The Pi Pico, An SDR Receiver Front End

June 5, 2024 by Jenny List 22 Comments

Making a software defined radio (SDR) receiver is a relatively straightforward process, given the right radio front end electronics and analogue-to-digital converters. Two separate data streams are generated using clocks at a 90 degree phase shift, and these are passed to the software signal processing for demodulation. But what happens if you lack a pair of radio front ends and a suitable clock generator? Along comes [Mordae] with an SDR using only the hardware on a Raspberry Pi Pico. The result is a fascinating piece of lateral thinking, extracting something from the hardware that it was never designed to do.

The onboard RP2040 ADC is of course far too slow for the task, so instead an input is used, with a negative feedback arrangement from another GPIO to form a crude 1-bit ADC. A PIO peripheral is then used to perform the quadrature mixing, resulting in the requisite pair of data streams. At this point these are sent over USB to GNU Radio for demodulating, mainly for convenience rather than necessarily because the microcontroller lacks the power.

The result is a working SDR front end, demonstrated pulling in an FM broadcast station. The Pico has to be overclocked to reach that frequency and it’s more than a little noisy, but we’re extremely impressed with how much has been done with so little. Oddly it isn’t the first Pico SDR we’ve seen, but the previous one was a much more conventional and lower-frequency affair for the European Long Wave band.

The Amiga We All Wanted In 1993

June 4, 2024 by Jenny List 51 Comments

To be an Amiga fan during the dying days of the hardware platform back in the mid 1990s was to have a bleak existence indeed. Commodore had squandered what was to us the best computer ever with dismal marketing and a series of machines that were essentially just repackaged versions of the original. Where was a PCI Amiga with fast processors, we cried!

Now, thirty years too late, here’s [Jason Neus] with just the machine we wanted, in the shape of an ATX form factor Amiga motherboard with those all-important PCI slots and USB for keyboard and mouse.

What would have been unthinkable in the ’90s comes courtesy of an original or ECS Amiga chipset for the Amiga functions, and an FPGA and microcontroller for PCI and USB respectively. Meanwhile there’s also a PC floppy drive controller, based on work from [Ian Steadman]. The processor and RAM lives on a daughter card, and both 68040 and 68060 processors are supported.

Here in 2024 of course this is still a 1990s spec board, and misty-eyed speculation about what might have happened aside, it’s unlikely to become your daily driver. But that may not be the point, instead we should evaluate it for what it is. Implementing a PCI bus, even a 1990s one, is not without its challenges, and we’re impressed with the achievement.

If you’re interested in Amiga post-mortems, here’s a slightly different take.

Pasteurisation: Probably Why You Survived Childhood

June 4, 2024 by Jenny List 124 Comments

There’s an oft-quoted maxim that youngsters growing up on farms have a much stronger immune system than those growing up in cities. The idea is that they are exposed to far more dirt and eat food much closer to the field than their urban cousins. Without the help of a handy microbiologist or epidemiologist it’s difficult to judge its veracity, but personal experience suggests that the bit about dirt may be true at least.

It’s Dangerous To Idealise The Past.

It’s likely that the idea of rural kids seeing more bugs may come from the idea that those in the cities consume sterile processed food from the supermarket, it plays into a notion of an idealised past in which a somehow purer diet came more directly from its source. Somehow so the story goes, by only eating pasteurised and preserved foods, city dwellers are eating something inferior, stripped of its goodness. There’s a yearning for a purer alternative, something supermarkets are only too happy to address by offering premium products at elevated prices. So, was the diet of the past somehow more wholesome, and are those kids having their future health ruined by Big Food? Perhaps it’s time to turn back the clock a little to find out.

A mostly black cow in a field of green grass — Even clean cows have bugs. Carolyn Parsons, CC BY-SA 4.0.

It’s likely everyone knows that food spoils if left unattended for long enough. Some foods, such as grain, can last a long time if kept dry, while others such as milk will go bad quite quickly. Milk in particular goes bad for two reasons; firstly because it’s an excellent bacterial growth medium, and secondly because it contains plenty of bacteria by its very nature. Even very clean cows have bugs.

If you lived in most large cities in the nineteenth century, the Industrial Revolution had likely placed you far enough from the nearest cow that your milk had a significant journey to make to reach you even with up-to-date rail transport. Without refrigeration, during that journey it had become a bacterial soup to the extent that even though it might not yet have gone sour, it had certainly become a bacterial brew. It was thus responsible for significant numbers of infections, and had become a major health hazard. So much for the purer diet consumed by city kids of the past. Continue reading “Pasteurisation: Probably Why You Survived Childhood” →

A Human-Sized Strowger Telephone Exchange

June 3, 2024 by Jenny List 3 Comments

A large hacker camp such as EMF 2024 always brings unexpected delights, and one of those could be found in the Null Sector cyberpunk zone: a fully functional Strowger mechanical telephone exchange. Better still, this wasn’t the huge array of racks we’ve come to expect from a mechanical exchange, but a single human-sized unit, maybe on a similar scale to a large refrigerator. [LBPK]’s PAX, or Private Automatic Exchange, is a private telephone network, 1950s style.

It stood at the back of the container, with a row of four telephones in front of it. We particularly liked the angular “Trimphone”, the height of 1960s and 70s chic. You could dial the other phones in the network with a two digit number, and watch the exchange clicking in the background as you did so. Some of the sounds weren’t quite the same as the full-sized equivalents, with the various tones being replaced by vibrating reeds.

This exchange has an interesting history, being built in 1956 by “Automatic Telephone & Electric” for the Midlands Electricity Board, power generator for much of central England, where it served its commercial life. On decommissioning it went to the Ffestiniog narrow gauge railway, in Wales. He was lucky enough to learn of its existence when the Ffestiniog had no further use for it, and snapped it up.

We have to admit, we want one of these, however he makes clear that it’s an unwieldy machine that requires quite some attention so a Hackaday mechanical exchange will have to remain a dream for now.

A Treasure Trove In An English Field

June 3, 2024 by Jenny List 12 Comments

This is being written in a tent in a field in Herefordshire, one of the English counties that borders Wales. It’s the site of Electromagnetic Field, this year’s large European hacker camp, and outside my tent the sky is lit by a laser light show to the sound of electronic music. I’m home.

One of the many fun parts of EMF is its swap table. A gazebo to which you can bring your junk, and from which you can take away other people’s junk. It’s an irresistible destination which turns a casual walk into half an hour pawing through the mess in search of treasure, and along the way it provides an interesting insight into technological progress. What is considered junk in 2024?

Something for everyone

As always, the items on offer range from universal treasures of the I-can’t-believe-they-put that-there variety, through this-is-treasure-to-someone-I’m-sure items, to absolute junk. Some things pass around the camp like legends; I wasn’t there when someone dropped off a box of LED panels for example, but I’ve heard the story relayed in hushed tones several times since, and even seen some of the precious haul. A friend snagged a still-current AMD processor and some Noctua server fans as another example, and I’m told that amazingly someone deposited a Playstation 5. But these are the exceptions, in most cases the junk is either very specific to something, or much more mundane. I saw someone snag an audio effects unit that may or may not work, and there are PC expansion cards and outdated memory modules aplenty.

Finally, there is the absolute junk, which some might even call e-waste but I’ll be a little more charitable about. Mains cables, VGA cables, and outdated computer books. Need to learn about some 1990s web technology? We’ve got you covered. Continue reading “A Treasure Trove In An English Field” →

This Mobile Hackerspace Can Be Yours

June 2, 2024 by Jenny List 22 Comments

Wandering round the field at EMF Camp, our eye was caught by an unusual sight, at least to European eyes. The type of campervan body which sits on the back of a pickup truck is not particularly common on this side of the Atlantic, but there one was, fitted out as a mobile makerspace. If that wasn’t enough, this one is for sale.

Here at Hackaday we’re neither estate agents or in the want-ads business, so we’re unaccustomed to property promotion. We’re still not immune to the attraction of a portable makerspace to take to events though, and this one provides a very practical basis. It started life as what Brits call a Luton van body, a box van, and inside it’s gained a small kitchen, benches and shelves either side, and up in the space over the cab, a double bed. Sadly the laser cutter and 3D printers aren’t included.

If you live in Southern England and you want to be the envy of everyone at your next hacker camp, an email to richjmaynard at gmail dot com with a sensible offer might secure it. We would be first in the queue if we had the space, because what Wrencher scribe wouldn’t want an office like this!

Why Your Old Phone Sounded The Way It Did

June 2, 2024 by Jenny List 26 Comments

The mobile phone may be sweeping away the traditional wired phone, but that doesn’t change the fascinating history and technology of the older device. At [This Museum Is Not Obsolete] they have a fully functional mechanical telephone exchange as one of their exhibits, and they’ve published a video examining the various sounds it’s capable of making.

When a voice synthesiser was the stuff of science fiction, exchange status couldn’t be communicated by anything but a set of different tones. If you’ve ever encountered a mechanical exchange you’ll recognise the harsh-sounding low-frequency dial tone, and the various sets of beeps denoting different call status. These were produced with a set of oscillators being switched in and out by shaped cams, and the bank of these on their exchange is most of the subject of this video. The common ones such as the engaged tone and the dial tone are explained, but also some we’d never heard such as the one signifying the exchange as out of capacity.

We may never own a mechanical exchange of our own, but we’re glad that someone does and is sharing it with us. You can see the video below the break.

Continue reading “Why Your Old Phone Sounded The Way It Did” →