Acoustic Camera Uses Many, Many Microphones

August 10, 2020 by Lewin Day 53 Comments

If you’re a human or other animal with two ears, you’ll probably find great utility in your ability to identify the direction of sounds in the world around you. Of course, this is really just a minimal starting point for such abilities. When [John Duffy] set out to build his acoustic camera, he chose to use ninety-six microphones to get the job done.

The acoustic camera works by having an array of microphones laid out in a prescribed grid. By measuring the timing and phase differences of signals appearing at each microphone, it’s possible to determine the location of sound sources in front of the array. The more microphones, the better the data.

[John] goes into detail as to how the project was achieved on the project blog. Outlining such struggles as assembly issues, he also shares information about how to effectively debug the array, and just how to effectively work with so many microphones at once. Particularly impressive is the video of [John] using the device to track a sound to its source. This technology has potential applications in industry for determining the location of compressed air leaks, for example.

Overall, it’s a university research project done right, with a great writeup of the final results. [John]’s project would serve well as a jumping off point for anyone trying to build something similar. Phased array techniques work in RF, too, as this MIT project demonstrates. Video after the break.

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The Weather Station At The Top Of The World

August 10, 2020 by Dan Maloney 14 Comments

The crown jewels of the Earth’s mountain ranges, the Himalayas, are unsurpassed in their beauty, their height, and their deadly attraction to adventurers, both professional and amateur. The gem of the Himalayas is, of course, Mount Everest, known as Sagarmatha to the Nepalis and Chomolungma to the Tibetans. At 8,848 meters (29,029 ft) — or more; it’s a geologically young mountain that’s still being thrust upward by tectonic activity — it’s a place so forbidding that as far as we know the summit was never visited until 1953, despite at least 30 years of previous attempts, many of which resulted in death.

The conquest of Everest remains a bucket list challenge for many adventurers, and despite advances in technology that have made the peak accessible to more people — or perhaps because of that — more than 300 corpses litter the mountain, testament to what can happen when you take the power of Mother Nature for granted.

To get better data on the goings-on at the Roof of the World, an expedition recently sought to install five weather stations across various points on the route up Mount Everest, including one at its very peak. The plan was challenging, both from a mountaineering perspective and in terms of the engineering required to build something that would be able to withstand some of the worst conditions on the planet, and to send valuable data back reliably. It didn’t all go exactly to plan, but it’s still a great story about the intersection of science and engineering.

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The Zero Terminal 3: A Pop-Out Keyboard Linux Computer In Your Pocket

August 10, 2020 by Jenny List 35 Comments

The mobile phone revolution has delivered us attractively packaged and convenient computing in our pockets, but without the easy hackability we like in our community. Meanwhile the advent of single board computers has given us affordable super-powerful hardware that can run a very capable GNU/Linux operating system and fulfill all our hackable computing needs. Combine the two though? Plenty have tried, few have succeeded in making something as slick as the former with the open power of the latter. Fine if you like your portable devices to have a cyberdeck vibe, but maybe not something you’d take into the boardrooom. Never fear though, for [N-O-D-E] have the solution, in version 3 of the Zero Terminal. It’s the ultimate in Raspberry Pi based handheld computing, and it resembles a slightly chunky mobile phone.

At its heart is a Waveshare OLED 5.5″ touch screen, on the back owhich is mounted a PCB that carries a USB hub and power circuitry. A Pi Zero is mounted directly to this, and a cleverly designed HDMI adapter board interfaces it to the display. The power board is a generic one, the one designed for the PCB proved difficult to hand solder. There’s a very smartly designed case to give it that mobile phone feel, and on the back are a set of sockets with all the relevant Pi connections. This opens the possibility of some exciting add-ons, the first of which is a sliding keyboard similar to those on early Android phones. The ‘board is based on a [Bobricius] design, though sadly isn’t quite working yet.

As you can see in the video below the break, this is about as slick a mobile Pi as it’s possible to get. [N-O-D-E], we want one. Just take our money!

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Unique Instrument Plucks Out Notes On A Ruler

August 10, 2020 by Dan Maloney 18 Comments

How does one describe the notes that come from a ruler that is anchored on one end and then plucked? The best word we can come up with is “wubulation”. So would that make this ruler-plucking synthesizer a “wubulator”? Or perhaps a “wubatron”?

Whatever we decide to call it, [Dmitry Morozov] dubbed it the RBS-20, or “ruler bass synth, 20-cm”, for the 20-cm stainless steel ruler that forms the heart of the instrument. The ruler is attached to a linear slide which varies the length of the sprung section. A pair of servos can pluck the free section of the ruler in two different places, providing notes in different registers, while another pair of servos control metal fingers that can damp the vibration, change the sustain, and alter the notes. There’s no resonator; the sounds are instead picked up by a piezo mic. Twelve keys on the base of the instrument can be programmed for various lengths, and an OLED display gives the musician feedback. The video below shows the instrument wubulating, and brings us back to those desktop jam sessions in our grade school days — at least until the rulers were confiscated.

We’ve covered a ton of similarly unique musical instruments before, like this hybrid synthesizer-violin, a symphony of soda bottles, and inexplicably, a leg guitar.

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