http://www.dsprelated.com en-us Copyright 2011, DSPRelated.com. http://www.dsprelated.com/new/images/logo.jpg http://www.dsprelated.com 267 48 This blog describes a technique to reduce the effects of spectral leakage when using the discrete Fourier transform (DFT). In late April 2012 there was a thread on the comp.dsp newsgroup discussing ways to reduce the spectral leakage problem encountered when using the DFT. One post in that thread caught my eye [1]. That post referred to a website presenting a paper describing a DFT leakage meth... read more]]> Wed, 23 May 2012 14:49:21 -0400 DSPRelated.com last blog entries Introduction The following is an introduction on how to design an infinite impulse response (IIR) filters using the Python scipy.signal package.  This post, mainly, covers how to use the scipy.signal package and is not a thorough introduction to IIR filter design.  For complete coverage of IIR filter design and structure see one of the references. Filter Specification Before pro... read more]]> Sun, 13 May 2012 22:30:06 -0400 DSPRelated.com last blog entries Summary: A floating point model for a CIC decimator, including the frequency response. Description: A CIC filter relies on a peculiarity of its fixed-point implementation: Normal operation involves repeated internal overflows that have no effect to the output signal, as they cancel in the following stage. One way to put it intuitively is that only the speed (and rate of change) of every little... read more]]> Tue, 08 May 2012 09:48:06 -0400 DSPRelated.com last blog entries   First, I think ipython is great. I use it daily and always have an ipython terminal open.  But just recently, I was showing off the ipython 0.12 notebook and in the process created a lengthy example while demonstrating the cool features of the ipython notebook.  The example included LaTeX equations, plots, etc.  Since the notebook session was on something of relevance I ... read more]]> Tue, 01 May 2012 22:16:34 -0400 DSPRelated.com last blog entries Do you remember the probability course you took in undergrad? If you were like me, you would consider it one of those courses that you get out of confused. But maybe a time will come where you regret skipping class because of the lecturer's persisting attempts to scare you with mathematical involved nomenclature.As you might have guessed, I had this moment few months back where I had to go deep in... read more]]> Mon, 26 Mar 2012 18:09:02 -0400 DSPRelated.com last blog entries If you have ever studied or designed a cascaded integrator-comb (CIC) lowpass filter then surely you've read Eugene Hogenauer's seminal 1981 IEEE paper where he first introduced the CIC filter to the signal processing world [1]. As it turns out, Hogenauer's famous paper was not the first formal document describing and proposing CIC filters. Here's the story. In the Fall of 1979 Eugene Hogenauer... read more]]> Mon, 20 Feb 2012 08:52:38 -0500 DSPRelated.com last blog entries There has been some chatter on the scipy-dev mailing list lately about enhancing the scipy.signal package.  Unfortunately, there seems to be a split.  Some are going off and starting a new package scikit-signal.  The original developer, Travis Oliphant, appears to have strong interest in seeing the scipy.signal evovle.  If you are interested in signal processing you should chec... read more]]> Thu, 19 Jan 2012 08:01:01 -0500 DSPRelated.com last blog entries Full Disclosure: The publisher of this book, PACKT, was soliciting reviewers.  I volunteered to review the book and the publisher sent me an e-version of the book. Introduction The following is a review of "Numpy 1.5 Beginner's Guide", "Learn by doing: less theory, more results" by Ivan Idris.  As the title suggests this book is for a beginner.  Either someone who is new to nu... read more]]> Sat, 07 Jan 2012 16:08:22 -0500 DSPRelated.com last blog entries This article is the documentation to a code snippet that originated from a discussion on comp.dsp. The task is to design a root-raised cosine filter with a rolloff of a=0.15 that interpolates to 64x the symbol rate at the input. The code snippet shows a solution that is relatively straightforward to design and achieves reasonably good efficiency using only FIR filters. Motivation: “simpl... read more]]> Mon, 26 Dec 2011 18:33:51 -0500 DSPRelated.com last blog entries There are two code snippets associated with this blog post: Flat-Top Windowing Function for the Accurate Measurement of a Sinusoid's Peak Amplitude Based on FFT Data and Testing the Flat-Top Windowing Function This blog discusses an accurate method of estimating time-domain sinewave peak amplitudes based on fast Fourier transform (FFT) data. Such an operation sounds simple, but the scallopin... read more]]> Wed, 14 Dec 2011 08:56:48 -0500 DSPRelated.com last blog entries This article is also available in PDF format There are so many different time- and frequency-domain methods for generating complex baseband and analytic bandpass signals that I had trouble keeping those techniques straight in my mind. Thus, for my own benefit, I created a kind of reference table showing those methods. I present that table for your viewing pleasure in this blog. For clarity, I... read more]]> Wed, 02 Nov 2011 09:32:26 -0400 DSPRelated.com last blog entries Every engineer who took a basic signal processing course is familiar with the Gibbs phenomenon, however, not all know why it occurs, I mean really why! The answer lies in the mathematical background that is almost always skipped in signal processing courses. Moreover, from my experience at least, many textbooks present the theory, e.g. the Fourier transform, as infallible and no discussion of the... read more]]> Tue, 04 Oct 2011 06:03:15 -0400 DSPRelated.com last blog entries Everyone has their favorite computing platform, regardless if it is Matlab, Octave, Scilab, Mathematica, Mathcad, etc.  I have been using Python and the common numerical and scientific packages available.  Personally, I have found this to be very useful in my work.  Lately there has been some chatter on speeding up Python. From another project I follow, MyHDL, I was introduced to t... read more]]> Sat, 17 Sep 2011 01:28:17 -0400 DSPRelated.com last blog entries I found this website that contains loads of free, high quality, ebooks and journals as well. There is 176 ebooks under electrical engineering heading. I found books suitable for engineers, researcher, and hobbiest as well.   Here is the link for it: http://www.intechopen.com/   To be more useful here are few MATLAB books: http://www.intechopen.com/books/show/title/applications-of-m... read more]]> Tue, 13 Sep 2011 14:00:02 -0400 DSPRelated.com last blog entries Bank-switched Farrow resampler Summary A modification of the Farrow structure with reduced computational complexity.Compared to a conventional design, the impulse response is broken into a higher number of segments. Interpolation accuracy is achieved with a lower polynomial order, requiring fewer multiplications per output sample at the expense of a higher overall number of coefficients. Exampl... read more]]> Sat, 13 Aug 2011 07:19:36 -0400 DSPRelated.com last blog entries