Vulkan For The Older Raspberry Pi

June 22, 2020 by Jenny List 7 Comments

You’d be forgiven for thinking that the newer Raspberry Pi 4 gets all the love. For instance, the Raspberry Pi Foundation is working on drivers for the GPU to support the Vulkan 3D graphics API.

But those of you with crusty old Pi boards shouldn’t despair. [Martin Thomas], a developer working for Nvidia has produced a driver in his spare time that brings Vulkan to the Broadcom VideoCore IV. He’s hailed it as the first low-level driver for this GPU, and shown it running Quake III on a Pi 3.

Technically it’s not officially Vulkan as it doesn’t have all the required standards conformance, but it’s as near as possible given the limitations of the hardware. Full instructions for building the driver and for installing the Vulkan loader are given in the repository, so it should be possible for tinkerers to have a try. This is likely to be of most interest to gamers as many game engines support Vulkan.

The Pi 4 might be about to take the family further in a 64-bit direction, but this proves that there’s life in the old dogs yet.

Just How Do Aircraft Transponders Work Anyway?

June 22, 2020 by Jenny List 32 Comments

Most of us will have a hazy idea of how radar works to detect aircraft by listening for reflected radio waves. And we’ll probably also know that while radar can detect aircraft, it’s not the most efficient or useful tool in the hands of an air traffic controller. Aircraft carry transponders so that those on the ground can have a clearer picture of the skies, as each one reports its identity, altitude, and position. [Yeo Kheng Meng] was lucky enough to secure a non-functioning aircraft transponder and do a teardown, and his write-up makes for interesting reading as he explains their operation before diving into the hardware.

The 1978 and 1979 date codes on the various integrated circuits and transistors identify it as having been made in 1979, so not having a CPU is not entirely unsurprising given its age. Instead this is a straightforward device that responds to pulse lengths of different timings with sequential bursts of data.

[Yeo Kheng] is mystified by the RF strip and associated components, which look to us like a typical crystal oscillator and frequency multiplier strip from that era, along with some screened boxes that probably contain cavity filters and given that there is also a high voltage power supply present, a tube RF power amplifier. GHz-capable semiconductors were quite exotic in the 1970s, while high-frequency tubes had by then a long history.

It’s evident that the tech behind aircraft transponders has moved on since this unit was built, but one thing’s certain. Hackers in 1978 would have had to go to a lot of work to listen to them and interpret the results, while here in the 21st century it’s something we do routinely.

Help Thrust Open Source Satellites To The Next Level

June 21, 2020 by Jenny List 12 Comments

To place a satellite in orbit satisfactorily it is necessary not only to hitch a ride on a rocket, but also to put it in the right orbit for its task, and once it is there, to keep it there. With billions of dollars or roubles of investment over six decades of engineering behind them the national space agencies and commercial satellite builders solved these problems long since, but replicating those successes for open source microsatellites still represents a significant engineering challenge. One person working in this field is [Michael Bretti], who is doing sterling work with a shoestring budget on open source electric thrusters for the smallest of satellites, and he needs your help in crowdfunding a piece of equipment.

Beware suspiciously cheap eBay vacuum pumps!

As part of his testing he has a vacuum chamber, and when he places a thruster inside it he has to create a space-grade vacuum . This is no easy task, and to achieve it he has two pumps. The first of these, a roughing pump, is a clapped-out example that has clearly reached the end of its days, and it is this that he needs your help to replace. His GoFundMe page has a modest target of only $4,200 which should be well within the capabilities of our community in reaching, and in supporting it you will help the much wider small satellite community produce craft that will keep giving us interesting things from space for years to come.

We’ve mentioned his work before here at Hackaday, and we hope that in time we’ll have a chance to look in more detail at his thrusters. Meanwhile you can follow along on Twitter.

Thanks [Bruce Perens K6BP] for the tip.

Chasing A Long-Obsolete Tube

June 20, 2020 by Jenny List 12 Comments

Regular readers will know that here at Hackaday we have a penchant for poking fun at the more silly end of the audiophile world, with its dubious accessories and purple prose. It’s worth remembering though that this is not representative of the whole discipline of audio design, indeed the quest for perfect audio reproduction contains plenty of complex engineering problems.

We’re indebted to [macsimski] then for sending us a link to a page from Phaedrus Audio from a year or two ago, in which they discuss the history of an unusual pentode tube used as an impedance converter in a series of legendary post-war microphones. It’s unlikely that you’ll have a Neumann U47 or U48 broadcast microphone on your bench, but even so the story behind their design is one that should fascinate anyone.

It takes us back to the period immediately following the Second World War, when German electricity supplies were varied and unreliable, and radio receivers designed for them required new tubes from the manufacturers. Among these was the VF14, with an unusual high-voltage heater designed such that two of them could be connected in series across the supply. This and its compact shape prompted its selection for the professional microphones, even though its performance was so poor that only a third of the production passed the performance test.

Since it passed out of production in the early 1950s the remaining components are extremely rare, and the majority of those surviving do not meet the performance characteristics of the microphone. The Phaedrus write-up goes into significant technical detail which should be of note to anyone with an interest in tubes, and ends up with their reason for it all, a plug-in hardware simulation of the original tube’s properties. Vintage capacitor microphones may be out of the ordinary for Hackaday, but it’s still a good read.

For a bit more on capacitor microphones it’s worth a look at our dive into electrets.

Header image: JacoTen / CC BY-SA 3.0

Key That Morse With Little More Than Your Laptop

June 20, 2020 by Jenny List 20 Comments

If you look at the computer in front of you, it will have an array of input devices. A keyboard and mouse, a touch screen, maybe a microphone, or even a gamepad. Each of them will have its moment to shine, and you’ll probably have put some effort into their selection. But when it comes to a computer, almost anything connected to it can be an input device in some form, as long as it provides some form of machine readable parameter.

Consider your laptop: it knows when its lid is closed such that it can put itself to sleep. Even that can be used as an input device with a little ingenuity, as [veggiedefender] has done with “open and shut“, a Morse keyer using opening and closing the laptop lid as its key.

The software for GNU/Linux distributions is a surprisingly accessible set of shell scripts that attach themselves to ACPI events surrounding the lid switch. In use it seems a little cumbersome, but we suspect its real value is not in repeatedly slammin the lid to produce Morse text input. Instead with many lid switches being magnetic reed switches an operator could simply wear a ring with a magnet and tap out their text every bit as quickly as they could using a traditional key.

We like the idea, and could see it being popular among radio amateurs. It’s a theme we’ve visited before with a more traditional key, and if you’d love to try but don’t know any Morse then perhaps this may help you learn.

Thanks [Kickaxe] for the tip.

Header image: Raimond Spekking / CC BY-SA 4.0.

Justice For The Gatwick Two: The Final Chapter In The British Drone Panic Saga

June 17, 2020 by Jenny List 27 Comments

At the end of 2018, a spate of drone sightings caused the temporary closure of London Gatwick Airport, and set in train a chain of events that were simultaneously baffling and comedic as the authorities struggled to keep up with both events and the ever widening gap in their knowledge of the subject.

One of the more inept actions of the Sussex Police was to respond by arresting the first local drone enthusiast they could find on Facebook, locking up a local couple for 36 hours and creating a media frenzy by announcing the apprehension of the villains before shamefacedly releasing them without charge.

In a final twist to the sorry saga, the couple have sued the force for wrongful arrest and false imprisonment, for which the cops have had to make a £200,000 ($250,117) payout including legal fees.

We reported extensively on the events surrounding the case 18 months ago, and then on a follow-up event at London Heathrow airport. The mass media at the time were full of the official line that drone hobbyists must be at fault, but then as now we were more interested in seeing some hard evidence. As we said then: Show us the drone.

So how has the new drone law progressed, since it was decided that Something Must Be Done? Enthusiasts have continued as before, and the multirotor community is as technically creative as ever. We were fortunate enough to host the Lets Drone Out podcast at MK Makerspace back in those halcyon days before the pandemic and see the state of the art in sub-250g craft, and with those and commercial offerings such as the DJI Mavic Mini all requiring no registration there is increasingly little need for an enthusiast to purchase a larger machine. The boost to the British drone industry we were promised has instead been a boost for the Chinese industry as we predicted, and of course we’re still waiting for the public inquiry into the whole mess. Something tells us Hell will freeze over first.

If you’d like the whole backstory in a convenient and entertaining video format, can we direct you to this talk at CCCamp 2019.

Thanks [Stuart Rogers] for the tip.

Keystone Kops header image: Mack Sennett Studios [Public domain].

Surviving The Pandemic As A Hacker: Take Care Of Your Mental Health

June 17, 2020 by Jenny List 42 Comments

As we’ve looked at the subject of face masks in the first two parts of this series, our emphasis has been on a physical step to aid your chances of making it through the COVID-19 pandemic in one piece. But given that the upheaval caused by all the social changes enacted to protect the population are likely to leave an indelible mark on those who live through them, there are significant aspects of surviving all this that go beyond the physical.

This will be a once-in-a-lifetime event for many people, a significant number will find it traumatic in some way, and for many of those people there will be an immediate and then ongoing effect on mental health. If anyone is in doubt as to from what position this is coming, I count myself among that number.

The Pressure Of A Once In A Lifetime Event

Piccadilly Circus, London, during the COVID-19 lockdown. Normally this is packed. Kwh1050 / CC BY-SA 4.0

Different countries have placed their own public health restrictions on their populations, but it’s likely that many of you are in some form of lockdown situation, with social or communal activities and locations closed or curtailed, going out restricted, and with all around you in the same situation. A perfect storm of having social outlets removed while simultaneously being stuck at home perhaps with family or housemates you’d prefer not to spend too much time with is not ideal. Add to that the multiple stresses from the pandemic itself as well as other news stories from our turbulent world, and it’s hardly a surprising that it’s taking a toll. Continue reading “Surviving The Pandemic As A Hacker: Take Care Of Your Mental Health” →