's magnificent equation: $$ e^{i\theta} = cos( \theta ) + i \cdot sin( \theta ) $$ This equation is usually proved using the Taylor series expansion for the given...