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.
All satellite nagivation systems are trivially jammable. They use DSSS to spread out codes and resist jamming but signal levels are still so weak at the surface it's trivial to block.
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
> 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.
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.
> 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.
Fibre optic gyros can be miniturized to millimeter dimension, if it wasn't for ITAR.
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.
This is drift for a "static" million dollar marine grade (i.e. highest grade we currently have) INS not in the ocean or moving. Drift is measured in non-moving conditions. These are the fiber optic and laser sytems you are referring to.
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.
You could use some smart heuristics to make corrections without a gps lock, like resetting the location to "home" if it is near enough and sits motionless over night, or making an adjustment whenever the location drifts too far from the known locations of currently connected cell towers.
You won't get close to GPS accuracy with these. The uncertainty from cell tower triangulation is huge (relatively). But yes, some kind of beacon that works like GPS on a local scale or detection of known mapped landmarks could be used for corrections but there are issues with these too. These could assist GPS location rather than replace it entirely.
> These could assist GPS location rather than replace it entirely.
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.
I could imagine a secure location service that allows your phone to compare its current expected position with other nearby phones' expectations of their positions. If it's over bluetooth or wifi, the positions should be within meters of each other. This could provide an input to a kalmann filter type position estimator to help reduce drift as you (for example) walk down the street.
I think there are both feasibility and practicality issues with the cooperative estimation scheme you are describing. Without already knowing where the phones are very accuratly there will be a lot of noise. Would need a lot more detail to really understand what you intend but first reaction is that it'd be very difficult to do well.
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.
You might be right but I have doubts. Most weapons are INS guided despite the long fly times of cruise missiles etc. ITAR has a massive chilling effect on development, I wouldn't be surprised if we had error rates of less than a meter a day in mobiles if development wasn't severely curtailed
This works the other way - you get to prove your assertion that inertial navigation could work with cheap miniaturized sensors. Anyone can cast a doubt without proof.
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.
Cruise missiles combine (using Tomahawk as an example) GPS, visual terrain-matching, radar terrain-matching, and INS. Because they know INS needs those constant corrections.
> Most weapons are INS guided despite the long fly times of cruise missiles etc.
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.
Cruise missiles are very different from (quasi-)ballistic or anti-aircraft missiles - they fly at subsonic speeds at low altitudes (usually using a turbojet) to avoid interception. For example, the classic Tomahawk flies at ~900km/h, with the long-range variants having a range of 2500km, giving a maximum flight time on the order of hours, and so a pure INS drift on the order of low hundreds of meters.
Not sure what IMUs you're using, but we've been using civilian MEMS and FOG IMUs for years now. You still can't make anything purely inertial good enough to keep position accurately enough to be a GPS replacement for more than a few hours.
So this is why my smartwatch can tell me my speed before it has a GPS lock, including indoors? Very cool! But of course, as you say, the reports of my absolute position are very inaccurate.
Velocity can come from dopplar shift of the GPS carrier frequencies. This is very accurate. An IMU can be used for walking speed estimation but it won't be as accurate using a human gait model or direct integration.
No, any position-solution produced before a GPS lock will be due to the approximation produced by either using the last-known position or the cell-tower triangulation.
That information is also used as a seed for the GPS lock to speed up the time-to-fix.
> Most phones are compatible with... Galileo(Europe)
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.
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.
> I do wonder how many of these are supported by common hardware like mobile phones, anybody have a pointer to a compatibility list?
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.
Any ill that would befall GPS could easily also affect those. The issue is "a shocking amount of critical infrastructure depends on positioning/timing information derived solely from a handful of satellites broadcasting weak signals in the 1.whatever GHz band", whoever runs the ground segment for these constellations is immaterial (to first order) and "GPS" is just layman terminology.
The real answer is star navigation at night and interial + sun guided during the day. Phone hardware is perfectly capable but ITAR says otherwise. There's a reason why every legal GPS receiver shuts down after altitude or speed limits are exceeded. Too easy to make weapons that fly in your window from hundreds of miles away, basically
From mynameisvlad link given below[1] the restrictions are to prevent intercontinental missile navigation not regular missile navigation. The official limits are a speed (1,000 knots) and an altitude (18,000 m), but many manufactures do an "or" test instead.
"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."
They don't need to. There is a great many of more cost-effective ways of causing havoc, and even if they really wanted to use GPS-guided missiles, it's probably a better bet to build slower missiles with consumer hardware, but build a lot of them - missile interceptors are very expensive. If a DIY $1k missile needs to be shot down by $1M Patriot, they'll be doing lots of damage with a couple of them, without even hitting anything.
That's not true at all. You can use a $20 SDR card to receive GPS signals and and then can decode them on any commodity laptop, or a small computer like a raspberry pi.
Receiving the signals is only a part of the problem, and even getting a "fix" isn't all that hard. Maintaining an accurate fix, and at the same time refining away previous errors, on a fast moving vehicle, is a dark art.
Software architectures are the limiting factor here.
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.
Possible maybe but unusual. 99% of ham is narrowband, GPS is spread across a megahertz. Somebody goofed and made a TV tuner chip that could be used as an SDR at that sample rate, and I'm sure the powers that be arent happy.
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.
Too late to edit so replying to myself. I was mostly wrong. The GPS limits are much higher than I thought, and accuracy of INS is too low, although I still think that limit is artificial.
The limits are higher altitude and faster speed then you've ever been. If the Concorde was around you would see it firsthand. Weapons would be worthless against first world defences at airliner height and speed. Gps receivers shut down on weather balloons regularly, it's a known issue
The limits are real, encoded in public law. I don't understand how you could possibly disagree with me on this point
The reason your GPS receiver does not work on a plane is likely because it's processing algorithms aren't tuned for those speeds. The popular Ublox NEO-6M for example needs to be explicitly switched to "airborne" mode.
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.
Unfortunately many cheap GPS chips use the (incorrect) or definition, not and. It was a pain to find one that works above 59000ft but very slow speed for a weather balloon project some years ago.
I like using a NSF funded mobile app "Flyover Country" [1] to identify features in the landscape when I fly. You can download the maps and data for you flight path a head of time and then use it in airplane mode on the plane. GPS works fine (by the window) and the app locates your position on the map.
> Any ill that would befall GPS could easily also affect those
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
GLONASS is supported in every major GPS-receiving chipset these days (including those in smartphones, etc), because Russia put a huge import tariff on any satellite navigation equipment that isn't GLONASS capable. So the manufacturers of such, who were already doing it, made GPS Rx chips that also listen to GLONASS.
Galileo is catching up too. There is a supported device list here: https://www.usegalileo.eu/EN/. In addition, Galileo was just added in a recent software update to some Garmin watches. (Interestingly, they have supported GLONASS for a while.)
> I do wonder how many of these are supported by common hardware like mobile phones, anybody have a pointer to a compatibility list?
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.
Others have already pointed out that these systems are also susceptible to the same types of jamming/interference.
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.
GPS satellites are in an unusual orbit (between LEO and geosynchronous) where there is not a lot of debris. They’re also highly redundant and the constellation can lose several satellites without dropping service. Jamming is honestly more of an issue than debris.
It focuses squarely on GPS and proposed American solutions to make GPS (only) more resilient, while ignoring the other three operational backups the world does have!
The article mentions all those systems by name. Of those, only GLONASS has global coverage (also mentioned in the article), and it is operated by a hostile state.
> There might be some areas in the world where Russia is apparently "not" a hostile state?
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.
HN is English-language, so it's a strong assumption that the majority of users are English speakers. Russia is to some extent hostile to all the major English-speaking nations (in large part because all of those nations are strongly allied).
Dependent is a strong word. If the USA disappeared tomorrow, the rest of the world would reorganise quickly enough; the global economy would settle into a new normal within a few years.
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.
It would not be normal in a few years. The US is also a very large manufacturer, much of which is in more "essential" goods such as large equipment. Individuals and governments across the world hold US treasuries, so the US disappearing would wipe out trillions of dollars of assets. The US currency is a common reserve currency across the world, and would become worthless, creating a massive domino effect in banking across the world. Many important internet services would no longer function. Countries like Japan and Israel which rely on the US for defense would suddenly face a decrease quality of life and even existential threats. The countries which rely on US aid would suffer greatly.
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.
While losing China would certain set off shockwaves, I'd say you are in fact on a limb and have it backwards. Manufacturing can be moved and trivially ramped over a few years, perhaps at great cost, but still, only cost. Advanced technology, culture, and other elite exports are not so easily moved to Bangladesh or Vietnam. I'll go out on a limb and say losing Japan would be a bigger loss for the world than losing China due to this. Things I own that are made in China, or have parts made in China, are mostly owned for the cheaper price, not for any uniqueness. Japan and the USA export unique things which cannot be replaced by merely paying a higher price. Losing Google alone would set the world years back. Losing America would scramble world culture entirely (maybe for the better, you say, but that's a value judgement). Whereas China is so insular, the world would move on quickly.
"There's a confusion about China. The popular conception is that companies come to China because of low labor cost. I'm not sure what part of China they go to but the truth is China stopped being the low labor cost country many years ago. And that is not the reason to come to China from a supply point of view. The reason is because of the skill, and the quantity of skill in one location and the type of skill it is."
"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."
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.