Radio Apocalypse: Meteor Burst Communications

The world’s militaries have always been at the forefront of communications technology. From trumpets and drums to signal flags and semaphores, anything that allows a military commander to relay orders to troops in the field quickly or call for reinforcements was quickly seized upon and optimized. So once radio was invented, it’s little wonder how quickly military commanders capitalized on it for field communications.

Radiotelegraph systems began showing up as early as the First World War, but World War II was the first real radio war, with every belligerent taking full advantage of the latest radio technology. Chief among these developments was the ability of signals in the high-frequency (HF) bands to reflect off the ionosphere and propagate around the world, an important capability when prosecuting a global war.

But not long after, in the less kinetic but equally dangerous Cold War period, military planners began to see the need to move more information around than HF radio could support while still being able to do it over the horizon. What they needed was the higher bandwidth of the higher frequencies, but to somehow bend the signals around the curvature of the Earth. What they came up with was a fascinating application of practical physics: meteor burst communications.

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What’s In A Washer?

Some things are so common you forget about them. How often do you think about an ordinary resistor, for example? Yet if you have a bad resistor, you’ll find it can be a big problem. Plus, how can you really understand electronics if you don’t know all the subtle details of a resistor? In the mechanical world, you could make the same arguments about the washer, and [New Mind] is ready to explain the history and the gory details of using washers in a recent video that you can see below.

The simple answer is that washers allow a bolt to fit in a hole otherwise too large, but that’s only a small part of the story. Technically, what you are really doing is distributing the load of a threaded fastener. However, washers can also act as spacers or springs. Some washers can lock, and some indicate various things like wear or preloading conditions.

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Rebooting An 1973 Art Installation Running On A Nova

Electronics-based art installations are often fleeting and specific things that only a select few people who are in the right place or time get to experience before they are lost to the ravages of ‘progress.’ So it’s wonderful to find a dedicated son who has recreated his father’s 1973 art installation, showing it to the world in a miniature form. The network-iv-rebooted project is a recreation of an installation once housed within a departure lounge in terminal C of Seattle-Tacoma airport.

You can do a lot with a ‘pi and a fistful of Teensies!

The original unit comprises an array of 1024 GE R6A neon lamps, controlled from a Data General Nova 1210 minicomputer. A bank of three analog synthesizers also drove into no fewer than 32 resonators. An 8×8 array of input switches was the only user-facing input. The switches were mounted to a floor-standing pedestal facing the display.

For the re-creation, the neon lamps were replaced with 16×16 WS2811 LED modules, driven via a Teensy 4.0 using the OctoWS2811 library. The display Teensy is controlled from a Raspberry Pi 4, hooked up as a virtual serial device over USB. A second Teensy (you can’t have too many Teensies!) is responsible for scanning a miniature 8×8 push button array as well as running a simulation of the original sound synthesis setup. Audio is pushed out of the Teensy using a PT8211 I2S audio DAC, before driving a final audio power amp.

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