Decentralized Privacy-Preserving Proximity Tracing

April 9, 2020 by 6 Comments

As we continue through the pandemic, whether we are on lockdown or still at work, there is a chance for all of us that we could still pick up the virus from a stray contact. Mapping these infections and tracing those in proximity to patients can present a major problem to infection control authorities, and there have been a variety of proposals for smartphone apps designed to track users’ contacts via the Bluetooth identities their phones encounter. This is a particular concern to privacy advocates, because there is a chance that some governments could use this as an excuse to bring in intrusive personal surveillance by this means. A group of academics from institutions across Europe have come together with a proposal for a decentralised proximity tracing system that allows identification of infection risk without compromising the privacy of those using it.

Where a privacy-intrusive system might use a back-end database tracking all users and recording their locations and interactions, this one uses anonymised tokens stored at the local level rather than at the central server. When a user is infected this is entered at app level rather than at server level, and the centralised part of the system merely distributes the anonymised tokens to the clients. The computation of whether contact has been made with an infected person is thus made on the client, meaning that the operator has no opportunity to collect surveillance data. After the pandemic has passed the system will evaporate as people stop using it, rather than remaining in place harvesting details from installed apps. They are certainly not the first academics to wrestle with this thorny issue, but they seem to have ventured further into the mechanics of it all.

As with all new systems, it’s probably good to subject it to significant scrutiny before deploying it live. Have a read. What do you think?

We are all watching our authorities as they race to respond to the pandemic in an effective manner, and we hope that should they opt for an app that it does an effective job and they resist the temptation to make it too intrusive. Our best course of action meanwhile as the general public is to fully observe all advised public health measures such as self-isolation or the wearing of appropriate personal protective equipment.

Adding RGB To A CRT

April 9, 2020 by 30 Comments

There was a time when all TVs came with only an antenna socket on their backs, and bringing any form of video input to them meant dicing with live-chassis power supplies. Then sets with switch-mode supplies made delving into a CRT TV much safer, and we could bodge in composite video and even RGB sockets by tapping into their circuitry. For Europeans the arrival of the SCART socket gave us ready-made connectivity, but in the rest of the world there was still a need to break out the soldering iron for an RGB input. [Jacques Gagnon] is in Canada, and has treated us to a bit of old-school TV input hacking as he put an RGB socket on his JVC CRT set.

Earlier hacks had inventive incursions into discrete analogue circuitry, but on later sets such as this one the trick was to take advantage of the on-screen-display features. The signal processing chip would usually have an RGB input with a blanking input to turn of the picture during the OSD chip’s output. These could be readily hijacked to provide an RGB input, and this is the course taken here. We see a VGA socket on the rear panel going to a resistor network on a piece of protoboard stuck in a vacant space on the PCB, from which a set of lines then go to the signal processing chip. The result is a CRT gaming monitor for retro consoles, of the highest quality.

For those of us who cut our teeth on CRT TVs it’s always good to see a bit of TV hacking. It’s a mod we’ve seen before, too.

Warm Up To Cooking With A Recipe-Randomizing Toaster

April 8, 2020 by 10 Comments

Did you get a thermal printer when they were hot stuff, but then your interest cooled when you couldn’t decide what to do with it? Something similar happened to [Sunyecz22], and the poor printer sat unused until that magical day when the perfect use for it popped up — a random recipe receiver in the form of a toaster.

[Sunyecz22] was tired of searching for recipes every week before going to the grocery store. Between the millions of recipe options on the internet and the 1000-word essays that precede them all, the process was like a part-time job. Now all they have to do is push the little lever down and wait for a recipe to get toasted into some thermal paper. It doesn’t print the full recipe, only the essentials, and we love that. You get the name, the prep time, a rating, and a QR code that links to the recipe page.

This toaster runs on a Raspberry Pi Zero W that fetches recipes using the Spoonacular API and sends the deets to the printer. The lever makes use of some old pen springs to activate a limit switch and start the recipe-getting process. We think it would be extra cool if it stayed down until the recipe popped up. Butter your way past the break to see a short demo video.

We must say, this toaster is way more helpful than the talkie toaster from Red Dwarf.

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The Libre Space Foundation Reviews Software Defined Radios

April 8, 2020 by 7 Comments

If you want to go to the next level with software defined radio (SDR), there are a lot of choices. The RTL-SDR dongles are fine, but if you get serious you’ll probably want something else. How do you choose? Well, your friends at the European Space Agency Libre Space Foundation have published a paper comparing many common options. True, they are mostly looking at how the receivers work with CubeSats, but it is still a good comparison.

The devices they examine are:

  • RTS-SDR v3
  • Airspy Mini
  • SDRPlay RSPduo
  • LimeSDR Mini
  • BladeRF 2.0 Micro
  • Ettus USRP B210
  • Pluto SDR

They looked at several bands of interest, but not the HF bands — not surprising considering that some of the devices can’t even operate on HF. They did examine VHF, UHF, L band, S band, and C band performance. Some of the SDRs have transmit capabilities, and for those devices, they tested the transmit function as well as receive.

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Teardown Of Oddball Night Vision Shows Off Retro-futuristic Vibe

April 8, 2020 by 14 Comments

Night vision aficionado [Nicholas C] shared an interesting teardown of a Norwegian SIMRAD GN1 night vision device, and posted plenty of pictures, along with all kinds of background information about their construction, use, and mounting. [Nicholas] had been looking for a night vision device of this design for some time, and his delight in finding one is matched only by the number of pictures and detail he goes into when opening it up.

The GN1 rocks an irresistible retro-futuristic look.

What makes the SIMRAD GN1 an oddball is the fact that it doesn’t look very much like other, better known American night vision devices. Those tend to have more in common with binoculars than with the GN1’s “handheld camera” form factor. The GN1 has two eyepieces in the back and a single objective lens on the front, which is off-center and high up. The result is a seriously retrofuturistic look, which [Nicholas] can’t help but play to when showing off some photos.

[Nicholas] talks a lot about the build and tears it completely down to show off the internal optical layout necessary to pipe incoming light through the image intensifier and bend it around to both eyes. As is typical for military hardware like this, it has rugged design and every part has its function. (A tip: [Nicholas] sometimes refers to “blems”. A blem is short for blemish and refers to minor spots on optics that lead to visual imperfections without affecting function. Blemished optics and intensifier tubes are cheaper to obtain and more common on the secondary market.)

In wrapping up, [Nicholas] talks a bit about how a device like this is compatible with using sights on a firearm. In short, it’s difficult at best because there’s a clunky thing in between one’s eyeballs and the firearm’s sights, but it’s made somewhat easier by the fact that the GN1 can be mounted upside down without affecting how it works.

Night vision in general is pretty cool stuff and of course DIY projects abound, like the OpenScope project which leverages digital cameras and 3D printing, as well as doing it the high-voltage image intensifier tube way.

Impressive Lever-Press Espresso Machine Has Finesse

April 8, 2020 by 8 Comments

Some people will do anything for a good cup of coffee, and we don’t blame them one bit — we’ve been known to pack up all our brewing equipment for road trips to avoid being stuck with whatever is waiting in the hotel room.

While this stylish lever-based industrial coffee machine made by [exthemius] doesn’t exactly make textbook espresso, it’s pretty darn close. Think of it like an Aeropress on steroids, or more appropriately, bulletproof coffee. As you can see in the demo after the break, the resulting coffee-spresso hybrid brew looks quite tasty.

Here’s how it works: finely-ground beans go in a pressurized portafilter basket that was scavenged from an entry-level prosumer espresso machine. Pour boiling water into the top of the cylinder, and pull the giant lever down slowly to force it through the portafilter. Presto, you’re in thin, brown flavor town.

We love the piston-esque plunger that [exthemius] made by layering washers and rubber gaskets up like a tiramisu. Although there are no plans laid out, there’s probably enough info in the reddit thread to recreate it.

If you ever do find yourself stuck with hotel house brand, soak it overnight to make it much more palatable.

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From The MacGyver Files: Using A Stepper Motor As An Encoder

April 8, 2020 by 27 Comments

It isn’t hard to imagine a scenario where you are stuck at home all day with nothing to do and certain items are in short supply. Sure, bathroom tissue gets all the press, but try buying some flour or a freezer and see how far you get. Plus online shopping has given up on next day delivery for the duration. Not hard to imagine at all. Now suppose your latest self-quarantine project needs a rotary shaft encoder. Not having one, what do you do? If you are [Tech Build] you go all MacGyver on an old printer and pull out a stepper motor.

How does a stepper motor turn into an encoder? Well, that’s the MacGyver part. We are not big fans of the physical circuit diagrams, but it looks like [Tech Build] borrowed (with credit) from an earlier post and that one has a proper schematic.

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