Positioning Without Satellites Or Base Stations

July 1, 2026 by 2 Comments

We’re all used to satellite navigation systems such as GPS or GLONASS, sheer magic in which the combination of a set of reference transmitters and super-accurate timing information can be used to calculate a position to an astounding precision. They had land based predecessors such as LORAN and Decca Navigator which worked in a similar fashion but with fixed land-based reference transmitters. Terra is an attempt to do the same thing without a network of dedicated transmitters, instead using FM broadcast transmitters as its fixed points.

This might seem like an impossible task without access to the transmitters, but they have a workaround using the Internet as a backhaul. Instead of transmitting their timing information like the systems mentioned above, they rely on a set of reference receivers sharing it online to the client’s receiver software. So far they have a demo running in Denver.

The interesting thing about this system is that it’s open-source, and requires only a relatively inexpensive software defined radio receiver and a computer to operate. Now anyone with a group of internet-connected friends to set up reference receivers can have their own positioning system, it’s no longer the exclusive preserve of governments. We like this idea, and we look forward to seeing it being tested more widely.

If you’d like to know where we’ve come from, we’ve taken a look at LORAN before.

FLOSS Weekly Episode 873: Wait, That’s Not Open Source!

July 1, 2026 by No comments

This week Jonathan chats with Andy Gryc and Aaron Basset about QNX, and the interesting Open Source history and future of that embedded OS. Why does QNX Everywhere feel more open, and why do you need to register an account to download images? All that and more — Watch to find out!

Continue reading “FLOSS Weekly Episode 873: Wait, That’s Not Open Source!” →

Review: The Tanmatsu, A Year On

July 1, 2026 by 2 Comments

About 18 months ago, we brought you a sneak peek at a handheld that started life in the Dutch conference badge scene. At the time it showed promise, but its software wasn’t ready for a fair review. Now it has both a stable operating system and a growing software library. It’s time to put it through its paces and see what it can do.

A Handheld Computer For Hackers

The Tanmatsu PCB, showing all the different parts.
The bare PCB, with the expansion connector bottom centre.

The Tanmatsu (Japanese for “Terminal”), is a general putpose palmtop computer based around an ESP32-P4 application processor from Espressif. It takes the form of a PCB and PETG 3D printed sandwich, with the front face PCB sporting a silicone QWERTY keyboard and an 800×480 MIPI DSI display. The keyboard should be familiar to many readers, being the same moulding as the Solder Party KeebDeck which has appeared on other devices.

Under the hood that P4 has two 400MHz RISC-V cores and 32MB of PSRAM with 16MB of Flash, and there’s an ESP32-C6 for WiFi, BLE and IEEE 802.15.4 mesh networking. There’s an Ebyte LoRa module with an SMA antenna too, which can be had in 868, or 915MHz versions depending on where in the world you live. Continue reading “Review: The Tanmatsu, A Year On” →

Engineering Micro-Submarines To Replace Fish

July 1, 2026 by 11 Comments

Everybody loves aquariums. There’s something soothing about watching the lil’ critters inside them swimming, crawling and wriggling about. But at the same time few people are up to the task of ensuring that said critters stay alive and happy in said aquarium. This is where small robots may be able to steal some fishy jobs, like a modern take on the gaudy fake aquariums of the 1990s. Cue [CPSDrone]’s mini-drone aquarium with mostly maintenance-free robotic fish.

These pose a few interesting engineering challenges, such as the replacing of feeding fish by having them scuttle back to their charging station like an aquatic Roomba, and giving them some level of intelligence to the point that they at least appear to be doing something fish-like.

Rather than give each robot fish full autonomy, they are instead controlled by a central system. This then raised the problem of radio frequency communication while underwater. The theory was that 433 MHz transceivers would still work for something the size of an aquarium before attenuation spoils things, which a quick test confirmed to be true.

This enabled the construction of a small microcontroller-carrying submarine as a proof of concept before diving into the final version, involving resin 3D printed enclosures that are made water-tight using rubber O-ring seals and UV-cured resin. All that was left now was to add the big control system, which takes up much of the rest of the video.

Sadly they didn’t implement the boids algorithm, as this is pretty good at creating realistic life-like motion, as show with this demonstration by [Ben Eater]. This algorithm is pretty simple, with each ‘creature’ obeying rules on coherence, separation and alignment, creating a pattern that can be observed among schools of fish as well as flocks of birds. Due to its simplicity you could conceivably even omit the central control system and just give each ‘fish’ enough sensors to keep track of its buddies.

Continue reading “Engineering Micro-Submarines To Replace Fish” →

UDP Broadcasting And Easily Finding Network Services

July 1, 2026 by 7 Comments

Local area networks (LANs) that use technologies like Ethernet and Wi-Fi are incredibly useful for letting devices talk with each other. Yet a core problem here is knowing which devices are where on the network, as anyone who has ever tried to add a network printer or network share to their system can probably attest to. Unless you happen to know the IP address of the LAN device, the port, and protocol, the target device may as well be located on the Moon without further help, such as automatic network discovery in lieu of waddling over to the device and reading the label listing its IP address.

Over the decades quite a few ways have been developed to enable such network discovery, with many of them using UDP broadcast as the first step. By broadcasting a global message on the entire LAN, any device that has an actively listening UDP socket on that particular port can parse said message and decide whether it’s feeling sociable enough to reply.

The topic of UDP broadcasting is however not as straightforward as it may sound if you’re just getting started, including the existence of many opinions on the ‘right way’. There is also a massive divide between a sprawling service discovery protocol like mDNS and a light-weight one like that one that I had to implement a few years ago for an open source project.

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Terminus Is A Text Only Phone Because Telephony Is Dead Anyway

July 1, 2026 by 11 Comments

This may say more about us than the current state of the telephone network, but unless your Grandma is still kicking, how many phone calls do you take that are actually worth picking up? Around here it’s one variety of scam or another, with the odd cold-calling salesperson to round it out.

So when we saw [Bolan Xu]’s texting-only TERMINUS cell phone project, it took but a minute to decide that, yeah, we wouldn’t miss the telephone part of the phone very much either.

The trade-offs are immense when compared to your smartphone; there’s no voice, no web browser, no social media, and no camera. But on the flip side there’s also no spyware and no annoying spam calls. Besides, he’s built a QWERTY keyboard onto this thing, and that does seem to be what most of us miss in this era of black rectangles.

In terms of electronics, its rocking a tiny OLED display for you to read your messages on, driven by an ESP8266. When WiFi is available the plan was to bridge over the internet in an SMS version of VOIP, but [Bolan Xu] ended up installing a cellular modem in it anyway.

As you can tell from the skeletal case, this is very much a prototype, but it is a promising project. We’ve seen ESP-based phones before, but they tend to be a bit smarter, and run on ESP32 instead of the more modest ESP8266.