Supercon 2024: Killing Mosquitoes With Freaking Drones, And Sonar

March 25, 2025 by 52 Comments

Suppose that you want to get rid of a whole lot of mosquitoes with a quadcopter drone by chopping them up in the rotor blades. If you had really good eyesight and pretty amazing piloting skills, you could maybe fly the drone yourself, but honestly this looks like it should be automated. [Alex Toussaint] took us on a tour of how far he has gotten toward that goal in his amazingly broad-ranging 2024 Superconference talk. (Embedded below.)

The end result is an amazing 380-element phased sonar array that allows him to detect the location of mosquitoes in mid-air, identifying them by their particular micro-doppler return signature. It’s an amazing gadget called LeSonar2, that he has open-sourced, and that doubtless has many other applications at the tweak of an algorithm.

Rolling back in time a little bit, the talk starts off with [Alex]’s thoughts about self-guiding drones in general. For obstacle avoidance, you might think of using a camera, but they can be heavy and require a lot of expensive computation. [Alex] favored ultrasonic range finding. But then an array of ultrasonic range finders could locate smaller objects and more precisely than the single ranger that you probably have in mind. This got [Alex] into beamforming and he built an early prototype, which we’ve actually covered in the past. If you’re into this sort of thing, the talk contains a very nice description of the necessary DSP.

[Alex]’s big breakthrough, though, came with shrinking down the ultrasonic receivers. The angular resolution that you can resolve with a beam-forming array is limited by the distance between the microphone elements, and traditional ultrasonic devices like we use in cars are kinda bulky. So here comes a hack: the TDK T3902 MEMS microphones work just fine up into the ultrasound range, even though they’re designed for human hearing. Combining 380 of these in a very tightly packed array, and pushing all of their parallel data into an FPGA for computation, lead to the LeSonar2. Bigger transducers put out ultrasound pulses, the FPGA does some very intense filtering and combining of the output of each microphone, and the resulting 3D range data is sent out over USB.

After a marvelous demo of the device, we get to the end-game application: finding and identifying mosquitoes in mid-air. If you don’t want to kill flies, wasps, bees, or other useful pollinators while eradicating the tiny little bloodsuckers that are the drone’s target, you need to be able to not only locate bugs, but discriminate mosquitoes from the others.

For this, he uses the micro-doppler signatures that the different wing beats of the various insects put out. Wasps have a very wide-band doppler echo – their relatively long and thin wings are moving slower at the roots than at the tips. Flies, on the other hand, have stubbier wings, and emit a tighter echo signal. The mosquito signal is even tighter.

If you told us that you could use sonar to detect mosquitoes at a distance of a few meters, much less locate them and differentiate them from their other insect brethren, we would have thought that it was impossible. But [Alex] and his team are building these devices, and you can even build one yourself if you want. So watch the talk, learn about phased arrays, and start daydreaming about what you would use something like this for.

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Repairing A Kodak Picture Maker Kiosk

March 15, 2025 by 9 Comments

Photo-printing kiosks are about as common as payphones these days. However, there was a time when they were everywhere. The idea was that if you didn’t have a good printer at home, you could take your digital files to a kiosk, pay your money, and run off some high-quality images. [Snappiness] snagged one, and if you’ve ever wondered what was inside of one, here’s your chance.

While later models used a Windows PC inside, this one is old enough to have a Sun computer. That also means that it had things like PCMCIA slots and a film scanner. Unfortunately, it wasn’t working because of a bad touch screen. The box was looking for a network on boot, which required some parameter changes. The onboard battery is dead, too, so you have to change the parameters on every boot. However, the real killer was the touchscreen, which the software insists on finding before it will start.

The monitor is an old device branded as a Kodak monitor and, of course, is unavailable. [Snappiness] found pictures of another kiosk online and noted that the monitor was from Elo, a common provider of point-of-sale screens. Could the “Kodak” monitor just be an Elo with a new badge? It turns out it probably was because a new Elo monitor did the trick.

Of course, what excited us was that if we found one of these in a scrap pile, it might have a Sun workstation inside. Of course, you can just boot Solaris on your virtual PC today. You might be surprised that Kodak invented the digital camera. But they failed to understand what it would mean to the future of photography.

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Tiny Laptop Gets A New Case And An Unlocking

March 11, 2025 by 25 Comments

Unless you’ve got an especially small lap, calling the Toshiba Libretto a laptop is a bit of a stretch. The diminutive computers from the mid-1990s had a lot of the usual laptop features, but in an especially compact and portable case that made them a great choice for anyone with an on-the-go lifestyle.

Fast-forward thirty years or so, and the remaining Librettos haven’t fared too well. Many of them have cases that crumble at the slightest touch, which is what led [polymatt] to undertake this meticulous case replacement. The effort started with a complete teardown; luckily, the lower aluminum-alloy shell was in fine shape, but the upper case parts were found to be almost too deteriorated to handle. Still, with a little patience and the judicious application of tape, [polymatt] was able to scan the case pieces on a flatbed scanner and import them into his CAD package. Great tip on the blue-tack for leveling the parts for accurate scanning, by the way.

After multiple rounds of printing and tweaking, [polymatt] had a case good enough to reassemble the Libretto. Unfortunately, the previous owner left an unwanted gift: a BIOS password. Disconnecting the CMOS battery didn’t reset it, but a little research told him that shorting a few pins on the parallel port on the machine’s dock should do the trick. It was a bit involved, requiring the design and subsequent bodging of a PCB to fit into the docking port connector, but in the end he was able to wake up a machine to all its Windows 95 glory. Better get patching.

In a time when laptops were more like lap-crushers, the Libretto was an amazing little machine, and thirty years on, they’re well worth saving from the scrap heap. Hats off to [polymatt] for the effort to save this beauty, and if he needs tips on reading data from any PCMCIA cards that may have come with it, we’ve got him covered.

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Reconstructing 3D Objects With A Tiny Distance Sensor

February 20, 2025 by 7 Comments

There are a whole bunch of different ways to create 3D scans of objects these days. Researchers at the [UW Graphics Lab] have demonstrated how to use a small, cheap time-of-flight sensor to generate scans effectively.

Not yet perfect, but the technique does work…

The key is in how time-of-flight sensors work. They shoot out a distinct pulse of light, and then determine how long that pulse takes to bounce back. This allows them to perform a simple ranging calculation to determine how far they are from a surface or object.

However, in truth, these sensors aren’t measuring distance to a single point. They’re measuring the intensity of the received return pulse over time, called the “transient histogram”, and then processing it. If you use the full mathematical information in the histogram, rather than just the range figures, it’s possible to recreate 3D geometry as seen by the sensor, through the use of some neat mathematics and a neural network. It’s all explained in great detail in the research paper.

The technique isn’t perfect; there are some inconsistencies with what it captures and the true geometry of the objects its looking at. Still, the technique is young, and more work could refine its outputs further.

If you don’t mind getting messy, there are other neat scanning techniques out there—like using a camera and some milk.

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No Ham License? Listen Anyway In Your Browser

January 15, 2025 by 53 Comments

Full disclosure: ham radio isn’t for everyone, and there are many different facets to it. What appeals to one person might bore another to death. One area of ham radio that has changed a lot in the last few years is more or less local and typically mobile operation on VHF or UHF. Not long ago, hams used HTs (walky-talkies or handi-talkies) or mobile radios via repeaters to talk to each other and — the golden prize back then — make phone calls from their cars. Cell phones have made that much less interesting, but there is still an active community of operators talking on repeaters. However, the traffic has gone digital, the Internet is involved, and people with inexpensive, low-powered radios can talk to each other across the globe. This is nothing new, of course. However, having digital services means that operators with special interests can congregate in what amounts to radio chat rooms organized by region or topic.

There’s a long history of people listening to ham radio conversations with shortwave radios, SDRs, and scanners. But with so much activity now carried on the Internet, you can listen in using nothing more than your web browser or a phone app. I’ll show you how. If you get interested enough, it is easy enough to get your license. You don’t need any Morse code anymore, and a simple Technician class license in the United States is all you need to get going.

A Quick DMR Primer

There are several digital ham networks around and like real networks, you can have different physical transport layers and then build on top of that. For the purposes of this post, I’m going to focus on DMR (digital mobile radio) on the Brandmeister network which is very large and popular ham network. You won’t need a license nor will you need to sign up for anything as long as you are content to just listen.

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Watch A 3D Scan Become A Car Body Model

December 20, 2024 by 1 Comment

Not all 3D scanning is alike, and the right workflow can depend on the object involved. [Ding Dong Drift] demonstrates this in his 3D scan of a project car. His goal is to design custom attachments, and designing parts gets a lot easier with an accurate 3D model of the surface you want to stick them on. But it’s not as simple as just scanning the whole vehicle. His advice? Don’t try to use or edit the 3D scan directly as a model. Use it as a reference instead.

Rather than manipulate the 3D scan directly, a better approach is sometimes to use it as a modeling reference to fine-tune dimensions.

To do this, [Ding Dong Drift] scans the car’s back end and uses it as a reference for further CAD work. The 3D scan is essentially a big point cloud and the resulting model has a very high number of polygons. While it is dimensionally accurate, it’s also fragmented (the scanner only captures what it can see, after all) and not easy to work with in terms of part design.

In [Ding Dong Drift]’s case, he already has a 3D model of this particular car. He uses the 3D scan to fine-tune the model so that he can ensure it matches his actual car where it counts. That way, he’s confident that any parts he designs will fit perfectly.

3D scanning has a lot of value when parts have to fit other parts closely and there isn’t a flat surface or a right angle to be found. We saw how useful it was when photogrammetry was used to scan the interior of a van to help convert it to an off-grid camper. Things have gotten better since then, and handheld scanners that make dimensionally accurate scans are even more useful.

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Man Overboard Systems Aim To Increase Survival Rates At Sea

December 17, 2024 by 22 Comments

When you hear the cry of “Man Overboard!” on a ship, it’s an emergency situation. The sea is unkind to those that fall from their vessel, and survival is never guaranteed—even in the most favorable conditions. Raging swell and the dark of night can only make rescue more impossible.

Over the centuries, naval tradition has included techniques to find and recover the person in the water as quickly and safely as possible. These days, though, technology is playing an ever-greater role in such circumstances. Modern man-overboard (MOB) systems are designed to give crews of modern vessels a fighting chance when rescuing those in peril.

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