Most phones are compatible with GPS(US) +Galileo(Europe)+Glonass(Russia). Most of them also report which constellation the locks are from. GPS status and toolbox on android is a fun way to see what you're connected to.
What we need, and will probably get soon, is inertial guidance based on laser ring or fibre optic gyros in mobiles. You get a location fix every week or so and it starts out much more accurate than gps.
The US system was first by maybe a decade or more so support is nearly universal. The other systems are largely copycat, purposely compatible with existing GPS receivers.
That's why it seems like we're relying on the US for GPS, they invented it and had a full constellation in orbit before anyone else even thought of it.
Of course we're on the internet which was also invented by the US govt so I'm not so surprised why "the backups for this backbone of the global economy have to be American" in reference to GPS at least
Corrections every week? This isn't possible given the drift rates of high end FOG or Lazer ring IMUs. A high-end marine-grade INS can cost over 1 million dollars. These systems will typically provide un-aided navigation solution drifts that are less than 1.8 km per day. This means that if the device were left stationary for one day, due to slight errors in the sensors and imperfect sensor calibrations, after integrating the position solution, the calculated position after one day would be 1800 meters away from the sensors actual position.
With ones that you can affordably put in a phone within minutes the drift will be huge. You need something to regularly correct for the drift and currently this is GPS.
From the abstract
> In 2006, we presented at DGON symposium in Stuttgart [2] the design and navigation results of MARINS, the first FOG-based navigation system within the class of 1 nautical mile per day. This navigation system in now in production...
> have we reached the limits of the technology or can we still improve the performance of our sensors?
> Of course, the present FOG design is not good enough for the required performance, even in a strictly controlled environment.
This is a discussion of how it could be improved not what is available in production and certainly not close to being available within a phone - which was the original point.
High end civilian IMU's typically use mechanical gyros which have been obsolete for decades. Also, a phone isn't typically moving constantly like the oceans so error rates would be lower.
Even if we could make that cheap and small enough it would still need regular corrections far more frequently than a week to be as good as a GPS is now.
Of course, that was the proposal. There's more datapoints if you're willing to get creative, wifi networks (already used for this), cooperative comparison with other mobile devices in a local meshnet, acoustic cues from the environment, machine analysis of captured images, etc. Obviously dead reckoning without gps is going to require a multi-pronged approach.
Please explain how this will work?
You don't think such a system is practical, or you don't think such a system is technologically feasible?
Or you just don't understand the system I'm describing?
If you really care you could sketch out what exactly it is and how it'd work for yourself for a couple of devices (or more) and see what issues you uncover.
If your acceleration sensor is off by 1 part per million, 9.8 m/s^2 (i.e. gravity) will turn into a positioning error of ~73km in one day.
And because of a long fly time or imprecise initial reference point (a submarine is floating) some do corrections. One of the coolest one for ICBMs is to use celestial navigation to correct errors. They'd have a window with a camera and would "look" for a few stars.
- GPS; widespread, low accuracy
- INS; always available, high short-term accuracy, terrible long-term accuracy
- terrain-matching: large-scale corrections.
The different characteristics allow one sensor to correct another to a degree to produce an overall stable position.
The system only went live in 2016. It's only been supported by Apple since the iPhone 6s, and Samsung has supported since the S8.
I would be hesitant to say that most phones are compatible. In 2016 most of the flagship phones had support but even having a compatible SoC doesn't mean it was implemented. The Google Pixel was released in 2016 with a Snapdragon 821 that is compatible yet the Pixel does not support Galileo.
Isn't this precisely how accelerometers/gyros in mobiles work?
For some reason I was convinced phone gyros use light interference in a spiral of optic fiber. Probably because I read about that design when I was looking how solid-state gyros in RC models work.
iPhone X specs list "GPS, GLONASS, Galileo, and QZSS" [1]. I'm pretty sure they've supported multiple GNSS systems for a few generations.
I know I've seen several GNSS modules from u-blox that support multiple GNSS systems as well. One example, NEO-M8, supports "BeiDou, Galileo, GLONASS, GPS / QZSS." [2]
I know I've also seen several cheap GPS modules that are GPS-only, so multiple GNSS support isn't ubiquitous, but it's probably ahead of IPv6 adoption.
Also eLORAN when?
"In GPS technology, the term "COCOM Limits" also refers to a limit placed on GPS tracking devices that disables tracking when the device calculates that it is moving faster than 1,000 knots (1,900 km/h; 1,200 mph) at an altitude higher than 18,000 m (59,000 ft).[2] This was intended to prevent the use of GPS in intercontinental ballistic missile-like applications.
Some manufacturers apply this limit only when both speed and altitude limits are reached, while other manufacturers disable tracking when either limit is reached. In the latter case, this causes some devices to refuse to operate in very high altitude balloons."
e.g. https://www.rtl-sdr.com/receiving-gps-with-an-rtl-sdr-dongle...
Every app on your phone cares about "Where am I now", but no app wants to know "Where was I 5 seconds ago, but with more accuracy than you knew when I last asked".
Neither android not iPhone have an API to allow GPS hardware to refine the accuracy of historic position locations.
Any sensitive Spectrum Analyser or SDR can see the bump in the spectrum caused by the GPS Signals. And quite a few amateurs have built homebrew GPS receivers.
Or they can buy a little GPS module and use the data stream for a huge range of projects.
Most modern digital Ham communication methods require a 10MHz feed from a GPS module to maintain sufficient time and frequency accuracy.
The limits are real, encoded in public law. I don't understand how you could possibly disagree with me on this point
The fact that you are enclosed in a faraday cage also isn't helping, but they make planes from plastic now, so this shouldn't always be the case.
The linked article that we're commenting on was about a software bug in GPS only
The root cause was a bug in the GPS network. When the U.S. Air Force, which operates the 31 satellites, decommissioned an older one and zeroed out its database values, it accidentally introduced tiny errors into the database, skewing the numbers
https://books.google.com/books?id=DuoKFiZKbwEC&pg=PA5&lpg=PA...
https://thenextweb.com/apple/2011/10/21/the-iphone-4s-glonas...
this is pretty old news.
I see GLONASS compatibility on "the specs" list of almost every smart phone on gsmarena[0]. Even iPhone 4S has it. Just did a quick look-up, newer phones now support GALILEO and BDS too.
Two other issues - the biggest one is mentioned in the article - global coverage. GLONASS is the only one to claim global coverage.
The other issue is that there's still a huge number of devices that don't support those systems. Most of the time if something says it uses/depends upon GPS, it means literally just that one system, not the others.
Where does the article say that?
I must apologize again for going a little off-topic
Very few. The Kremlin and the presidential palace in Damascus come to mind, but Russia is actively antagonizing the rest of the developed world, including the areas just outside the walls of those two.
And historically, I believe they have been allied with the Soviet Union whilst the USA has historically allied with their arch-rival Pakistan.
I'd go out on a limb and assert that if China disappeared tomorrow, the consequences to the world economy would be far more devastating. So much of the global economy is tied—directly or indirectly—to Chinese manufacturing. It would take multiple decades for the world to replace the supply chains and highly skilled labour.
Is the world dependent on the US? No, you're right that dependent is a very strong word. However, the US, for better or worse, provides a very high amount of global stability. The US has a massive economy and a very strong military, and the world would be very different if any country like that were to fail.
It depends on what you value, I guess.
"The products we do require really advanced tooling, and the precision that you have to have, the tooling and working with the materials that we do are state of the art. And the tooling skill is very deep here. In the US you could have a meeting of tooling engineers and I'm not sure we could fill the room. In China you could fill multiple football fields."
-- Tim Cook, from this article: https://www.inc.com/glenn-leibowitz/apple-ceo-tim-cook-this-...
https://en.wikipedia.org/wiki/GLONASS
https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)
https://en.wikipedia.org/wiki/BeiDou_Navigation_Satellite_Sy...
I do wonder how many of these are supported by common hardware like mobile phones, anybody have a pointer to a compatibility list? I know the Chinese government had been prodding its manufacturers to add BeiDou support pretty hard.