Building A Sound Camera For Under $400

October 10, 2024 by Lewin Day 22 Comments

[Benn Jordan] had an idea. He’d heard of motion amplification technology, where cameras are used to capture tiny vibrations in machinery and then visually amplify it for engineering analysis. This is typically the preserve of high-end industrial equipment, but [Benn] wondered if it really had to be this way. Armed with a modern 4K smartphone camera and the right analysis techniques, could he visually capture sound?

The video first explores commercially available “acoustic cameras” which are primarily sold business-to-business at incredibly high prices. However, [Benn] suspected he could build something similar on the cheap. He started out with a 16-channel microphone that streams over USB for just $275, sourced from MiniDSP, and paired it with a Raspberry Pi 5 running the acoular framework for acoustic beamforming. Acoular analyses multichannel audio and visualizes them so you can locate sound sources. He added a 1080p camera, and soon enough, was able to overlay sound location data over the video stream. He was able to locate a hawk in a tree using this technique, which was pretty cool, and the total rig came in somewhere under $400.

The rest of the video covers other sound-camera techniques—vibration detection, the aforementioned motion amplification, and some neat biometric techniques. It turns out your webcam can probably detect your heart rate, for example.

It’s a great video that illuminates just what you can achieve with modern sound and video capture. Think SIGGRAPH-level stuff, but in a form you can digest over your lunchbreak. Video after the break.

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Supercon 2023: Receiving Microwave Signals From Deep-Space Probes

October 10, 2024 by Lewin Day 5 Comments

Here’s the thing about radio signals. There is wild and interesting stuff just getting beamed around all over the place. Phrased another way, there are beautiful signals everywhere for those with ears to listen. We go about our lives oblivious to most of them, but some dedicate their time to teasing out and capturing these transmissions.

David Prutchi is one such person. He’s a ham radio enthusiast that dabbles in receiving microwave signals sent from probes in deep space. What’s even better is that he came down to Supercon 2023 to tell us all about how it’s done!

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Photochromic Dye Makes Up This Novel Optical Memristor

October 10, 2024 by Dan Maloney 20 Comments

Despite being much in the zeitgeist lately, we have to confess to still being a bit foggy about exactly what memristors are. The “mem” part of their name seems to be the important bit, implying a memory function, but the rest of the definition seems somewhat negotiable — enough so that you can make a memristor from a bit of photochromic dye.

Now, we’ll leave the discussion of whether [Markus Bindhammer]’s rather complex optical memory cell officially counts as a memristor to the comments below, and just go through the technical details here. The heart of this experimental device is a photochromic dye known as cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene, mercifully shortened to CMTE, which has the useful property of having two stable states. Transitioning from the open state to the closed state occurs when UV light shines upon it, while switching back to the closed state is accomplished with a pulse of green light. Absent the proper wavelength of light, both states are stable, making non-volatile information storage possible.

To accomplish this trick, [Markus] filled a quartz cuvette with a little CMTE-doped epoxy resin. Inside a light-tight enclosure, two lasers — one at 405 nm wavelength, the other at 532 nm — are trained on the cuvette through a dichroic mirror. On the other side of the CMTE resin, he placed a VEML7700 high-accuracy ambient light sensor. An Arduino Nano reads the light sensor and controls the lasers. Writing and erasing are accomplished by turning on the proper laser for a short amount of time; reading the state of the cell involves a carefully timed pulse from the 405 nm laser followed by a 532 nm pulse and watching the output of the sensor.

Is a one-bit memory device that uses a dye that goes for €300 per gram and a pair of laser diodes practical? Of course not, but it’s still pretty cool, and we appreciate all the effort and expense [Markus] went to with this one. Now, if you want some fuel for the “It’s not a memristor” fire, memristors might not even be a thing.

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Meet The Optical Data Format You’ve Never Heard Of Before

October 10, 2024 by Lewin Day 80 Comments

You consider yourself a power user. You’ve got lots of files, and damn it, you like to keep them backed up. Around a decade ago, you gave up on burning optical discs, and switched to storing your files on portable hard drives. One local, one off-site, and a cloud backup just to be sure. You’re diligent for a home gamer, and that gets you done.

The above paragraph could describe any number of Hackaday readers, but what of bigger operations? Universities, businesses, and research institutions all have data budgets far in excess of what the individual could even imagine. What might shock you is that some of them are relying on optical media—just not the kind you’ve ever heard of before. Enter Sony’s Optical Disc Archive.

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The Internet Archive Has Been Hacked

October 10, 2024 by Lewin Day 33 Comments

There are a great many organizations out there, all with their own intentions—some selfish, some selfless, some that land somewhere in between. Most would put the Internet Archive in the category of the library—with its aim of preserving and providing knowledge for the aid of all who might call on it. Sadly, as [theresnotime] reports, it appears this grand institution has been hacked.

On Wednesday, users visiting the Internet Archive were greeted with a foreboding popup that stated the following:

Have you ever felt like the Internet Archive runs on sticks and is constantly on the verge of suffering a catastrophic security breach? It just happened. See 31 million of you on HIBP!

The quote appears to refer to Have I Been Pwned (HIBP), a site that collates details of security breaches so individuals can check if their details have been compromised.

According to founder Brewster Kahle, the site was apparently DDOS’d, with the site defaced via a JavaScript library. It’s believed this may have been a polyfill supply chain attack. As for the meat of the hack, it appears the individuals involved made off with usernames, emails, and encrypted and salted passwords. Meanwhile, as Wired reports, it appears Have I Been Pwned first received the stolen data of 31 million users on September 30.

At the time of writing, it appears the Internet Archive has restored the website to some degree of normal operation. It’s sad to see one of the Internet’s most useful and humble institutions fall victim to a hack like this one. As is always the way, no connected machine is ever truly safe, no matter how much we might hope that’s not the case.

[Thanks to Sammy for the tip!]

Wimbledon Goes Automated

October 10, 2024 by Al Williams 4 Comments

When you think of tennis, you probably think of Wimbledon, the All England Club’s famous competition that has run for 147 years. Part of that history has always been line judges who call the ball in or out, sometimes to the ire of players and fans alike. But line judges will be no more at Wimbledon. They are moving to ELC or electronic line calling on all courts in both the main draw and the qualifying tournaments, according to [Tumaini Carayol] writing in The Guardian.

Of course, in 2007, the competition started using “Hawk-Eye,” which allows for review and challenges of the calls. ELC has also been used in other venues, such as the US Open, which has also done away with all line judges.

In fact, the only grand slam tournament that isn’t using ELC now is the French Open. There is some concern, however. The increased availability of line judges will cut down on the demand for new line judges at lesser tournaments. However, these jobs are a common pathway for aspiring chair judges to gain experience and exposure.

According to the Bloomberg video below, the system uses cameras and microphones to keep track of the ball’s position. Other reports say there are 18 cameras and, apparently, the system uses a computer-generated voice to call “out,” “fault,” or “foot fault.”

Apparently, there are some downsides, however. Last month at the US Open, play was halted because the remote office of the technicians operating the ELC system had to evacuate due to a fire alarm.

[Lewin Day] thinks tech will ruin sports. He may be right. Of course, we are more likely to play sports on technology.

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The Punched Card Detective

October 9, 2024 by Al Williams 31 Comments

[John Graham-Cumming] might not be the first person to thumb through an old book and find an IBM punched card inside. But he might be the first to actually track down the origin of the cards. Admittedly, there were clues. The book was a Portuguese book about computers from the 1970s. The cards also had a custom logo on them that belonged to a computer school at the time.

A Hackaday card, thanks to the online card punch

It is hard to remember, but there was a time when cards reigned supreme. Sometimes called Hollerith cards after Herman Hollerith, who introduced the cards to data processing, these cards used square holes to encode information. Reading a card is simple. There are 80 columns on a classic card. If a column has a single punch over a number, then that’s what that column represents. So if you had a card with a punch over the “1” followed by a punched out “5” in the next column and a “0” in the column after that, you were looking at 150. No punches, of course, was a space.

So, how did you get characters? The two blank regions above the numbers are the X and Y zones (or, sometimes, the 11 and 12 zones). The “0” row was also sometimes used as a zone punch. To interpret a column, you needed to know if you expected numbers or letters. An 11-punch with a digit indicated a negative number if you were expecting a number. But it could also mean a particular letter of the alphabet combined with one or more punches in the same column.

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