Decentralized Privacy-Preserving Proximity Tracing

April 9, 2020 by Jenny List 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 Jenny List 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.

Help Save The National Videogame Museum

April 6, 2020 by Jenny List 16 Comments

The National Videogame Museum in Sheffield, UK, houses a unique collection celebrating all decades of video games and their culture, and as the lockdown has brought with it a crisis threatening its very existence, has launched a crowdfunding campaign with a video we’ve placed below the break. As a relatively young organisation, they have yet to build up the financial buffer that a more established one would have. It’s important that this and other heritage sites live to open again another day, so we’d urge you to take a look.

On their website they’re providing a page of activities for the bored youngster in your life, but to whet your appetite should you wish to visit them in the future they also have a selection of pages about the rest of their exhibition.

One of the sad features of living through a pandemic comes in knowing that some of the businesses and organisations we hold dear might not make it through the crisis. We’ve put in a few orders to smaller suppliers over the last week or two to shove a bit of extra business their way, and no doubt you have too. What is not so easy however, is when the threatened organisation is a visitor attraction; we can’t make the trip during a lockdown. The NVM is unlikely to be the only such attraction facing the pinch, so we’d urge you to look out for those that are close to you as well.

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Download A Bit Of Sinclair History

April 6, 2020 by Jenny List 14 Comments

If you are a devotee of the Sinclair series of 8-bit home computers then a piece of news from the Centre For Computing History in Cambridge may be of interest to you, they’ve released a copy of the ROM from their ZX Spectrum prototype. This machine surfaced last year as part of a donation form the company originally contracted to write the Spectrum ROM and has been given pride of place int heir exhibition ever since. They’ve been doing some very careful work on it, and while The Register reports they can’t yet make the board boot, they have extracted the code for study. In the video below the break, we see it running on the Speccy emulator on an older Windows PC.

The ROM comes with an invitation to the ZX Spectrum community to analyze it against the stock version, in the hope of revealing ossified fragments of code such as that for the Microdrive storage peripheral which never made it into the stock Spectrum. But should you simply want to try your favorite games with the earliest possible version of the ROM, you can do that too.

We covered the machine’s emergence last year, meanwhile, if you haven’t been to the Centre for Computing History yet, we suggest you take a look at our review from a few years ago.

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Turn Off Those Batteries With Their Protection Chip

April 5, 2020 by Jenny List 24 Comments

It should be a feature of every device powered by a lithium-ion battery, that it has a protection chip on board that automatically disconnects it should it go out of its safe voltage range. A chip most often used for this purpose in single-cell applications is the Fortune Semiconductor DW01, and [Oliver] shares a tip for using this chip to power down the battery. The DW01 has a CS, or current sense pin, which if taken high momentarily will put the chip into an off state until the battery is disconnected.

Looking at the DW01 datasheet we can see that this would work, but we can’t help having a few questions. The CS pin is a safety sensor pin, providing over current, short circuit, and reverse polarity detection. It’s the kind of pin one might mess with only when one is absolutely certain it’s not likely to trigger a dangerous fault condition, so a bit of care should be required. However, we can see that leaving its resistor in place and supplying it a momentary logic level through another resistor should work. We’d be interested in the views of any readers with more experience in the world of lithium battery protection on this hack.

Meanwhile, a good read for any reader should be our look last year at lithium-ion safety.

Is This The Oldest Still-Working Geostationary Satellite?

April 4, 2020 by Jenny List 39 Comments

Regular followers of space news will know that when satellites or space probes reach the end of their life, they either are de-orbited in a fiery re-entry, or they stay lifeless in orbit, often in a safe graveyard orbit where they are unlikely to harm other craft. Sometimes these deactivated satellites spring back into life, and there is a dedicated band of enthusiasts who seek out these oddities. Dead satellite finder extraordinaire [Scott Tilley] has turned up a particularly unusual one, a craft that is quite likely to be the oldest still-working geostationary satellite.

LES-5 is an experimental satellite built by MIT’s Lincoln Labs, launched in 1967, and used to test military UHF communications in a geosynchronous orbit. It had an active life into the early 1970s after which it was placed in a graveyard orbital slot for redundant craft. It’s lain forgotten ever since, until this month when [Scott] found its beacon transmitting on 236.75 MHz. The Twitter thread is an extremely interesting glimpse into the satellite finder’s art, as first he’s not certain at all that it is LES-5 so he waits for its solar eclipse to identify its exact position.

Whether anything on the craft can find another use today is not certain, as he finds no evidence of its transponder. Still, that something is working again 53 years after its launch is a testament to the quality of its construction. Should its transponder be reactivated again it’s not impossible that people might find illicit uses for it, after all that’s not the first time this has happened.

Full-Colour, Full-Motion Video – On An Audio Cassette!

April 3, 2020 by Jenny List 29 Comments

A lot of projects we feature use video in some form or other, but that video is invariably digital, it exists as a stream of numbers in a computer memory or storage, and is often compressed. For some of us who grew up working with composite video there is a slight regret that we rarely get up-close and personal with an analogue stream, so [Kris Slyka]’s project putting video on a conventional audio cassette is a rare opportunity.

It's fair to say this isn't the highest quality video. — It’s fair to say this isn’t the highest quality video.

Readers with long memories may recall the Fisher-Price PixelVision toy from the late 1980s which recorded black-and-white video on a conventional cassette running at many times normal speed. This system does not take that tack, instead it decreases resolution and frame rate to a point at which it can be recorded at conventional cassette speeds. The result is not particularly high quality, but with luminance on one side of a stereo recording and chrominance on the other it does work.

The video below the break is a run through the system, with an explanation of how video signals work. Meanwhile the code for both encoder and decoder are available through the magic of GitHub. If you’re interested further, take a look at our examination of a video waveform.

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