Two Good Ham Radio-ish Academic Journal Articles

I do a lot of work with maps of the F2 layer of the ionosphere. I found two good articles, (so far), this week that I wanted to pass along.

The first has to do with the ionosphere itself and how signals propagate through it. The Department of Commerce book, (here's the older 1948 version), on the ionosphere that I frequently quote and more frequently use cites a number of formula and diagrams without a whole lot of explanation. I finally checked out the references this week and found that much of the information I use from that book—including the figure below—comes from this more information-dense paper by Newbern Smith.

The second paper hits on the topic of quaternions—one of my perrenial favorites—in relation to rotations in video games. How did I find it? Using ChatGPT to prototype mapping apps again, of course. I wanted to find what squares on a spherical map of the Earth a QSO path traveled through.

ChatGPT suggested susing something called a slerp. Wondering if this was completely made up, I looked up the term and happened upon this paper by Ken Shoemake of PARC circa 1986. I tested out the code produced by ChatGPT, and sure enough, slerps are a viable solution.

I intend to spend more time with slerps in the near future. Quaternions are the super-cool vector like things invented by William Rowan Hamilton in 1843 and then ripped to shreds by Heaviside, Helmholtz, and Gibbs a few decades later in favor of vectors and vector calculus.

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