gps

335 Articles

Train Speed Signaling Adapted For Car

September 11, 2024 by 33 Comments

One major flaw of designing societies around cars is the sheer amount of signage that drivers are expected to recognize, read, and react to. It’s a highly complex system that requires constant vigilance to a relatively boring task with high stakes, which is not something humans are particularly well adapted for. Modern GPS equipment can solve a few of these attention problems, with some able to at least show the current speed limit and perhaps an ongoing information feed of the current driving conditions., Trains, on the other hand, solved a lot of these problems long ago. [Philo] and [Tris], two train aficionados, were recently able to get an old speed indicator from a train and get it working in a similar way in their own car.

The speed indicator itself came from a train on the Red Line of the T, Boston’s subway system run by the Massachusetts Bay Transportation Authority (MBTA). Trains have a few unique ways of making sure they go the correct speed for whatever track they’re on as well as avoid colliding with other trains, and this speed indicator is part of that system. [Philo] and [Tris] found out through some reverse engineering that most of the parts were off-the-shelf components, and were able to repair a few things as well as eventually power everything up. With the help of an Arduino, an I/O expander, and some transistors to handle the 28V requirement for the speed indicator, the pair set off in their car to do some real-world testing.

This did take a few tries to get right, as there were some issues with the power supply as well as some bugs to work out in order to interface with the vehicle’s OBD-II port. They also tried to use GPS for approximating speed as well, and after a few runs around Boston they were successful in getting this speed indicator working as a speedometer for their car. It’s an impressive bit of reverse engineering as well as interfacing newer technology with old. For some other bits of train technology reproduced in the modern world you might also want to look at this recreation of a train whistle.

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Misleading GPS, Philosophy Of Maps, And You

September 10, 2024 by 19 Comments

The oft-quoted saying “all models are wrong, but some are useful” is a tounge-in-cheek way of saying that at some level, tools we use to predict how the world behaves will differ from reality in some measurable way. This goes well beyond the statistics classroom it is most often quoted in, too, and is especially apparent to anyone who has used a GPS mapping device of any sort. While we might think that our technological age can save us from the approximations of maps and models, there are a number of limitations with this technology that appear in sometimes surprising ways. [Kyle] has an interesting writeup about how maps can be wrong yet still be incredibly useful especially in the modern GPS-enabled world. Continue reading “Misleading GPS, Philosophy Of Maps, And You” →

Autonomous Boat Plots Lake Beds

August 14, 2024 by 5 Comments

Although the types of drones currently dominating headlines tend to be airborne, whether it’s hobbyist quadcopters, autonomous delivery vehicles, or military craft, autonomous vehicles can take nearly any transportation method we can think of. [Clay Builds] has been hard at work on his drone which is actually an autonomous boat, which he uses to map the underwater topography of various lakes. In this video he takes us through the design and build process of this particular vehicle and then demonstrates it in action.

The boat itself takes inspiration from sailing catamarans, which have two hulls of equal size connected above the waterline, allowing for more stability and less drag than a standard single-hulled boat. This is [Clay]’s second autonomous boat, essentially a larger, more powerful version of one we featured before. Like the previous version, the hulls are connected with a solar panel and its support structure, which also provides the boat with electrical power and charges lithium-iron phosphate batteries in the hull. Steering is handled by two rudders with one on each hull, but it also employs differential steering for situations where more precise turning is required. The boat carries a sonar-type device for measuring the water depth, which is housed in a more hydrodynamic 3d-printed enclosure to reduce its drag in the water, and it can follow a waypoint mission using a combination of GPS and compass readings.

Like any project of this sort, there was a lot of testing and design iteration that had to go into this build before it was truly seaworthy. The original steering mechanism was the weak point, with the initial design based on a belt connecting the two rudders that would occasionally skip. But after a bit of testing and ironing out these kinks, the solar boat is on its way to measure the water’s depths. The project’s code as well as some of the data can be found on the project’s GitHub page, and if you’re looking for something more human-sized take a look at this solar-powered kayak instead.

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A Super-Simple Standalone WSPR Beacon

June 14, 2024 by 26 Comments

We’ve said it before and we’ll say it again: being able to build your own radios is the best thing about being an amateur radio operator. Especially low-power transmitters; there’s just something about having the know-how to put something on the air that’ll reach across the planet on a power budget measured in milliwatts.

This standalone WSPR beacon is a perfect example. If you haven’t been following along, WSPR stands for “weak-signal propagation reporter,” and it’s a digital mode geared for exploring propagation that uses special DSP algorithms to decode signals that are far, far down into the weeds; signal-to-noise ratios of -28 dBm are possible with WSPR.

Because of the digital nature of WSPR encoding and the low-power nature of the mode, [IgrikXD] chose to build a standalone WSPR beacon around an ATMega328. The indispensable Si5351 programmable clock generator forms the RF oscillator, the output of which is amplified by a single JFET transistor. Because timing is everything in the WSPR protocol, the beacon also sports a GPS receiver, ensuring that signals are sent only and exactly on the even-numbered minutes. This is a nice touch and one that our similar but simpler WSPR beacon lacked.

This beacon had us beat on performance, too. [IgrikXD] managed to hit Texas and Colorado from the edge of the North Sea on several bands, which isn’t too shabby at all with a fraction of a watt.

Thanks to [STR-Alorman] for the tip.

[via r/amateurradio]

Console Calculator Moves One Step Closer To Original Design

May 24, 2024 by 14 Comments

With smartphone apps and spreadsheets being the main ways people crunch their numbers nowadays, there’s not much call for a desktop calculator. Or any other physical calculator, for that matter. Which is all the more reason to appreciate this  Wang 300-series calculator console’s revival through a new electronic backend.

If you haven’t made the acquaintance of the Wang calculator series, [Bob Alexander]’s previous Wang project is a perfect introduction. Despite looking very much like an overbuilt early-70s desktop calculator, what you see in the video below is just a terminal, one of four that could connect to a shared “Electronics Package” where most of the actual computational work was done. The package was big and is currently hard to come by, at least at a reasonable price, but the consoles, with their Nixie displays and sturdy keypads, are relatively abundant.

[Bob]’s previous venture into reviving his console involved embedding a PIC32-based controller, turning it into the standalone desktop calculator it never was. To keep more with the original design philosophy, [Bob]’s second stab at the problem moves much of the same circuitry from inside the console into a dedicated outboard package, albeit one much smaller than the original. The replacement package extends and enhances the console functionality a bit, adding a real-time clock and a Nixie exercise routine to ward off the dreaded cathode poisoning. [Bob] also recreates the original Wang logarithmic method of multiplication and division, which is a nice touch with its distinctive flashing display.

Seeing the Wang console hooked up to a package through that thick cable and Centronics connector is oddly satisfying. We’d love to see [Bob] take this to the logical extent and support multiple consoles, but that might be pushing things a bit.

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[Scott Manley] Explains GPS Jamming

May 19, 2024 by 46 Comments

We always think of [Scott Manley] as someone who knows a lot about rockets. So, if you think about it, it isn’t surprising he’s talking about GPS — after all, the system uses satellites. GPS is used in everything these days, and other forms of navigation are starting to fall by the wayside. However, the problem is that the system is vulnerable to jamming and spoofing. This is especially important if you fear GPS allowing missiles or drones to strike precise targets. But there are also plenty of opportunities for malicious acts. For example, drone light shows may be subject to GPS attacks from rival companies, and you can easily imagine worse. [Scott] talks about the issues around GPS spoofing in the video, which you can see below.

Since GPS satellites are distant, blocking the signal is almost too easy, sometimes happening inadvertently. GPS has technology to operate in the face of noise and interference, but there’s no way to prevent it entirely. Spoofing — where you produce false GPS coordinates — is much more difficult.

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GPS At Any Speed

May 13, 2024 by 39 Comments

[Mellow_Labs] was asked to create a GPS speedometer. It seems simple, but of course, the devil is in the details. You can see the process and the result in the video below.

We have to admit that he does things step-by-step. The first step was to test the GPS module’s interface. Then, he tried computing the speed from it and putting the result on a display. However, testing in the field showed that the display was not suitable for outdoor use.

That prompted another version with an OLED screen. Picking the right components is critical. It struck us that you probably need a fast update rate from the GPS, too, but that doesn’t seem to be a problem. Continue reading “GPS At Any Speed” →