Misleading GPS, Philosophy of Maps, And You https://hackaday.com/2024/09/10/misleading-gps-philosophy-of-maps-and-you/ #approximation #precision #gpshacks #accuracy #mapping #garmin #Strava #model #gps #map
#gpshacks
A Homebrew GPS Correction System for DIY Land Surveying https://hackaday.com/2024/01/12/a-homebrew-gps-correction-system-for-diy-land-surveying/ #real-timekinematics #cartography #correction #mapmaking #surveying #gpshacks #satnav #NTRIP #gnss #gps #map #RTK
Designing a PCB GPS Antenna From Scratch https://hackaday.com/2023/10/18/designing-a-pcb-gps-antenna-from-scratch/ #circularpolarization #patchantenna #simulation #gpshacks #PCBHacks #flatcam #badge #KiCAD #gps #pcb
Mapping the Depths with an Autonomous Solar Boat https://hackaday.com/2023/07/23/mapping-the-depths-with-an-autonomous-solar-boat/ #autonomousboat #depthmapping #RobotsHacks #greenhacks #gpshacks #solar #sonar
Knowing Your Place: The Implications Of GPS Spoofing And Jamming
Artificial satellites have transformed the world in many ways, not only in terms of relaying communication and for observing the planet in ways previously inconceivable, but also to enable incredibly accurate navigation. A so-called global navigation satellite system (GNSS), or satnav for short, uses the data provided by satellites to pin-point a position on the surface to within a few centimeters.
The US Global Positioning System (GPS) was the first GNSS, with satellites launched in 1978, albeit only available to civilians in a degraded accuracy mode. When full accuracy GPS was released to the public under the 1990s Clinton administration, it caused a surge in the uptake of satnav by the public, from fishing boats and merchant ships, to today's navigation using nothing but a smartphone with its built-in GPS receiver.
Even so, there is a dark side to GNSS that expands beyond its military usage of guiding cruise missiles and kin to their target. This comes in the form of jamming and spoofing GNSS signals, which can hide illicit activities from monitoring systems and disrupt or disable an enemy's systems during a war. Along with other forms of electronic warfare (EW), disrupting GNSS signals form a potent weapon that can render the most modern avionics and drone technology useless.
With this in mind, how significant is the threat from GNSS spoofing in particular, and what are the ways that this can be detected or counteracted?
Ephemeral Positioning
GPS autonomous positioning using the satellite navigation solution (Credit: Jan van Sickle, GPS for Land Surveyors)
The basic concept of a GNSS is fairly straight-forward: ground-based receivers listen for the signals from the satellites that are part of the specific GNSS constellation. Each GNSS satellite encodes a collection of information into this signal, which includes the position (ephemeris) of the satellite at a given time, as well as the local time on the satellite when the signal was sent.
By taking the signals from at least four of these satellites and applying the satellite navigation solution, the absolute position of the receiver can thus be determined. This uses the principle of trilateration (distance to a known point) rather than triangulation (using angles). As can be surmised, a potential issue here involves clock drift on the side of the receiver and the satellites. Perhaps less expected is that the travel speed of the signal is also heavily affected by the atmosphere, specifically the ionosphere.
This part of the atmosphere changes in thickness and composition over the course of a day, and is heavily affected by exposure to the Sun's radiation. As a result, part of the GNSS satellite's message contains the required atmospheric correction parameters. Because of clock-drift and the constant changes to the Earth's atmospheric composition, each GNSS constellation has its own augmentation system. These generally consist out of a combination of ground- and satellite-based systems that provide additional information that a receiver can use to adjust the GNSS information it has received.
For use with airplane navigation, for example, it is very common to have a ground-based augmentation system (GBAS) installed using fixed receivers. These GNSS receivers then broadcast correction parameters via the airport's VHF communication system to the airplane, helping them navigate when they approach or depart the airport.
In addition to the GNSS satellites themselves, each GNSS constellation also has its own ground-based master controller station, from which updated information on atmospheric conditions is regularly uploaded to the satellites, along with time adjustments to compensate for the satellite's onboard clock drift. This demonstrates that a GNSS constellation is a highly dynamic system which requires constant updates in order to function properly.
Where things get interesting, however, is when attempts are made to circumvent this system, either by jamming or actively spoofing the GNSS signals.
Jam Warfare
GNSS spoofing illustrated. (Credit: C4ADS)
The concept of jamming radio frequency communications is quite straight-forward: simply broadcast on the frequencies you wish to jam with more power than the original transmitter is capable of. Since the GNSS signal is relatively faint, this makes it easy for a ground-based system to jam this signal. Of course, since loss of a GNSS satellite fix is a known issue, backup strategies for this scenario are common, and it's also very noticeable due to the loss of communication from a satellite.
Spoofing is a lot more subtle than jamming, as well as more versatile. Instead of merely blasting the airwaves with raw power, GNSS spoofing still involves overpowering the original signal, but instead of a denial of service (DoS) attack, spoofing is closer to a man-in-the-middle (MitM) attack, where fake satellite signals are presented to the receiver as being the genuine signals, with of course spoofed parameters that will cause the receiver to calculate a position that's far away from where it actually is.
In a 2019 report by C4ADS (Center for Advanced Defense Studies) titled Above Us Only Stars - Exposing GPS spoofing in Russia and Syria, a number of observations are reported on where Russia has used GNSS spoofing, for a variety of reasons. An interesting and common use appears to be the spoofing of GNSS signals so that receivers think that they are located at a nearby airport. Presumably this would trigger the geofencing limitations in drones and similar, which would then refuse to take off. This could be useful during VIP visits as an anti-drone strategy, for example.
Less harmless is the military use, where during recent Russian and NATO exercises Norway and Finland reported severe GPS outages. This affected the public by limiting the navigation capacity of commercial airliners, and also disrupted the use of cellphone networks. Supposedly, in 2011 Iran used GPS spoofing to trick a Lockheed Martin RQ-170 drone to land on one of its airfields, where it was subsequently captured. Similarly, there have been multiple occasions now where marine traffic has been disrupted due to faulty GPS data being fed to the automatic identification system (AIS).
As the 2019 C4ADS report notes, this has been reported by ships in the Black Sea on multiple occasions, and also in 2019 it was reported that an American container ship - the MV Manukai - noticed very strange behavior while at the port in Shanghai, China. According to its AIS screen, one ship was shown as moving in the same channel as the Manukai , before vanishing from the screen, then appearing at the dock, before appearing in the channel and so on. When the mystified captain picked up the binoculars and scanned for this ship, it was clearly stationary at the dock that entire time.
GNSS Hunting
GPS interference can be pinpointed based on this ring of false AIS positions. Approximately 200 meters in diameter, many of the positions in the ring had reported speeds near 31 knots (much faster than a normal vessel speed) and a course going counterclockwise around the circle. AIS data courtesy Global Fishing Watch / Orbcomm / Spire.
What's mystifying about the GNSS spoofing as detected in Shanghai is that instead of it merely moving the calculated position to a nearby fixed point, what we see when we collate the wrong AIS data onto a map is that they form near-perfect circles. This is noted by both the MIT Technology Review article, as well as a later article by SkyTruth.
What is interesting is that when using the anonymized route information from Strava in Shanghai, this same 'circle spoofing' could be observed, independent from the AIS information. Somehow it would seem that the spoofed data is constantly updated, to make it appear that the affected receiver is in motion, and travelling in this large circle.
Exactly how this is done, or why, is still unknown, with no major updates since the initial reporting in 2019. Whether the intent is to hide illicit activity, or whether it's due to some kind of cyberhacks or a glitch, nobody is entirely sure. Even independent from Iran, China and Russia, GPS-related location glitches keep happening.
Yet as a team from the University of Texas at Austin demonstrated in 2013 already using $2,000 worth of equipment and an $80 million yacht, spoofing GPS signals is relatively easy and straightforward. It doesn't take a lot of imagination to picture what is possible today, since since that demonstration nine years ago using a university-budget, especially when upgraded to a nation-sized budget.
According to current reports, Russia is actively spoofing GPS data during the war in Ukraine, which would affect mostly private and commercial users. Whether the US military has additional backups in the case of spoofing and jamming attempts is naturally unknown, due to national security reasons. Even so, with the importance of GNSS today with navigation and so much more, it would seem pertinent to wonder whether spoofing can be detected or circumvented.
Knowing Is Half The Battle
In an [analysis by Guy Buesnel](https://galileognss.eu/with-gnss-spoofing-attacks-on-the-rise-resilience-and-robustness-go-hand-in-hand/#more-3805), he notes that there are quite a few risks in the GNSS chain, not the least of which is faulty equipment, and sources of interference. Perhaps the most important lesson of the past years has been that solely relying on GNSS is risky, and that adding additional ways to determine one's position is essential, as well as the ability to detect the act of spoofing.
This aspect of detecting and possibly circumventing spoofing is currently the topic of active research, as noted by e.g. [Mark L. Psiaki, et al.](https://galileognss.eu/with-gnss-spoofing-attacks-on-the-rise-resilience-and-robustness-go-hand-in-hand/#more-3805) in a recent paper. While there's unlikely to be a silver bullet that will fix all ills and return GNSS to the infallible system that was promised to us by glossy flyers years ago, what we are likely to see the coming time are better, more robust GNSS receivers. We're already seeing that GNSS receivers built into smartphones can use multiple GNSS constellations, with the ability to use local WiFi networks and so on as augmentation.
Using fairly low-tech improvements it would be easy to detect many spoofing attacks, such as when one's calculated location suddenly and dramatically changes, or when one's calculated course does not match with the data provided by the augmentation system, cell towers, or other sources of location information.
Even if GNSS isn't the effortless panacea that many had assumed it to be, it is still a major navigational marvel, and a cornerstone of modern civilization that will continue to see improvements as it has since the first GPS satellite was launched. It just takes staying one step ahead of the meddling hackers.
#currentevents #gpshacks #originalart #gnss #gnssspoofing #gps
Low Power Mode for Custom GPS Tracker
GPS has been a game-changing technology for all kinds of areas. Shipping, navigation, and even synchronization of clocks have become tremendously easier thanks to GPS. As a result of its widespread use, the cost of components is also low enough that almost anyone can build their own GPS device, and [Akio Sato] has taken this to the extreme with efforts to build a GPS tracker that uses the tiniest amount of power.
This GPS tracker is just the first part of this build, known as the air station. It uses a few tricks in order to get up to 30 days of use out of a single coin cell battery. First, it is extremely small and uses a minimum of components. Second, it uses LoRa, a low-power radio networking method, to communicate its location to the second part of this build, the ground station. The air station grabs GPS information and sends it over LoRa networks to the ground station which means it doesn't need a cellular connection to operate, and everything is bundled together in a waterproof, shock-resistant durable case.
[Akio Sato] imagines this unit would be particularly useful for recovering drones or other small aircraft that can easily get themselves lost. He's started a crowdfunding page for it as well. With such a long battery life, it's almost certain that the operator could recover their vessel before the batteries run out of energy. It could also be put to use tracking things that have a tendency to get stolen.
#gpshacks #airstation #durable #energy #gps #groundstation #lora #power #small #tracker
Vacuum “Tube” Might Replace GPS One Day
GPS and similar satellite navigation systems changed everything. The modern generation is far less likely to have had to fold a service station map or ask someone for directions on the side of the road. But GPS isn't perfect. You need to see the sky, for one thing. For another, an adversary could jam or take down your satellites. Even a natural disaster could temporarily or permanently knock out your access to the satellites.
The people at Sandia National Labs worry about things like that and they want to replace GPS with quantum accelerometers and gyroscopes. The problem: those things take expensive and bulky vacuum systems and lasers. Sandia, however, has had a sealed device about the size of an avocado that weighs about a pound that could possibly do the job. Their goal is to see it work without maintenance for four more years.
This is no ordinary vacuum tube, though. It is made of titanium and sapphire. By itself, the device doesn't do much of anything, but it shows that rubidium can be contained in a sealed chamber with no additional pumping. These quantum sensors aren't anything new, but a tiny self-contained cold-atom sensor can pave the way for putting these sensors in vehicles like ships, aircraft, and ground vehicles. Submarines, which don't usually have a clear shot at the sky without floating an antenna, are also candidates for the new technology.
A navigation system based on this technology uses a laser to cool the subject atoms and then measures their movements. This allows very precise determination of acceleration and rotation which allows for a more precise inertial navigation system.
If you need a refresher on how GPS works, we can explain it. If you think the idea of a module containing rubidium is far-fetched, don't forget you can already get them for precision clock work.
#gpshacks #science #gps #quantumaccelerometer #quantumgps #quantumgyroscope #quantumnavigation #rubidium #sandianationallaboratory
Gladys West Modelled the Earth So That We Can Have GPS
The name Gladys West is probably unfamiliar, but she was part of creating something you probably use often enough: GPS. You wouldn't think a child who grew up on a sharecropping farm would wind up as an influential mathematician, but perhaps watching her father work very hard for very little and her mother working for a tobacco company made her realize that she wanted more for herself. Early on, she decided that education was the way out. She made it all the way to the Naval Surface Warfare Center.
While she was there she changed the world with -- no kidding -- mathematics. While she didn't single-handedly invent satellite navigation, her work was critical to the systems we take for granted today.
Flying High
West had a passion for satellite altimeters. We think of a satellite being a certain height over the surface of the Earth, but that's not really accurate. The Earth's surface isn't a smooth ball. Passing over a hill or a valley means that the exact distance from the surface to the satellite changes almost constantly. Passing over water is another problem. If you want to be precise, all these things matter. And if you want to build a Global Positioning System, you want to be precise.
West modeled the Earth's exact shape based on data from the GEOS satellite. She later became the project manager for SEASAT, which used radar to measure the ocean surface. Her interest led her to work with the IBM 7030 computer to refine models of the Earth known as the geoid. This takes into account things like tidal forces and gravity to compute the true shape of the Earth, rather than simply assuming that it's a perfect sphere. An accurate geoid is an important part of today's GPS and similar navigations systems.
Full Ride
Her family did not have the money to send West to school, so she worked hard to earn a full scholarship. The top two graduating high school students got a full ride and through discipline and her intellect, graduated valedictorian in 1948.
She was excellent in all her subjects but elected to major in math. After a brief tenure teaching, she went back for a Master's degree. Even with an advanced degree, though, teaching didn't pay very well. Despite her trepidation in moving to Virginia during the 1960s, the Navy job offered her a better wage and she stayed in that job until retirement over four decades later.
Legacy
West received several awards during her time at work. In addition, she was inducted into the Air Force Hall of Fame in 2018. The Navy even produced a short video that you can see below.
Of course, many people worked on GPS -- known as NAVSTAR at its inception. It wasn't even the first system of its kind. That honor probably goes to the 1960 Transit project. But all of these systems needed accurate mathematical models of the Earth, and West was a key part of the team that made that happen. Making accurate clocks, keeping them in sync, and shrinking all the components down with a low cost have their own stories and heroes, but for the math, we can thank Gladys West.
We like knowing the stories behind the tech we use every day. We think Gladys West is even more inspiring because of her humble beginnings and the obvious determination and intellect she had to carry her so far. Gladys got her PhD after she retired, but we understand she still prefers to use paper maps.
Want to know more about GPS? We can help. Just want to use it? We've come a long way from $3,000 handheld GPS units.
#biography #featured #gpshacks #originalart #geoid #gps #measurement #navy #satellitenavigation
Keep An Eye On Your Bike With This DIY GPS Tracker
Owning a bike and commuting on it regularly is a great way to end up with your bike getting stolen, unfortunately. It can be a frustrating experience, and it can be particularly difficult to track a bike down once it's vanished. [Johan] didn't want to be caught out, however, and thus built a compact GPS tracker to give himself a fighting chance to hang on to his ride.
It's built around the Arduino MKR GSM, a special Arduino built specifically for Internet of Things project. Sporting a cellular modem onboard, it can communicate with GSM and 3G networks out of the box. It's paired with the MKR GPS shield to determine the bike's location, and a ADXL345 3-axis accelerometer to detect movement. When unauthorised movement is detected, the tracker can send out text messages via cellular connection in order to help the owner track down the missing bike.
The tracker goes for a stealth installation, giving up the deterrent factor in order to lessen the chance of a thief damaging or disabling the hardware. It's a project that should give [Johan] some peace of mind, though of course knowing where the bike is, and getting it back, are two different things entirely. We've seen creative techniques to build trackers for cats, too. It used to be the case that such "tracking devices" were the preserve of movies alone, but no longer. If you've got your own build, be sure to let us know on the tipline!
#gpshacks #bicycle #bike #gps #gpstracker #tracker #trackingdevice
Open Source Pizza Compass Will Show You the Way
In Pirates of the Caribbean , Captain Jack Sparrow has an enchanted compass that points to what the holder wants most in life. The Pizza Compass created by [Joe Grand] is basically the same thing, except it's powered by a Particle Boron instead of a voodoo spell. Though depending on who's holding the thing, we imagine they'd even point in the same direction.
[Joe] was tasked by Wired to design and produce the Pizza Compass in three weeks, a process which was documented in the video below. Being the Badgelife luminary that he is, the final product looks far more attractive than it has any business being. In addition to the Particle Boron that slots in on the back of the handheld PCB, there's a GlobalTop PA6H GPS module, a LSM303DLHC compass, and eight NeoPixels that correspond to the points on the silkscreen compass.
From prototype to final product.
Using the device is simple, just press the button and then walk around trying to keep the top-most LED lit. Behind the scenes, the Boron is pulling down the coordinates of the closest pizza place as reported by Google's API, and comparing that to the user's current GPS location. In practice that means the Pizza Compass isn't concerned with nuances like streets or buildings, so its up to the user to figure out how best to stay on the desired heading. So rather than just following some turn-by-turn directions, there's some proper navigation involved if you want that fresh slice.
If you don't like pizza, you could reprogram the compass to point to whatever quest-worthy resource you wish. As explained at the end of the video, [Joe] wanted this to be an open source project so it could easily be adapted for different tasks by the community. Though honestly, it's pretty weird if you don't like pizza.
We've actually covered a very similar device in the past that would point the user to the closest White Castle or Five Guys, but with all due respect to that project, the Pizza Compass is in another league. When you've got the talent and experience of [Joe Grand] on the team, even the most mundane of gadgets ends up looking like a piece of art.
#gpshacks #ledhacks #compass #geolocation #gps #joegrand #rgbled
Client Info
Server: https://mastodon.social
Version: 2025.04
Repository: https://github.com/cyevgeniy/lmst