Do you know what the IODC word in GPS data means? If so, great! If not, head over to see the 32nd of [Michel van Biezen’s] 100-part video series on GPS. You probably want to watch the other 31 videos before he gets too much further ahead of you, too. [Michel] reminds you of that professor you had in college who knows a whole lot about something. In fact, scanning his YouTube channel, he knows a lot about many topics ranging from optics, chemistry, kalman filters, and lots of electronics.
There is a dedicated playlist for the GPS videos dating back to 2016. So 32 videos in about six years. So you might have a little time to catch up. While the first video is pretty introductory as you might expect, by the time you get to video 7 the topics switch to things like the C/A code, BPSK, and gory details of all the frame data, including the IODC word.
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?
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.
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.
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.
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!
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.
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.