Eric Jacobsen Blog on DSPRelated.com
https://www.dsprelated.com/blogs-1/nf/Eric_Jacobsen.php
Eric Jacobsen Blog on DSPRelated.com
https://www.dsprelated.com/blogs-1/nf/Eric_Jacobsen.php
https://d23s79tivgl8me.cloudfront.net/user/profilepictures/28938.jpgen-USThu, 18 Apr 2024 10:50:27 +00001713437427Understanding and Implementing the Sliding DFT
https://www.dsprelated.com/showarticle/776.php
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 straightforward algorithm, and often the largest barrier to working in the frequency domain is the complexity or latency involved in the Fast Fourier...]]>Thu, 23 Apr 2015 20:10:04 +0000Eric JacobsenFrequency-Domain Periodicity and the Discrete Fourier Transform
https://www.dsprelated.com/showarticle/175.php
Introduction

Some of the better understood aspects of time-sampled systems are the limitations and requirements imposed by the Nyquist sampling theorem [1]. Somewhat less understood is the periodic nature of the spectra of sampled signals. This article provides some insights into sampling that not only explain the periodic nature of the sampled spectrum, but aliasing, bandlimited sampling,...]]>
Mon, 06 Aug 2012 21:51:40 +0000Eric JacobsenTime-Domain Periodicity and the Discrete Fourier Transform
https://www.dsprelated.com/showarticle/174.php
Introduction

The Discrete Fourier Transform (DFT) and it's fast-algorithm implementation, the Fast Fourier Transform (FFT), are fundamental tools for processing and analysis of digital signals. While the continuous Fourier Transform and its inverse integrate over all time from minus infinity to plus infinity, and all frequencies from minus infinity to plus infinity, practical application of...]]>
Fri, 13 Jul 2012 14:52:35 +0000Eric JacobsenUnderstanding and Relating E<sub>b</sub>/N<sub>o</sub>, SNR, and other Power Efficiency Metrics
https://www.dsprelated.com/showarticle/168.php
Introduction

Evaluating the performance of communication systems, and wireless systems in particular, usually involves quantifying some performance metric as a function of Signal-to-Noise-Ratio (SNR) or some similar measurement. Many systems require performance evaluation in multipath channels, some in Doppler conditions and other impairments related to mobility. Some have interference...]]>
Tue, 29 May 2012 19:09:37 +0000Eric JacobsenSome Observations on Comparing Efficiency in Communication Systems
https://www.dsprelated.com/showarticle/136.php
Engineering is usually about managing efficiencies of one sort or another. One of my favorite working definitions of an engineer says, "An engineer is somebody who can do for a nickel what any damn fool can do for a dollar." In that case, the implication is that the cost is one of the characteristics being optimized. But cost isn't always the main efficiency metric, or at least...]]>Thu, 17 Mar 2011 13:08:32 +0000Eric JacobsenFrequency Dependence in Free Space Propagation
https://www.dsprelated.com/showarticle/62.php
Introduction

It seems to be fairly common knowledge, even among practicing professionals, that the efficiency of propagation of wireless signals is frequency dependent. Generally it is believed that lower frequencies are desirable since pathloss effects will be less than they would be at higher frequencies. As evidence of this, the Friis Transmission Equation[i]...]]>
Wed, 14 May 2008 23:59:33 +0000Eric JacobsenPulse Shaping in Single-Carrier Communication Systems
https://www.dsprelated.com/showarticle/60.php
Some common conceptual hurdles for beginning communications engineers have to do with "Pulse Shaping" or the closely-related, even synonymous, topics of "matched filtering", "Nyquist filtering", "Nyquist pulse", "pulse filtering", "spectral shaping", etc. Some of the confusion comes from the use of terms like "matched filter" which has a broader meaning in the more general field of signal...]]>Thu, 10 Apr 2008 16:56:41 +0000Eric JacobsenHandling Spectral Inversion in Baseband Processing
https://www.dsprelated.com/showarticle/51.php
The problem of "spectral inversion" comes up fairly frequently in the context of signal processing for communication systems. In short, "spectral inversion" is the reversal of the orientation of the signal bandwidth with respect to the carrier frequency. Rick Lyons' article on "Spectral Flipping" at http://www.dsprelated.com/showarticle/37.php discusses methods of handling the inversion (as...]]>Mon, 11 Feb 2008 15:16:16 +0000Eric Jacobsen