Hackaday Links: March 14, 2021

It’ll be Pi Day when this article goes live, at least for approximately half the globe west of the prime meridian. We always enjoy Pi Day, not least for the excuse to enjoy pie and other disc-shaped foods. It’s also cool to ponder the mysteries of a transcendental number, which usually get a good treatment by the math YouTube community. This year was no disappointment in this regard, as we found two good pi-related videos, both by Matt Parker over at Standup Maths. The first one deals with raising pi to the pi to the pi to the pi and how that may or may not result in an integer that’s tens of trillions of digits long. The second and more entertaining video is a collaboration with Steve Mould which aims to estimate the value of pi by measuring the volume of a molecular monolayer of oleic acid floating on water. The process was really interesting and the results were surprisingly accurate; this might make a good exercise to do with kids to show them what pi is all about.

Remember basic physics and first being exposed to the formula for universal gravitation? We sure do, and we remember thinking that it should be possible to calculate the force between us and our classmates. It is, of course, but actually measuring the attractive force would be another thing entirely. But researchers have done just that, using objects substantially smaller than the average high school student: two 2-mm gold balls. The apparatus the Austrian researchers built used 90-milligram gold balls, one stationary and one on a suspended arm. The acceleration between the two moves the suspended ball, which pivots a mirror attached to the arm to deflect a laser beam. That they were able to tease a signal from the background noise of electrostatic, seismic, and hydrodynamic forces is quite a technical feat.

We noticed a lot of interest in the Antikythera mechanism this week, which was apparently caused by the announcement of the first-ever complete computational model of the ancient device’s inner workings. The team from University College London used all the available data gleaned from the 82 known fragments of the mechanism to produce a working model of the mechanism in software. This in turn was used to create some wonderful CGI animations of the mechanism at work — this video is well worth the half-hour it takes to watch. The UCL team says they’re now at work building a replica of the mechanism using modern techniques. One of the team says he has some doubts that ancient construction methods could have resulted in some of the finer pieces of the mechanism, like the concentric axles needed for some parts. We think our friend Clickspring might have something to say about that, as he seems to be doing pretty well building his replica using nothing but tools and methods that were available to the original maker. And by doing so, he managed to discern a previously unknown feature of the mechanism.

We got a tip recently that JOGL, or Just One Giant Lab, is offering microgrants for open-source science projects aimed at tackling the problems of COVID-19. The grants are for 4,000€ and require a minimal application and reporting process. The window for application is closing, though — March 21 is the deadline. If you’ve got an open-source COVID-19 project that could benefit from a cash infusion to bring to fruition, this might be your chance.

And finally, we stumbled across a video highlighting some of the darker aspects of amateur radio, particularly those who go through tremendous expense and effort just to be a pain in the ass. The story centers around the Mt. Diablo repeater, an amateur radio repeater located in California. Apparently someone took offense at the topics of conversation on the machine, and deployed what they called the “Annoy-o-Tron” to express their displeasure. The device consisted of a Baofeng transceiver, a cheap MP3 player loaded with obnoxious content, and a battery. Encased in epoxy resin and concrete inside a plastic ammo can, the jammer lugged the beast up a hill 20 miles (32 km) from the repeater, trained a simple Yagi antenna toward the site, and walked away. It lasted for three days and while the amateurs complained about the misuse of their repeater, they apparently didn’t do a thing about it. The jammer was retrieved six weeks after the fact and hasn’t been heard from since.

15 thoughts on “Hackaday Links: March 14, 2021

    1. Dates… 3-14-yyyy, 14-03-yyyy, yyyy-03-14… a mess! I think the one thing that matters is making people think about PI. Aaaaaand I’m not against a TAU day at all! Just read the bar as the straightened circumference and the count of the legs below it as the divisor. A 3, 4, 5, … legged symbol then would give … ?

      And on Jul-22 I’ll just be approximating thinking about PI!

      And where is the calender for 355/113?
      Hmmm … we need to find more exoplanets and data about them!
      There has to be one with a 355 days long year!
      Just search harder…

  1. One person didn’t like what other people were talking about, so he attacked their free speech.

    A better plan might have been to just stop listening to the other people. Attacking others for doing [legal] things you don’t like and that don’t impact you is immoral.

    1. Free speech must always be defended, not just against radio jammers but against governments too. Everyone has a right to speak, to protest for that matter, regardless of what the wider situation might be at the time, and we mst protect that right even for those saying and protesting things we do not agree with. The alternative is a fall into totalitarian collectivism.

    2. People’s disgusting politics (right *OR* left) have absolutely NO place on ham radio. It’s guaranteed to cause problems, so why does one side insist on excluding the other by engaging in it? Don’t start nothing, won’t BE nothing.

  2. This story about jamming may be recent, but it isn’t a new thing. Fifty years ago there were “repeater wars”, and in the eighties or nineties I did read an article about someone setting up a jammer. It was hidden, and they had to use direction finding to locate it, and something about it transmitting based on something, so it wasn’t always transmitting, which made it harder to find, but also meant it lasted longer battery wise.

    1. Yeah, the Annoy-O-Tron design was pretty brute-force — the MP3 player was set up to play continuously, and the tracks were either random annoying sounds or silence. The Baofeng was set up with VOX so it would transmit only when a track with audio came around. And it was 20 miles away, so it wasn’t hard to blow it off the repeater with a closer, more powerful radio. The builder seems to have put more effort into not being found than designing an effective jammer.

  3. Free speech must always be defended, not just against radio jammers but against governments too. Everyone has a right to speak, to protest for that matter, regardless of what the wider situation might be at the time, and we mst protect that right even for those saying and protesting things we do not agree with. The alternative is a fall into totalitarian collectivism.

    1. This was a case of malicious interference. I suspect it’s against some law, but it’s definitely against the moral code of ham radio.

      But I’d point out that same moral code prohibits some of the things that might get reacted to.

      So “free speech” is limited in ham radio.

      It is possible that someone said something that got a reaction, or it could just ve someone hogging the repeater.

      The deliberage jamming is tge issue here.

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