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Hackaday Links: October 11, 2020

If you’re interested in SDR and digital signal processing but don’t know where to start, you’re in luck. Ben Hillburn, president of the GNU Radio Project, recently tweeted about an online curriculum for learning SDR and DSP using Python. The course was developed by Dr. Mark Lichtman, who was a lead on GNU Radio, and from the look of it, this is the place to go to learn about putting SDRs to use doing cool things. The course is chock full of animations that make the concepts clear, and explain what all the equations mean in a way that’s sure to appeal to practical learners.

It’s not much of a secret that the Hackaday community loves clocks. We build clocks out of everything and anything, and any unique way of telling time is rightly applauded and celebrated on our pages. But does the clock motif make a good basis for a video game? Perhaps not, but that didn’t stop Clock Simulator from becoming a thing. To “play” Clock Simulator, you advance the hands of an on-screen clock by pressing a button once per second. Now, thanks to Michael Dwyer, you don’t even have to do that one simple thing. He developed a hardware cheat for Clock Simulator that takes the 1PPS output from a GPS module and wires it into a mouse. The pulse stream clicks the mouse once per second with atomic precision, rendering the player irrelevant and making the whole thing even more pointless. Or perhaps that is the point.

Maybe we were a little hard on Clock Simulator, though — we can see how it would help achieve a Zen-like state with its requirement for steady rhythm, at least when not cheating. Another source of Zen for some is watching precision machining, and more precise, the better. We ran into this mesmerizing video of a CNC micro-coil winder and found it fascinating to watch, despite the vertical format. The winder is built from a CNC lathe, to the carriage of which a wire dispenser and tensioning attachment have been added. The wire is hair-fine and passes through a ruby nozzle with a 0.6 mm bore, and LinuxCNC controls the tiny back and forth motion of the wire as it winds onto the form. We don’t know what the coil will be used for, but we respect the precision of winding something smaller than a matchhead.

Dave Jones over at EEVblog posted a teardown video this week that goes to a place few of us have ever seen: inside a processor module for an IBM System/390 server. These servers earned the name “Big Iron” for a reason, as everything about them was engineered to perform. The processor module Dave found in his mailbag was worth $250,000 in 1991, and from the look of it was worth every penny. From the 64-layer ceramic substrate supporting up to 121 individual dies to the stout oil-filled aluminum enclosure, everything about this module is impressive. We were particularly intrigued by the spring-loaded copper pistons used to transfer heat away from each die; the 2,772 pins on the other side were pretty neat too.

Here’s an interesting question: what happens if an earthquake occurs in the middle of a 3D printing run? It’s probably not something you’ve given much thought, but it’s something that regular reader Marius Taciuc experienced recently. As he relates, the magnitude 6.7 quake that struck near Kainatu in Papua New Guinea (later adjusted to a 6.3 magnitude) resulted in a solid 15 seconds of shaking at his location, where he was printing a part on his modified Mendel/Prusa i2. The shaking showed up clearly in the part as the machine started swaying with the room. It’s probably not a practical way to make a seismograph, but it’s still an interesting artifact.

Tracking Your Run Over The Long Haul

The rise of smartphone and smartwatch fitness tracking has been an absolute boon for anyone interested in tracking their runs. However, it all falls short when you need a custom feature and start getting into serious long distance running, as most smartphone batteries simply won’t last. While there are devices out there for the ultra-running enthusiast, [Ivor Hewitt] decided he wasn’t willing to pay a monthly subscription for the pricy trackers or deal with the hassle of the generic cheap versions, and decided to roll his own.

The key pieces of this project are the A9G GPS module and the RDA8955 GRS/GPRS module. They’re both incredibly small and power efficient, perfect for a project that needs to be worn on your person with a long battery life. As an added bonus, the RDA8955 also includes a SoC that’s user-programmable. After battling the lackluster documentation and tooling, [Ivor] managed to get some software running on his new system. A power bug on the A9G GPS module was potentially show stopping, but thanks to some help by folks in the community, it was diagnosed and solved.

Further additions included adding a proper charging circuit (TP4056) and a beefy 2600 mAh battery scavenged from a Sony smartphone, giving the compact system around 38 hours of active battery life. An OLED screen was added to show upcoming aid stations and overall system status, driven by a custom display library. A snazzy translucent case makes the whole device slim and easy to carry. Now at the end of a long race or training session, [Ivor] has a wealth of tracked points that has already been uploaded to his own tracking website and a fully charged phone.

Next time you’re looking for a small compact GPS tracker or cellular logger take a look at this project’s code on GitHub or the A9G and RDA8955 modules.

Thanks [Ivor] for sending this one in!

A Motorcycle Dashboard Straight From The ECU

Classic motorcycles are the wild west of information displays. Often lacking even basic instrumentation such as a fuel gauge and sometimes even a speedometer, motorcycles have come a long way in instrument cluster design from even 20 years ago. There’s still some room for improvement, though, and luckily a lot of modern bikes have an ECU module that can be tapped into for some extra information as [Sophie Wheeler] illustrates with her auxiliary motorcycle dashboard.

This display is built for a modern Honda enduro, and is based upon an ESP32 module. The ESP32 is tied directly into the ECU via a diagnostic socket, unlike other similar builds that interface with a CAN bus specifically. It can monitor all of the bike’s activity including engine temperature, throttle position, intake air temperature, and whether or not the bike is in neutral. [Sophie] also added an external GPS sensor so the new display can also show GPS speed and location information within the same unit.

[Sophie] credits a few others for making headway into the Honda ECU. [Gonzo] created a similar build using a Raspberry Pi and more rudimentary screen but was instrumental in gathering the information for this build. If you’re looking for a display of any kind for your antique motorcycle which is lacking an ECU, though, we would suggest a speedometer made with nixie tubes.

Teardown: Mini GPS Jammer

If you spend enough time trolling eBay for interesting electronic devices to take apart, you’re bound to start seeing suggestions for some questionable gadgets. Which is how I recently became aware of these tiny GPS jammers that plug directly into an automotive 12 V outlet. Shipped to your door for under $10 USD, it seemed like a perfect device to rip open in the name of science.

Now, you might be wondering what legitimate uses such a device might have. Well, as far as I’m aware, there aren’t any. The only reason you’d want to jam GPS signals in and around a vehicle is if you’re trying to get away with something you shouldn’t be doing. Maybe you’re out driving a tracked company car and want to enjoy a quick two hour nap in a parking lot, or perhaps you’re looking to disable the integrated GPS on the car you just stole long enough for you to take it to the chop shop. You know, as one does.

But we won’t dwell on the potentially nefarious reasons that this device exists. Hackers have never been too choosy about the devices they investigate and experiment with, and there’s no reason we should start now. Instead, let’s take this piece of gray-area hardware for a test drive and see what makes it tick.

Continue reading “Teardown: Mini GPS Jammer”

Mobile Transmitter Gets Internal GPS And Bluetooth

While [Selim Olcer] was relatively happy with his Kenwood TM-D710a radio, he didn’t like the fact that it needed a bulky external GPS “backpack” for APRS location data. So he decided to crack open the head unit and see if he couldn’t integrate his own GPS hardware (machine translation). Not only did he succeed, but he even threw in Bluetooth compatibility for good measure.

With the repair manual circuit diagrams in hand, it was no problem to find the GPS RX and TX lines that were being broken out to the external connector. Unfortunately, the radio’s electronics are all 5 volts and the GPS module [Selim] wanted to use was only 3.3 V. So he came up with a small PCB that included not only the voltage regulator to power the GPS module, but also some voltage-dividers to level shift those signals.

Since the Kenwood TM-D710a was already designed to accept a GPS upgrade module, he just needed to change some configuration options in the radio’s menus for it to see the new hardware. Technically the project was done at this point, but since there was still room in the case and he had a GPS module spitting out NMEA sentences, [Selim] tacked on a common Bluetooth serial module so he could see the position information on his smartphone. With an application like APRSdroid, he now has a nice moving map display using the position pulled from the radio’s GPS.

With this modification done it looks like the head unit is ready to go, but that’s only the beginning for a mobile rig. Now we want to see how he integrates the whole thing into the car.

Draw On Your Lawn With This Autonomous Mower And RTK-GPS

The rise of open source hardware has seen a wide variety of laborious tasks become successfully automated, saving us humans a great deal of hassle.  Suffice to say, some chores are easier to automate than others. Take the classic case of a harmless autonomous vacuum cleaner that can be pretty dumb, bumping around the place to detect the perimeter as it traverses the room blindly with a pre-programmed sweeping pattern.

Now in principle, this idea could be extended to mowing your lawn. But would you really want a high speed rotating blade running rampant as it aimlessly ventures outside the perimeter of your lawn? The Sunray update to the Ardumower autonomous lawn mower project has solved this problem without invoking the need to lay down an actual perimeter wire. As standard consumer grade GPS is simply not accurate enough, so the solution involves implementing your very own RTK-GPS hardware and an accompanying base station, introducing centimeter-level accuracy to your mowing jobs.

RTK-GPS, also known as Carrier Phase Enhanced GPS, improves the accuracy of standard GPS by measuring the error in the signal using a reference receiver whose position is known accurately. This information is then relayed to the Ardumower board over a radio link, so that it could tweak its position accordingly. Do you need the ability to carve emojis into your lawn? No. But you could have it anyway. If that’s not enough to kick off the autonomous lawnmower revolution, we don’t know what is.

Continue reading “Draw On Your Lawn With This Autonomous Mower And RTK-GPS”

How To Choose The Right GPS Module For Your Project

You’ve built a brand new project, and it’s a wonderful little thing that’s out and about in the world. The only problem is, you need to know its location to a decent degree of accuracy. Thankfully, GPS is a thing! With an off-the-shelf module, it’s possible to get all the location data you could possibly need. But how do you go about it, and what parts are the right ones for your application? For the answers to these questions, read on! Continue reading “How To Choose The Right GPS Module For Your Project”