So You Want To Make Your SDR Work On Other Frequencies

Perhaps the most exciting news of the past few weeks in the world of hardware hacking has been the unlocking of hidden SDR functionality in the Wi-Fi radios found on Espressif ESP32 microcontrollers. They can be used as both transmit and receive SDRs, and given that it’s early days for this hack we expect that great things are yet to come.

There’s one snag though, despite speculation that they might be dragged down to much lower frequencies, as far as we know they’re only proven to work around the Wi-Fi frequencies. Though the reality may be wider we’ll take that for a 2.4 GHz part as a 100 MHz slice from 2.4 GHz to 2.5 GHz. Plenty of possibilities there, and they might even work down to 1.8 GHz, but there would be so much more to do if it could work elsewhere in the spectrum. So it’s time to look at the converter, a tried and tested old way to make a radio work on a different frequency.

Continue reading “So You Want To Make Your SDR Work On Other Frequencies” →

Fixing A Power Grid That Loses Over Half Its Power To Inefficiency And Theft

[Mini Shaji Thomas] has a deeply interesting article on IEEE Spectrum detailing how the power distribution system for a city of over twenty million people went from failing to first-class. In the early 2000s, over half of Delhi’s generated power was lost to inefficiencies of all kinds, and theft. Losses were technical as well as administrative, and the rampant theft was perpetuated by “both the powerful and the powerless”. Spoiler alert: it’s a big job.

That level of loss is staggering, and caused by many issues rather than just one or two. Many of the problems tended to compound one another. For example, an effective power grid relies on balancing active and reactive power, but if that is not well managed then inefficiencies cause losses and outages that tend to lead to even more losses and outages as the system is never able to catch up to demand. On the scale of tens of millions of inhabitants, such losses are far from trivial.

There wasn’t a silver bullet solution. Modernizing and stabilizing the power distribution required technical resources, modernized equipment, political will, expert planning, a willingness to follow through, and authority.

The starting point was grim: a failing network that was constantly overloaded, poor or nonexistent controls and safeguards, inaccurate records and inefficient administration, no real means of sensing faults or inefficiencies or theft, weak to nonexistent enforcement, and an untrained workforce. Still, it could be done, and it was. While there’s still improvement to be made, revamping the system was ultimately successful.

Individually, some of the solutions were quite simple. For example, replacing bare overhead distribution wires with a system of insulated cables containing multiple conductors was not just safer and more resilient, it made it much harder for people to tap into the lines. Other initiatives like making it easier and more convenient to pay accurate bills helped, too. Turns out it’s easier to have legit customers when the product and service is reliable.

Give it a read if you have a few minutes, because besides providing a peek into the technical end of how effective power grids work, it’s a good analysis of what can be accomplished with some co-operation and a willingness to change.

Roman Telescope Saves Fuel, Doubles Mission

Contemplate the events that might end a space mission, and you might picture something dramatic: detonation on the pad, a dead guidance system, or micrometeoroids shattering delicate solar panels. More often, though, the ending is far more mundane. Plenty of perfectly healthy spacecraft have been retired simply because the fuel tanks ran dry. That’s why mission planners guard every kilogram of go juice so jealously, and why careful preparation in a mission is critical to long-term success.

Which brings us to NASA’s Nancy Grace Roman Space Telescope. Barely two weeks after its August 30 launch on a Falcon Heavy, the mission team announced that Roman now has enough fuel for at least 22 years of science operations. That’s well over double its original 10-year fuel budget. It’s a huge gain, so let’s explore how NASA pulled it off.

Continue reading “Roman Telescope Saves Fuel, Doubles Mission” →

Raspberry Pi RAM Restrictions No Big Deal, Frankly

Hacking on Raspberry Pi board internals is one of my favourite topics. I know a bunch of obscure things about these cute little boards. Three years ago, I covered a Raspberry Pi 4 RAM upgrade story. Getting a BGA RAM chip and swapping it in seemed like a no-brainer to me – apart from all the numerous uncertain parts about it, you know. It was a joy to see hackers pull it off, and for it to function as well as it did!

Things changed. You can’t really get RAM chips anymore. You also can’t get RAM sticks. You can’t get even SSDs with RAM chips on them. Even getting Raspberry Pi boards can be hard unless you know where to look. This is where a recent three-minute video by [Jeff Geerling] finds us.

Turns out, Raspberry Pi Foundation pushed binary-blob bootloader changes that limit your ability to upgrade RAM. I’ve known about it since last year through the grapevine, and somehow, as I read about it, this didn’t bother me at all. Not enough to write a Hackaday article about it, even, much less talk about it more widely. Why didn’t it bother me? Today, I sat down and pondered this for a bit.

Here’s my conclusion: I don’t think it’s a big deal at all, even if it seems that many people would disagree. Come in, as you are, and I hope you find my thoughts on the situation entertaining.

Continue reading “Raspberry Pi RAM Restrictions No Big Deal, Frankly” →

The First Floating Nuclear Power Station

Nuclear power really hit its stride in the 1950s. In the post-war period, there was a rush to develop peaceful uses for splitting the atom, beyond its application as a weapon of war. Soon enough, nuclear reactors were hooking up to power grids and helping propel ships and submarines around the globe.

Eventually, this led to an obvious idea—what if a ship with a reactor could serve as a floating nuclear power station? That question would be answered in the mid-1960s, with an American project of some strategic importance.

Continue reading “The First Floating Nuclear Power Station” →

What’s Mu Metal?

If you tear into old TVs or recording equipment, you may see shields made from some exotic-looking metal. Old timers will tell you it’s called mu metal, and its purpose is to — sort of — shield things from magnetic fields. The qualification is important. Unlike a conductive RF shield, mu metal doesn’t really stop a magnetic field. Instead, it gives magnetic flux an easier path to follow around whatever you’re trying to protect.

What’s In The Metal?

Mu metal belongs to a family of soft magnetic nickel-iron alloys. A typical modern formulation is about 80% nickel and 15% iron, with molybdenum and a few other elements making up most of the remainder. What makes it useful is its extremely high magnetic permeability. Commercial material can have relative permeability around 100,000 or more, and some specialty alloys can reach even higher.

You can think about reluctance as the magnetic equivalent of resistance. Put a high-permeability shell around something sensitive, and magnetic flux would much rather travel through the shell than through the space inside it, just like current tends to take the path of least resistance.

This works particularly well for DC and low-frequency fields, exactly where your usual copper or aluminum EMI shield isn’t much help.

Continue reading “What’s Mu Metal?” →

Australia’s Nationwide Phone Outage Was An Embarrassing Failure

The phones! They were one of the basic utilities of the 20th century, and were just about as reliable as death and taxes. Even when then power grid went down, you still had a fair shot of getting a phone call through thanks to the reliability of the Plain Old Telephone Service.

Today, we eschew the simplicity of copper and mechanical switches for the supreme bandwidth and capability of high-speed cellular connectivity. With that, we accept that the additional complexity comes with a risk of complicated failures that bring everything tumbling down. Australia’s largest telecommunications provider found that out to its peril just a few short months ago.

Continue reading “Australia’s Nationwide Phone Outage Was An Embarrassing Failure” →