Apply a Filter Twice for Greatly Improved Performance

Figure 3. Impulse response of the filter of Figure 1 convolved with itself.

Say that you have implemented a low-pass FIR filter with the correct cut-off frequency and transition band, but that you are not quite happy with the suppression of frequencies in the stop band. A straightforward trick to put in your toolbox is that you can double the suppression by…

Tom Mon, 02/26/2018 - 13:01
The Phase Response of a Filter

Figure 2. Frequency (left) and phase (right) response of a moving-average filter.

The article Why use Symmetrical FIR Filters with an Odd Length? mentiones that symmetrical FIR filters are linear phase. In this follow-up article, I simply want to show you what the phase response of these filters actually looks like…

Tom Thu, 02/08/2018 - 17:39 in 2017

This article is a wrap-up of what happened on in 2017.

Tom Sun, 12/31/2017 - 15:42



Figure 1. Artist’s impression of ʻOumuamua [image: ESO/M. Kornmesser]

ʻOumuamua is the first ever interstellar body that was observed while it passed through our solar system, which makes it a really cool object. Hundreds of thousands of asteroids and comets have been observed, but all of them originated from within our own solar system. It was known that…

Tom Sat, 12/23/2017 - 17:11


What is a Hadamard Matrix?

A Hadamard matrix is a matrix with all elements equal to \(+1\) or \(-1\), and for which the rows are mutually orthogonal. If you pick two rows from the matrix and write it as vectors \(\bf x\) and \(\bf y\), then these are orthogonal if…

Tom Wed, 12/06/2017 - 21:56

What is jerk? Jerk is to acceleration as acceleration is to velocity. And, acceleration is to velocity as velocity is to position. So let’s start there. The instantaneous velocity at which you travel tells you…

Tom Mon, 11/20/2017 - 19:34