Cosmic Ray Navigation

GPS is a handy modern gadget — until you go inside, underground, or underwater. Japanese researchers want to build a GPS-like system with a twist. It uses cosmic ray muons, which can easily penetrate buildings to create high-precision navigation systems. You can read about it in their recent paper. The technology goes by MUWNS or wireless muometric navigation system — quite a mouthful.

With GPS, satellites with well-known positions beam a signal that allows location determination. However, those signals are relatively weak radio waves. In this new technique, the reference points are also placed in well-understood positions, but instead of sending a signal, they detect cosmic rays and relay information about what it detects to receivers.

The receivers also pick up cosmic rays, and by determining the differences in detection, very precise navigation is possible. Like GPS, you need a well-synchronized clock and a way for the reference receivers to communicate with the receiver.

Muons penetrate deeper than other particles because of their greater mass. Cosmic rays form secondary muons in the atmosphere. About 10,000 muons reach every square meter of our planet at any minute. In reality, the cosmic ray impacts atoms in the atmosphere and creates pions which decay rapidly into muons. The muon lifetime is short, but time dilation means that a short life traveling at 99% of the speed of light seems much longer on Earth and this allows them to reach deep underground before they expire.

Detecting muons might not be as hard as you think. Even a Raspberry Pi can do it.

Adding Variometer Functionality To A GPS

Flying a glider, or similarly piloting a paraglider or hang glider, can all be pathways into aviation with a lower barrier of entry than powered flight. Sacrificing one’s engine does generate a few complexities, but can be rewarding as the pilot searches for various means of increasing altitude like ridge soaring or thermaling. You’ll need a special instrument called a variometer to know just how much altitude you’re gaining though, like this one which is built into commercially-available handheld GPS units.

These GPS units are normally intended for use on terra firma only, but [Oganisyan] has figured out a clever way to add this flight instrumentation to these units to help when operating a paraglider. An ATmega328 paired with a pressure sensor is added to the inside of the GPS units and communicates with an available serial interface within the units. To complete the modification, a patched firmware must be installed which adds the variometer function to the display. This upgrade is compatible with a handful of GPS units as well such as the BikePilot2+ or Falk Tiger.

For those who already own one of these GPS units, this could be a cost-effective way of obtaining a variometer, especially since commercially-available variometers tailored for this sort of application can cost around $200 to $500. It is an activity sensitive to cost, though, as it offers a much more affordable option for taking to the skies than any powered craft could, with an exception made for this powered paraglider which offers the ability for powered take off and flight extension using electric-powered props.

Thanks to [MartinO] for the tip!

Developing An Open Source Bike Computer

While bicycles appear to have standardized around a relatively common shape and size, parts for these bikes are another story entirely. It seems as though most reputable bike manufacturers are currently racing against each other to see who can include the most planned obsolescence and force their customers to upgrade even when their old bikes might otherwise be perfectly fine. Luckily, the magic of open source components could solve some of this issue, and this open-source bike computer is something you’ll never have to worry about being forced to upgrade.

The build is based around a Raspberry Pi Zero in order to keep it compact, and it uses a small 2.7 inch LCD screen to display some common information about the current bike ride, including location, speed, and power input from the pedals. It also includes some I2C sensors including pressure and temperature as well as an accelerometer. The system can also be configured to display a map of the current ride as well thanks to the GPS equipment housed inside. It keeps a log in a .fit file format as well so that all rides can be archived.

When compared against a commercial offering it seems to hold up pretty well, and we especially like that it’s not behind a walled garden like other products which could, at any point, decide to charge for map upgrades (or not offer them at all). It’s a little more work to set up, of course, but worth it in the end. It might also be a good idea to pair it with other open source bicycle components as well.

Thanks to [Richard] for the tip!

Garmin HUD Got Discontinued, But Not Trashed

The Garmin HUD+ was a small Bluetooth device intended for the dashboard of a car, meant to be used as a GPS heads-up display for data from Garmin smartphone apps. It used a bright VFD (vacuum fluorescent display) which was viewed through a clear reflector, and displayed GPS information and directions. It was discontinued in 2015, but [Doz] was fond of his and used it happily until a phone upgrade meant it no longer worked. Was it destined for a landfill? Not if he had anything to say about it!

The first thing [Doz] tried was using an alternate Android app, but since it also didn’t work, it was time to sit back and reflect on the scope of the issue. In [Doz]’s case, he really only wanted some basic meaningful data displayed, and decided he could do away with the phone altogether if he had the right hardware. Continue reading “Garmin HUD Got Discontinued, But Not Trashed”

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Hackaday Links: October 23, 2022

There were strange doings this week as Dallas-Forth Worth Airport in Texas experienced two consecutive days of GPS outages. The problem first cropped up on the 17th, as the Federal Aviation Administration sent out an automated notice that GPS reception was “unreliable” within 40 nautical miles of DFW, an area that includes at least ten other airports. One runway at DFW, runway 35R, was actually closed for a while because of the anomaly. According to GPSjam.org — because of course someone built a global mapping app to track GPS coverage — the outage only got worse the next day, both spreading geographically and worsening in some areas. Some have noted that the area of the outage abuts Fort Hood, one of the largest military installations in the country, but there doesn’t appear to be any connection to military operations. The outage ended abruptly at around 11:00 PM local time on the 19th, and there’s still no word about what caused it. Loss of GPS isn’t exactly a “game over” problem for modern aviation, but it certainly is a problem, and at the very least it points out how easy the system is to break, either accidentally or intentionally.

In other air travel news, almost as quickly as Lufthansa appeared to ban the use of Apple AirTags in checked baggage, the airline reversed course on the decision. The original decision was supposed to have been based on “an abundance of caution” regarding the potential for disaster from its low-power transmitters, or should a stowed AirTag’s CR2032 battery explode. But as it turns out, the Luftfahrt-Bundesamt, the German civil aviation authority, agreed with the company’s further assessment that the tags pose little risk, green-lighting their return to the cargo compartment. What luck! The original ban totally didn’t have anything to do with the fact that passengers were shaming Lufthansa online by tracking their bags with AirTags while the company claimed they couldn’t locate them, and the sudden reversal is unrelated to the bad taste this left in passengers’ mouths. Of course, the reversal only opened the door to more adventures in AirTag luggage tracking, so that’s fun.

Energy prices are much on everyone’s mind these days, but the scale of the problem is somewhat a matter of perspective. Take, for instance, the European Organization for Nuclear Research (CERN), which runs a little thing known as the Large Hadron Collider, a 27-kilometer-long machine that smashes atoms together to delve into the mysteries of physics. In an average year, CERN uses 1.3 terawatt-hours of electricity to run the LHC and its associated equipment. Technically, this is what’s known as a hell of a lot of electricity, and given the current energy issues in Europe, CERN has agreed to shut down the LHC a bit early this year, shutting down in late November instead of the usual mid-December halt. What’s more, CERN has agreed to reduce usage by 20% next year, which will increase scientific competition for beamtime on the LHC. There’s only so much CERN can do to reduce the LHC’s usage, though — the cryogenic plant to cool the superconducting magnets draws a whopping 27 megawatts, and has to be kept going to prevent the magnets from quenching.

And finally, as if the COVID-19 pandemic hasn’t been weird enough, the fact that it has left in its wake survivors whose sense of smell is compromised is alarming. Our daily ritual during the height of the pandemic was to open up a jar of peanut butter and take a whiff, figuring that even the slightest attenuation of the smell would serve as an early warning system for symptom onset. Thankfully, the alarm hasn’t been tripped, but we know more than a few people who now suffer from what appears to be permanent anosmia. It’s no joke — losing one’s sense of smell can be downright dangerous; think “gas leak” or “spoiled food.” So it was with interest that we spied an article about a neuroprosthetic nose that might one day let the nasally challenged smell again. The idea is to use an array of chemical sensors to stimulate an array of electrodes implanted near the olfactory bulb. It’s an interesting idea, and the article provides a lot of fascinating details on how the olfactory sense actually works.

When [Elon] Says No, Just Reverse Engineer The Starlink Signal

We all know that it’s sometimes better to beg forgiveness than ask permission to do something, and we’ll venture a guess that more than a few of us have taken that advice to heart on occasion. But [Todd Humphreys] got the order of operations a bit mixed up with his attempt to leverage the Starlink network as a backup to the Global Positioning System, and ended up doing some interesting reverse engineering work as a result.

The story goes that [Todd] and his team at the University of Texas Austin’s Radionavigation Lab, on behalf of their sponsors in the US Army, approached Starlink about cooperating on a project to make their low-Earth orbit constellation provide position, navigation, and timing capabilities. Although initially interested in the project, Starlink honcho [Elon Musk] put the brakes on things, leaving [Todd]’s team high and dry. Not to be dissuaded, they bought a Starlink user terminal, built what amounts to a small radiotelescope — although we’ve seen something similar done with just an RTL-SDR — and proceeded to reverse-engineer the structure of Starlink’s Ku-band downlink signal. The paper (PDF link) on their findings is densely packed with details, such as the fact that Starlink uses an orthogonal frequency-division multiplexing (OFDM) scheme.

It’s important to note that their goal was not to break encryption or sniff in on user data; rather, they wanted access to the synchronization and timing signals embedded in the Starlink data structures. By using this data along with the publically available ephemera for each satellite, it’s possible to quickly calculate the exact distance to multiple satellites and determine the receiver’s location to within 30 meters. It’s not as good as some GPS-Starlink hacks we’ve seen, but it’s still pretty good in a pinch. Besides, the reverse engineering work here is well worth a read.

Thanks to [Adrian] for the tip!

TickTag, a tiny GPS logger with 3d printed case, LiPo battery and a 1 Euro coin for size reference

Tiny GPS Logger For The Internet Of Animals

[Trichl] has created a tiny GPS logger, called ‘TickTag’, designed as an inexpensive location tracking option for animal studies. The low cost, tiny form factor, and large power density of the LiPo battery give it the ability to track large populations of small animals, including dogs and bats.

The TickTag is capable of getting 10,000 GPS fixes from its 30 mAh cell. Each unit is equipped with an L70B-M39 GPS module controlled by an Atmel ATtiny1626 microcontroller and sports a tiny AXE610124 10-pin connection header for programming and communication. GPS data is stored on a 128 kB EEPROM chip with each GPS location fix using 25 bits for latitude, 26 bits for longitude, and 29 bits for a timestamp. Add it all up and you get 10 bytes per GPS data point (25+26+29=80), giving the 10k GPS fix upper bound.

To record higher quality data and extend battery life, the TickTag can be programmed to record GPS location data using variable frequency intervals or when geofencing bounds have been crossed.

Continue reading “Tiny GPS Logger For The Internet Of Animals”