This is the personal site of Tom Roelandts. I’m trying to whet your appetite for science with this thing. My education and interests show through, of course, since I focus on stuff that I feel confident writing about. The site used to be solely about the photos, and I still think the thumbnails page is rather cute, but the emphasis has clearly shifted towards the articles lately.

If You See a Fireball, Please Report It

Figure 2. Sightings of a single fireball that appeared on 2015-03-15.

If you have ever seen a fireball, which is an unusually bright meteor (or shooting star), then you know that they can be very impressive. But did you also know that reporting your observation can help to further science? Fireballs, and meteors in general, are like… read more

Submitted on 21 March 2015

Normalized Frequency For The Win

Figure 1. Low-pass filter response with normalized frequency.

Frequency response plots are often shown with normalized frequency on the X-axis. This sometimes confuses people. The normalized frequency is computed by dividing the true frequency by the sample rate. Hence, the sample rate itself has… read more

Submitted on 3 March 2015

Why Clipping Should Be Avoided

Figure 2. Clipped sine.

Before you can digitally process an analog (i.e., real-world) signal, you have to convert it to a digital form by sampling it. A very important aspect of this conversion is that you should avoid clipping the original signal. Clipping happens when… read more

Submitted on 16 February 2015

Filter Designer

After explaining how to create windowed-sinc low-pass and high-pass filters, I have made a tool that allows you to create your own custom versions of these filters, and download the resulting filter coefficients. Go to the tool. At this time, the tool is limited to the (very basic) design method from the mentioned articles, but that’ll change in the future! read more

Submitted on 10 January 2015

New Horizons

New Horizons at Pluto [image: JHUAPL/SwRI]

After mentioning Rosetta in June, there is another deep space mission that I want to bring to your attention. The final preparations for the flyby of Pluto by the New Horizons spacecraft have started. New Horizons will be… read more


Submitted on 14 December 2014

How Does Amplitude Modulation Work?

Figure 3. AM-modulated carrier.

Using modulation in radio communications is unavoidable. The simplest modulation technique is Amplitude Modulation (AM), where the amplitude of a carrier is varied according to the message that is to be transmitted. A carrier is… read more

Submitted on 2 November 2014


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