From Phone, To SDR, No Extra Hardware

November 9, 2026 by No comments

One of the more exciting recent developments has been the discovery that many radio chips used in common and cheap wireless network interfaces, microcontrollers, LoRa interfaces and others can be persuaded to give access to their baseband data streams This gives them full SDR functionality, which on cheap devices is hugely interesting. Continuing that trend and taking it to a new height is [Logan Zarov], who’s converted an LG D325 Android phone into a wideband receiver with very minor modification indeed.

The phone is rooted and runs LineageOS as you might expect, and there’s a modem firmware update to supply the SDR baseband magic. There’s also a mod for an antenna wire. Where this becomes especially interesting is in its receive frequency range. The modem talks in the GHz, but this radio receives in the MHz, it can pick up shortwave. This is achieved by using the Bluetooth radio as a local oscillator, oddly in a similar manner to that we suggested a few weeks ago.

This is hackery at its most epic, we love it, and look forward to the similar hacks which will certainly follow. There’s a video below the break, and you can see it doing its thing.

Continue reading “From Phone, To SDR, No Extra Hardware” →

UDP Broadcasting Meets The More Focused Multicasting

November 9, 2026 by No comments

After previously exploring the basics of UDP broadcasting, why IPv4 subnets are an exciting feature that you really want to dive into, as well as the contentious topic of IPv6, there are still plenty of elephants to admire and cans of sardines to crack open. One of them being the topic of broadcasting versus multicasting, which at first glance sounds rather similar and may even have some wondering why you’d even bother with multicasting if you can just send-and-forget with IPv4 broadcast address.

Of course, we already found out that IPv4 broadcast addresses come in a few flavors, and that’s before you start even considering the implications of subnets and routing limits. When we then consider that in IPv6 broadcast addresses were dropped completely in favor of link-local multicast addresses, and that IPv4 also supports multicast, then this raises the question whether using IPv4 multicast’s own take on ‘link-local’ doesn’t make more sense.

Or perhaps more succinctly put, is IPv4’s take on link-local broadcasting as straightforward as IPv6’s?

Continue reading “UDP Broadcasting Meets The More Focused Multicasting” →

Reverse Engineering A 1960s Diode-Transistor Logic IC

November 9, 2026 by 4 Comments

Before transistor-transistor logic (TTL) took over, diode-transistor logic (DTL) was a common sight especially in pre-IC circuits where it was a major improvement over resistor-transistor logic (RTL). That said, it’s rare to see DTL used in ICs considering how e.g. TI’s 5400 and 7400 series set the trend in the 1960s. This makes the Signetics ST680a quad-NAND gate DTL DIP IC that [Ken Shirriff] ogled recently a bit of a treat.

This was also one of the earliest ICs to use the then brand new plastic dual in-line package (PDIP) for modular convenience, even if [Ken] was none too happy about as unlike ceramic DIP, PDIP requires more extreme methods to decap to access the die for reverse-engineering.

Overall, TTL is faster and less power-hungry than DTL, but it took a while to work out its issues, including noise immunity and fan-in/out issues. Until then alternatives like DTL still made sense as a well-understood and mature technology. In the article an example is provided of how a DTL NAND gate as used in this IC works, which is really quite simple in how it uses multiple diodes to sum the inputs, which subsequently drives the transistors.

We’d like to thank [CuriousMarc] for finding this IC in his strategic reserve of unknown ICs and for doing the initial decapping using hot air, as well as [Ken] for doing the analysis and documenting of this fascinating glimpse into early semiconductor logic history.

Radon Active

November 9, 2026 by 16 Comments

When you think about nuclear radiation, you often think about power plants, but it turns out there’s radioactive stuff all over the place: smoke detectors, granite counters, bananas, and potatoes can all be mildly radioactive. Even some old tape dispensers. But those are all puny sources.

Radon is a colorless, odorless gas that is heavier than air. It is a byproduct of uranium decay, amonth other pathways, decays by emitting an alpha particle, and has a half-life of just about four days. As a gas, it escapes from rocks or soil. Usually, there isn’t much of it, so it vents harmlessly to the atmosphere. But it can easily get trapped in a house and accumulate. You might think your house is solid, but there are plenty of cracks, joints, and pipes where gas can weasel through, especially if your inside pressure is slightly lower than the pressure in the soil below, which is common.

As the radon decays, it can produce more radioactive material, including tiny amounts of polonium. With or without dust particles, these tiny bits of radioactive material can go airborne and end up in your lungs. There, they can further decay, and alpha particles damage cells and DNA. According to the EPA, radon exposure is the second leading cause of lung cancer in the United States, next to smoking.

Not So Speedy

If you get enough carbon monoxide in your home, you probably won’t see the next sunrise. But radon works very slowly. It is odorless and colorless. You won’t show any general symptoms to warn you that you might get lung cancer.

The effect can take years or decades. Of course, you can also have a house that has very little radon. However, nearly all homes have some radon. The EPA estimates that about 7% of homes have elevated radon levels.

Some areas are more prone to radon than others, but even if your area has low risk, there’s no guarantee that your house is safe. If you are lucky enough to not have a radon problem, you have nothing to worry about. But how do you know? Like anything, you need to test.

Continue reading “Radon Active” →

Web Satellite Tracker Plays The Music Of The Spheres

November 9, 2026 by 2 Comments

There are a dizzying number of satellites in orbit around the Earth these days, and more are being added at an incredible rate. Those of us with an interest in space are aware of this on a conceptual level, but it’s still difficult to put into human terms. If you’re having trouble wrapping your head around the traffic buzzing overhead, perhaps the new feature on OrbitalWiki which turns satellite overflights into live music may help.

Given your location, or at least an approximation of it, OrbitalWiki can determine which of the nearly 17,000 satellites it’s currently tracking are flying over you in real-time. When each satellite hits the highest point in the sky from your perspective, it will play a single note.

The synthesized instrument and octave of each note is determined by the orbital parameters of the specific vehicle, so each one will sound slightly different. The result is a slow, sort of ambient soundscape that’s surprisingly relaxing given the “artists” are screaming around our planet at several miles per second. Since the orbits of the craft are known and predictable, you have the option of cranking up the timescale if you’d like to hear something a bit more energetic.

If you’re looking for more emergent musical content, check out [Sam Scorsby]’s fascinating project Impermanence Series A, which stitches songs together from snippets of global radio broadcasts.

An audio spectrogram is shown in the middle of the image, with intensity plots shown both above and below the spectrogram. A vertical yellow line runs through all three graphs.

Determining Location By Listening For Airplanes

November 9, 2026 by 24 Comments

Beyond what people deliberately disclose, there’s a surprising amount of information hidden in everyday messages, especially photos and videos. Even when people try to hide the location or time at which something was recorded, small details make these surprisingly difficult to obscure. One of the more well-known techniques correlates mains-frequency hum with power grid frequency variations. In a similar vein, [colsto] recently developed a powerful technique for precisely geolocating videos using the Doppler curves generated by passing aircraft.

Since aircraft are often audible for miles in all directions, they’re particularly likely to be inadvertently picked up in a video. The aircraft may not be discernible to the human ear, but the sound it makes can still show up in a spectrogram. To turn this data into a location, the pattern of Doppler curves needs to be correlated to an aircraft’s flight path. This is easy enough using public ADS-B records, which provide a timestamped history of each aircraft’s location, altitude, speed, and heading.

Having more than one Doppler curve in the recording simplifies the location process significantly: it’s possible to simply search for points at which Doppler curves would have been heard with the correct interval between them. It’s also important to exclude locations at which more Doppler curves would have been heard than were actually recorded – without this filter, most locations are around airports.

This eliminates most candidate areas, but it still leaves too many to manually check. The shape of the Doppler curve also provides a clue, though. The height of the curve is determined by the airplane’s speed, and the length by its distance. From an aircraft’s flight path, it’s possible to reconstruct the Doppler curve which would have been heard at any point around its flight path. These reconstructions can then be matched against the real curve to find the exact location. In a test, even a single Doppler curve was enough to locate a video without the help of any other clues.

This is just the latest in a long series of unexpected ways in which we’ve seen secrets shared, whether the secret in question is the location of a military base or the position of radar emitters.

Continue reading “Determining Location By Listening For Airplanes” →

A Smart Alarm Clock That Doesn’t Sell Your Soul

November 8, 2026 by 12 Comments

Devices from the likes of Google and Amazon can be used as high-tech alarm clocks that can show the weather and family photos in addition to telling you what time it is. But they’re also used to push ads out and potentially do other shady things that you’d probably just as soon not have in your bedroom.

If you like the features offered by devices like these but not the hidden costs that come with them, take a look at Rouse. This firmware, which can be installed on common ESP32 development boards such as the Waveshare ESP32-S3-Touch and the ubiquitous Cheap Yellow Display, provides some of those same features in a DIY package.

There’s no user account, no subscription, and no app for your phone that will inevitably stop working some day. The firmware offers up a web interface for configuration that can be accessed by anything with a web browser, and while it can perform firmware updates over the network, it only does so with your approval. It might seem odd that we have to double check to make sure our alarm clocks aren’t leaking any of our information onto the Internet, but that’s the world we live in apparently.

In addition to the basic ESP32 board, you’ll probably want to add some buttons and a speaker, all of which is documented in a fantastic build guide. There’s even files for you to 3D print your own enclosure for the finished clock, though you could certainly put it in an enclosure of your own choosing should you want to customize the build further.

Hackers and makers love clock projects, and at this point we’ve covered more than we can even keep track of. As part of that we’ve seen a number of alarm clocks builds, but as is so often the case around these parts, they tend to be one-off builds. The fact that Rouse has been built with community in mind really makes it stand out, and we’d love to hear in the comments if any of you already have one of these ticking away on your nightstand.