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 […]

# Blog

## 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 […]

## 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 […]

## 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 […]