Reliable Frequency Reference From GPS

February 28, 2021 by Bryan Cockfield 35 Comments

GPS technology is a marvel of the modern world. Not only can we reliably locate positions on the planet with remarkable accuracy and relatively inexpensive hardware, but plenty of non-location-based features of the technology are available for other uses as well. GPS can be used for things like time servers, since the satellites require precise timing in order to triangulate a position, and as a result they can also be used for things like this incredibly accurate frequency reference.

This project is what’s known as a GPSDO, or GPS-disciplined oscillator. Typically they use a normal oscillator, like a crystal, and improve its accuracy by pairing it with the timing signal from a GPS satellite. This one is a standalone model built by [Szabolcs Szigeti] who based the build around an STM32 board. The goal of the project was purely educational, as GPSDOs of various types are widely available, but [Szabolcs] was able to build exactly what he wanted into this one including a custom power supply, simple standalone UI, and no distribution amplifier.

The build goes into a good bit of detail on the design and operation of the device, and all of the PCB schematics and source code are available on the projects GitHub page if you want to build your own. There are plenty of other projects out there that make use of GPS-based time for its high accuracy, too, like this one which ties a GPS time standard directly to a Raspberry Pi.

Randonaut Device Tells You Where To Be And When

January 28, 2021 by Lewin Day 5 Comments

Randonauting is the pastime of using random numbers to generate a destination to visit, in the pursuit of adventure. Of course, anything that can be done on a website with a script is even cooler with custom hardware, so [Decker] built a rig for the job.

The device uses a USB hardware random number generator to produce truly random numbers through quantum effects; at least, according to our best theories of the universe. These numbers are then used to pick a random set of GPS coordinates and a time in which to be there, a fun twist on traditional Randonauting of [Decker]’s own creation.

At its heart, it’s a random number generator pumped through some Python scripts. Where this build elevates itself is not in the mechanics, but the presentation. The rig runs on a Raspberry Pi, inside a bell jar, with a vacuum fluorsecent display, fairy lights and plumbing components. It plays on the cyberpunk aesthetic, and it’s so much harder to ignore one’s mission when the time and place are given in glowing numerals by an enigmatic, mysterious machine.

It looks like great fun, though beware the dangers of randonauting – some participants have found more then they bargained for. It’s not dissimilar to the old geohashing craze. Video after the break.

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Open Hardware GPS Tracker Works On Your Terms

November 28, 2020 by Tom Nardi 19 Comments

These days, there’s plenty of options if you want to get a GPS tracker for your vehicle. Unfortunately, they come with the sort of baggage that’s becoming increasingly common with consumer tech: subscription fees, third-party snooping, and a sneaking suspicion that you’re more commodity than customer. So [Viktor Takacs] decided to take things into his own hands and create an open GPS tracker designed for privacy minded hackers.

As [Viktor] didn’t want to reinvent the wheel, his design leverages several off-the-shelf modules. The core of the tracker is the ESP32, which gives him plenty of computational power while still keeping energy consumption within reasonable levels. There’s also a NEO-6M GPS receiver which works at the same 3.3 V level as the ESP32, allowing the microcontroller to read the NMEA sentences without a level shifter. He decided to go with the low-cost SIM800L GSM modem, but as it only works on 2G networks, provisions have been made in the board design to swap it out for a more modern module should you desire.

For the code to glue it all together, [Viktor] pulled in nearly a dozen open source libraries to create a feature-complete firmware that uses MQTT to create a database of location data on his personal server. From there the data is plugged into Home Assistant and visualized with Grafana. This is enough to deliver core functionality, but he says that more custom software components as well as a deep-dive into the security implications of the system is coming in the near future.

We’ve seen custom built GPS trackers before, as generally speaking, it doesn’t take a whole lot to spin up your own solution. But we think the polish that [Viktor] has put on this project takes it to the next level, and ranks it up there among some of the most impressive bespoke tracking solutions we’ve seen over the years.

Larry Berg And The Purple Open Passion Project

November 18, 2020 by Chris Lott 31 Comments

It all started with an 88-ton Arburg RP300 injection molding machine in the basement, and a bit of inattention. Larry Berg wanted a couple custom plastic plugs for his Garmin GPS, so he milled out a mold and ran a few. But he got distracted, and came back an hour later to find that his machine had made 400. Instead of throwing them away, he mailed them away for free, but then he found that people started throwing money at him to make more. People all over the world.

This is how the Purple Open Project turned into an global network of GPS geeks, selling molded alternatives to the oddball Garmin plugs for pledges to pay an unspecified amount, and ended up producing over 350,000 plugs over 16 years before he passed away in 2012. This is the story of a hacker’s hacker, who wanted to be able to connect his GPS to his computer and use it the way he wanted, and accidentally created an international business.

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Turn-by-turn Smart Glasses Give You Direction

November 14, 2020 by Al Williams 22 Comments

[SamsonMarch] designs electronic products by day and — apparently — does it in his spare time, too. His latest is a pair of really cool shades that give him turn-by-turn directions as he walks around town. Unlike some smart glasses, these get around the difficult problem of building a heads-up display by using a very simple interface based on colored LEDs visible to your peripheral vision in the temples of the frames.

The glasses themselves look great; designed in Fusion 360 and cut out of wood, no one would give them a second glance. [Sam] says you could 3D print them, too, but we think the wood looks best even if the stock is a cheap bamboo cutting board. He also cut the lenses out of acrylic.

The slots in the temples are where the action is, though. An iPhone app takes input and talks to Apple services to get directions. A lot of thought went into making the app work even though the phone keeps trying to put it to sleep. Each PCB hosts an RGB LED for indicating left/right turn and destination. They talk to the app using BLE and include accelerometers which put the boards — powered by coin cells — into sleep mode when no movement is detected.

Overall a fun and good looking project. There are even covers to hide the boards during normal use. The files you need to reproduce it are on GitHub. Usually, when we see smart glasses, they have some sort of screen which is harder to do. Of course, it is impossible to avoid comparisons to Google Glass.

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Hello From The NearSpace

November 9, 2020 by Matthew Carlson 6 Comments

A key challenge for any system headed up into the upper-atmosphere region sometimes called near space is communicating back down to the ground. The sensors and cameras onboard many high altitude balloons and satellites aren’t useful if the data they collect can’t be retrieved. Often times, custom antennas or beacons are added to help. Looking at the cost and difficulty of the problem, [arko] and [upaut] teamed up to try and make a turn-key solution for any near-space enthusiast by building CUBEX, a wonderful little module with sensors and clever radio that can be easily reused and repurposed.

CUBEX is meant as a payload for a high-altitude balloon with a camera, GPS, small battery, solar cell, and the accompanying power management circuits. The clever bit comes in the radio back down. By using the 434.460 Mhz band, it can broadcast around a hundred miles at 10mW. The only hardware to receive is a radio listener (a cheap RTL USB stick works nicely). Pictures and GPS coordinates stream down at 300 baud.

Their launch was quite successful and while they didn’t catch a solar eclipse, their balloon reached an impressive 33698m (110,560ft) while taking pictures. Even though it did eventually splashdown in the Pacific Ocean, they were able to enjoy a plethora of gorgeous photos thanks to their easy and cost-effective data link.

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Under The Sea GPS Uses Sound

November 8, 2020 by Al Williams 18 Comments

If you’ve ever tried to use GPS indoors, you know that the signals aren’t easy to acquire in any sort of structure. Now imagine trying to get a satellite fix underwater. Researchers at MIT have a new technique, underwater backscatter localization or UBL, that promises to provide a low-power localization system tailored for the subsea environment.

Like other existing solutions, UBL uses sound waves, but it avoids some of the common problems with using sonic beacons in that environment. A typical system has a fixed beacon constrained by the availability of power or battery-operated beacons that require replacement or recharging. Since the beacon acts as a transponder — it receives a signal and then replies — it requires either constant power or time to wake up from the external stimulus and that time typically varies with the environment. That variable startup time interferes with computing the round-trip time of the signal, which is crucial for estimating position.

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