by Barry Van Veen I am often asked, "What do careers in signal processing involve?" My answer is, "Almost anything." Signal processing has invaded every aspect of our daily lives. Medical diagnostics and treatment, transportation, weather forecasting, environmental monitoring, and personal electronics, e.g., cell phones, are a few of the everyday places we use signal processing. The Read More
Aliasing in Movies: Levitating Helicopters and Wheels Rotating Contrary to Motion
by Barry Van Veen Movies consist of individual images that are recorded or played back at a certain rate. Thus each pixel in the movie is sampled. A common frame rate for movies is 30 frames per second, which means that each pixel is sampled at 30 Hz. This is sufficiently fast that humans do Read More
Learn Better: Science Shows You How to Succeed
Barry Van Veen The fields of neuroscience and cognitive psychology have now established very clear understandings of effective study habits. It turns out that widely used, passive techniques like highlighting and rereading a text (or re-watching a lecture video) are actually counterproductive. They may increase your familiarity, but do not improve your ability to apply Read More
Concussion and AllSignalProcessing
This post is not about the recent movie on brain damage discovered in (American) football players by Dr. Bennet Omalu. It is about my own recent journey. I rarely share personal information over the internet. However, I want to give those of you who follow AllSignalProcessing.com some context for my reduced level of activity on the site over the past Read More
Aliasing of Signals - Identity Theft in the Frequency Domain
by Barry Van Veen Earlier this year someone filed an income tax return using my identity. The topic of this blog post is aliasing, not tax fraud, although the concepts are similar. Aliasing in signal processing is when a sinusoid of one frequency takes on the appearance or identity of a different frequency sinusoid. Read More
Estimation of the Amplitude and Phase of Sinusoids in Noise
by Barry Van Veen In the previous post we developed a method for estimating the amplitude and phase of sinusoids from data samples assuming the frequencies are known. This method applies to sinusoids with arbitrary frequencies. The approach we used to develop the estimator was to convert the amplitude and phase of each sinusoid into Read More
Estimation of the Amplitude and Phase of Sinusoids
by Barry Van Veen Sinusoids play an important role in describing physical phenomena. In some problems the amplitude and phase of data involving a sum of sinusoids is of interest. This post addresses the problem of estimating the amplitude and phase assuming the frequencies of the sinusoids are known. Estimation of the amplitude and phase Read More
Nonlinear Systems in Amplification of Signals
by Barry Van Veen In the previous post we discussed the use of nonlinear systems for enhancing faint details in digital photographs of the night sky. Another application where nonlinear systems are frequently encountered is amplification of signals, the topic of this post. Nonlinear Systems in Amplification An amplifier is an analog system that takes Read More
Nonlinear Systems: An Important Tool for Astrophotography
by Barry Van Veen A great deal of signal processing is concerned with linear systems. The mathematics for analyzing linear systems are very powerful. However, in some applications nonlinear systems are a very useful signal processing tool. One such application is in astrophotography, where a nonlinear system is used to make faint details more visible in images Read More
Very Low Frequency Filtering: Do It Right Using Downsampling
by Barry Van Veen Interest in signals that are a very small fraction of the sampling frequency is increasingly common due to the widespread availability of high speed digital-to-analog converters. For example, infra-slow oscillations (0.01 - 0.1 Hz) are sometimes of interest in electroencephalography (EEG) for understanding large-scale cortical organization. EEG signals are often sampled Read More
Selecting a Filter: Which One?
by Barry Van Veen I am frequently asked, "Which is the best filter?" There are infinite impulse response (IIR) and finite impulse response (FIR) filters, Butterworth, Chebyshev I and II, elliptic, and minimax designs. Then there are at least a dozen different windows that can be used with the window design method. In light of Read More
Convolution of Signals: Why?
The Merriam-Webster dictionary defines convolution as "something that is very complicated and difficult to understand" and "a form or shape that is folded in curved or tortuous windings." These are not signal processing definitions, but certainly describe the impression that students often receive when they first encounter the mathematical definition of convolution, typically in a Read More
Fourier Methods: Why So Prominent?
by Barry Van Veen You don't have to be around signal processing very long before you realize that Fourier methods play a huge role in the field. Newcomers often wonder why they are so important. There are several very good reasons for the prominence of Fourier methods in signal processing. They offer substantial intuition, naturally follow Read More
Discrete-Time Frequency: Avoid Confusion
by Barry Van Veen Frequency is a pervasive concept in signal processing. New comers to signal processing are often comfortable with the idea of frequency for continuous-time signals. For example, they may know that frequency is measured in units of Hertz (Hz) or cycles per second. Many are aware that the range of human hearing is from 20 Hz at Read More
Brain Network Models
by Barry Van Veen One of the scientific frontiers of our time is understanding the human brain. The U.S. National Academy of Engineering declared reverse engineering the brain to be an engineering grand challenge. U.S. President Barak Obama recently inaugurated the BRAIN initiative to "revolutionize our understanding of the human mind." Similar initiatives are being pursued by governments Read More