Ditto That

April 3, 2025 by Kristina Panos 23 Comments

In the 1982 movie Fast Times At Ridgemont High, a classroom of students receives a set of paperwork to pass backward. Nearly every student in the room takes a big whiff of their sheet before setting it down. If you know, you know, I guess, but if you don’t, keep reading.

Those often purple-inked papers were fresh from the ditto machine, or spirit duplicator. Legend has it that not only did they smell good when they were still wet, inhaling the volatile organic compounds within would make the sniffer just a little bit lightheaded. But the spirit duplicator didn’t use ghosts, it used either methanol (wood alcohol), isopropyl, or, if you were loaded, ethyl alcohol.

Invented in 1923 by Wilhelm Ritzerfeld, ditto machines were popular among schools, churches, and clubs for making copies of worksheets, fliers, and so on before the modern copy machine became widespread in the 1980s. Other early duplicating machines include the mimeograph, the hectograph, and the cyclostyle.

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Australia’s Steady March Towards Space

April 2, 2025 by Lewin Day 27 Comments

The list of countries to achieve their own successful orbital space launch is a short one, almost as small as the exclusive club of states that possess nuclear weapons. The Soviet Union was first off the rank in 1957, with the United States close behind in 1958, and a gaggle of other aerospace-adept states followed in the 1960s, 1970s, and 1980s. Italy, Iran, North Korea and South Korea have all joined the list since the dawn of the new millennium.

Absent from the list stands Australia. The proud island nation has never stood out as a player in the field of space exploration, despite offering ground station assistance to many missions from other nations over the years. However, the country has continued to inch its way to the top of the atmosphere, establishing its own space agency in 2018. Since then, development has continued apace, and the country’s first orbital launch appears to be just around the corner.

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The Everlasting Hunt For The Loch Ness Monster

April 1, 2025 by Jenny List 8 Comments

When a Loch Ness Monster story appears at the start of April, it pays to check the date on the article just to avoid red faces. But there should be no hoax with this one published on the last day of March, scientists from the UK’s National Oceanography Centre were conducting underwater robotics tests in Scotland’s Loch Ness, and stumbled upon a camera trap lost by Nessie-hunters in the 1970s. Just to put the cherry on the cake of a perfect news story, the submarine in question is the famous “Boaty McBoatface”, so named as a consolation after the British Antarctic Survey refused to apply the name to their new ship when it won an online competition.

The Most Extreme Instamatic in The World

An NOC scientist holds the camera in its container — Sadly the NOC haven’t released close-ups of the inner workings of the device.

The camera trap has survived five decades underwater thanks to a sturdy glass housing, and appears to be quite an ingenious device. A humble Kodak Instamatic camera with a 126 film and a flash bulb is triggered and has its film advanced by a clockwork mechanism, in turn operated by a bait line. Presumably because of the four flash bulbs in the Kodak’s flash cube, it’s reported that it could capture four images. The constant low temperature at the bottom of a very deep loch provided the perfect place to store exposed film, and they have even been able to recover some pictures. Sadly none of then contain a snap of Nessie posing for the camera.

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Zink Is Zero Ink — Sort Of

March 31, 2025 by Al Williams 36 Comments

When you think of printing on paper, you probably think of an ink jet or a laser printer. If you happen to think of a thermal printer, we bet you think of something like a receipt printer: fast and monochrome. But in the last few decades, there’s been a family of niche printers designed to print snapshots in color using thermal technology. Some of them are built into cameras and some are about the size of a chunky cell phone battery, but they all rely on a Polaroid-developed technology for doing high-definition color printing known as Zink — a portmanteau of zero ink.

For whatever reason, these printers aren’t a household name even though they’ve been around for a while. Yet, someone must be using them. You can buy printers and paper quite readily and relatively inexpensively. Recently, I saw an HP-branded Zink printer in action, and I wasn’t expecting much. But I was stunned at the picture quality. Sure, it can’t print a very large photo, but for little wallet-size snaps, it did a great job.

The Tech

Polaroid was well known for making photographic paper with color layers used in instant photography. In the 1990s, the company was looking for something new. The Zink paper was the result. The paper has three layers of amorphochromic dyes. Initially, the dye is colorless, but will take on a particular color based on temperature.

The key to understanding the process is that you can control the temperature that will trigger a color change. The top layer of the paper requires high heat to change. The printer uses a very short pulse, so that the top layer will turn yellow, but the heat won’t travel down past that top layer.

The middle layer — magenta — will change at a medium heat level. But to get that heat to the layer, the pulse has to be longer. The top layer, however, doesn’t care because it never gets to the temperature that will cause it to turn yellow.

The bottom layer is cyan. This dye is set to take the lowest temperature of all, but since the bottom heats up slowly, it takes an even longer pulse at the lower temperature. The top two layers, again, don’t matter since they won’t get hot enough to change. A researcher involved in the project likened the process to fried ice cream. You fry the coating at a high temperature for a short time to avoid melting the ice cream. Or you can wait, and the ice cream will melt without affecting the coating.

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Supercon 2024: Killing Mosquitoes With Freaking Drones, And Sonar

March 25, 2025 by Elliot Williams 50 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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High Frequency Food: Better Cutting With Ultrasonics

March 21, 2025 by Lewin Day 37 Comments

You’re cutting yourself a single slice of cake. You grab a butter knife out of the drawer, hack off a moist wedge, and munch away to your mouth’s delight. The next day, you’re cutting forty slices of cake for the whole office. You grab a large chef’s knife, warm it with hot water, and cube out the sheet cake without causing too much trauma to the icing. Next week, you’re starting at your cousin’s bakery. You’re supposed to cut a few thousand slices of cake, week in, week out. You suspect your haggardly knifework won’t do.

In the home kitchen, any old knife will do the job when it comes to slicing cakes, pies, and pastries. When it comes to commercial kitchens, though, presentation is everything and perfection is the bare minimum. Thankfully, there’s a better grade of cutting tool out there—and it’s more high tech than you might think.

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Checking In On The ISA Wars And Its Impact On CPU Architectures

March 18, 2025 by Maya Posch 33 Comments

An Instruction Set Architecture (ISA) defines the software interface through which for example a central processor unit (CPU) is controlled. Unlike early computer systems which didn’t define a standard ISA as such, over time the compatibility and portability benefits of having a standard ISA became obvious. But of course the best part about standards is that there are so many of them, and thus every CPU manufacturer came up with their own.

Throughout the 1980s and 1990s, the number of mainstream ISAs dropped sharply as the computer industry coalesced around a few major ones in each type of application. Intel’s x86 won out on desktop and smaller servers while ARM proclaimed victory in low-power and portable devices, and for Big Iron you always had IBM’s Power ISA. Since we last covered the ISA Wars in 2019, quite a lot of things have changed, including Apple shifting its desktop systems to ARM from x86 with Apple Silicon and finally MIPS experiencing an afterlife in the form of LoongArch.

Meanwhile, six years after the aforementioned ISA Wars article in which newcomer RISC-V was covered, this ISA seems to have not made the splash some had expected. This raises questions about what we can expect from RISC-V and other ISAs in the future, as well as how relevant having different ISAs is when it comes to aspects like CPU performance and their microarchitecture.

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