6 ms·

Japan's Plan for Centimeter-Resolution GPS

114 points by JamilD 12y ago

dfc 12y ago
GPS is a misnomer, it should be JPS, Japan Positioning System, nothing global to see here folks. It is unfortunate that the article does not stress that this system is only useful in Japan; especially with the conclusion that many nations will be watching the results given the "range of promised applications [range of use, certainly not geographic range] and relatively low cost." That being said I am interested to see how the experiment with atomic clockless birds goes. One of the most overlooked features of GPS is time transfer.
- MrUnderhill 12y ago
  Well, only sort of: GPS is the initialism for a specific system (and QZSS provides corrections for that particular system's satellites, among other things), not a generic term for global navigation satellite systems. Had it said "Japan’s Plan for Centimeter-Resolution GNSS", it would have been different. Europe has EGNOS, which is similar (and was recently granted €1.3 billion for upgrades), the US has WAAS, and India has something similar too [1][2]. [1] http://en.wikipedia.org/wiki/Indian_Regional_Navigational_Satellite_System http://en.wikipedia.org/wiki/Indian_Regional_Navigational_Sa... [2] http://en.wikipedia.org/wiki/GAGAN http://en.wikipedia.org/wiki/GAGAN
  - swatkat 12y ago
    Yes. India has GAGAN (GPS Aided Geo-Augmented Navigation)[1][2] to augment GPS accuracy, similar to EGNOS and WAAS. Apart from this, there's IRNSS (Indian Regional Navigational Satellite System)[3], which is an indigenous satellite navigation system independent of GPS. [1]http://gpsworld.com/gagan-certified-for-aviation-in-india/ http://gpsworld.com/gagan-certified-for-aviation-in-india/ [2]http://www.isro.org/pressrelease/scripts/pressreleasein.aspx?Jan03_2014 http://www.isro.org/pressrelease/scripts/pressreleasein.aspx... [3]http://en.wikipedia.org/wiki/Indian_Regional_Navigational_Satellite_System http://en.wikipedia.org/wiki/Indian_Regional_Navigational_Sa...
  - dfc 12y ago
    "Well only sort of" what? Yes, "GPS is the initialism for a specific system" and G is the initial for Global. The G in GNSS is also global so I am not sure how that is any different. The article is titled "Japan's Plan for Centimeter-Resolution GPS" and then goes on to describe a system that is anything but global.
    - swatkat 12y ago
      GNSS is a generic term for globally available satellite navigation system. GPS is a GNSS implemented and maintained by the USA. Japan is planning to launch thier own satellites as part of QZSS program, to augment this GPS coverage over Japan. GPS receivers in Japan can make use of these "local" sats along with American sats for more accurate positioning.
      - dfc 12y ago
        This system is not globally available.
ersii 12y ago
I'm having trouble understanding the practical consequences of this project. If I would be in Japan, with a regular, GPS-tuned/understanding device, would I get better service? Or would I need a special device, that'd be able to understand GPS+"JPS"? The part where they transmit correction data to the satellites also confuse me, if that's what they're doing; It's not the same as the United States Global Positioning Service if that'd be the case, right? For what I've understood, the GPS doesn't need a constant feeding of data from ground stations - it's ""simply"" a bunch of satellites sending out the current time from their on-board atomic clocks.
- dfc 12y ago
  > GPS doesn't need a constant feeding of data from ground stations This is not the case. USNO steers the clocks(4x) on the satellites. I think they do this via the AF but I have always been a little uncertain of the exact method: GPS time is automatically steered to UTC(USNO) on a daily basis to keep system time within one microsecond of UTC(USNO) modulo 1 second, but during the last several years has been within a few hundred nanoseconds. The rate of steer being applied is +/-1.0E-19 seconds per second squared.[^1] One of the reasons for JPS's need for direct contact with ground stations is that the newer satellites do not contain the any rubidium frequency standards and use an experimental time synching system. [^1]: http://tycho.usno.navy.mil/gpstt.html http://tycho.usno.navy.mil/gpstt.html
  - icegreentea 12y ago
    GPS ground updates correct for clock skew and disturbances in orbits. The Japanese system also seems to upload the differential measurements of their entire ground reference points to rebroadcast to individual receivers. In some senses, the technique is just an augmentation/expansion of WAAS [0] to Japan (WAAS is strictly North American). [0] http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System EDIT: And to the OP, you would need some sort of GPS+ device.
  - rasz_pl 12y ago
    W T F??? Why wouldnt they include rubidion clock on sats? Its at most $10K expense on something costing tens of millions to launch. Does this mean GPS will stop working when Zombies/Pandemic/whatever strikes and wipes out US military?
gorloth 12y ago
This seems to be similar to the usage of WAAS in the US (http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System), just on a smaller geographic scale. One of the bigger sources of error in GPS today is due to various atmospheric effects that bend the signal and increase the signals propagation delay. A ground stations in a known position can generate correction for the errors but the farther it's from the ground station the less useful the correction is. I've seen GPS systems used in farming applications that use a local tower that can provide corrections to give a very accurate position for the local area.
- kbaker 12y ago
  It does seem like WAAS at first glance, but I actually think they are creating their own GPS-compatible satellites: > To put it simply, with QZSS it is like the number of GPS satellites has been increased. Because QZSS has interoperability with GPS, the number of satellites that can transmit satellite signals at the same time is increased, which makes stable positioning possible. This also decreases the positioning errors as described. [1] With L1 and L5 carriers on GPS now, you can definitely get down to cm-level positioning already. I think they are just launching more satellites in Japan-specific orbits so they have better, faster GPS coverage above Japan, and especially in dense cities where you need a high angle of elevation for positioning satellites. The farming systems are more real-time kinematic GPS, which broadcast local corrections from a dedicated reference statiion. [2] [1] http://www.qzs.jp/en/services/index.html http://www.qzs.jp/en/services/index.html [2] http://en.wikipedia.org/wiki/Real_Time_Kinematic http://en.wikipedia.org/wiki/Real_Time_Kinematic
- ghshephard 12y ago
  Back in 1995 I wrote the mapping software for a "Tundra Tracker", this was the navigation software for a supply vehicle that could navigate in the arctic in whiteout conditions. The idea was to have someone drive a path while conditions were good, and we would then lock in all the waypoints. Rather than store all the waypoints for the path, we were able to eliminate about 99% of them with various splining algorithms. One of our big concerns back then, though, was that US Military would degrade the SA (Selective Availability) signal - it had happened in the Gulf War, and our tracks, which were normally accurate to within 3-4 meters, went wacky and were almost 50 meters off at times. The solution was to mount a radio antenna, have it calculate it's "True" location by averaging a couple days worth of GPS signals, and then, continually transmit the difference between a current GPS signal and it's known location. This Differential GPS let us calculate paths to within 1m of accuracy. When I asked what prevented a military opponent from doing the same thing, I was told that the first thing in the battlefield that gets hit as a command center would be anything transmitting RF, particularly if it was believed to be for D-GPS. Also, D-GPS isn't that effective for missile tracking, as you need to get differential signals in areas outside of your zone of control.
vdm 12y ago
http://en.wikipedia.org/wiki/GNSS_augmentation http://en.wikipedia.org/wiki/GNSS_augmentation
dalek2point3 12y ago
Very interesting. Actually, something similar happened in the US back in 2000, when Clinton turned off something called "Selective Availability" in the US. This program deliberately degraded civilian GPS signals. After SA was turned off, we went from a GPS system that was accurate to a football field-type area to one that is accurate to a tennis-court ish area. Read more: http://www.gps.gov/systems/gps/modernization/sa/ http://www.gps.gov/systems/gps/modernization/sa/
- mkempe 12y ago
  I don't understand these units of measurement. Football-field GPS was 4 times less accurate than tennis-field GPS? your reference indicates that uncertainty was 45 meters and became 6.5 meters, one order of magnitude improvement. To continue with mixed standards -- a tennis court measures 23.78 by 10.97 meters (78 by 36 feet, I'm surprised it hasn't been metrified). The Japanese system should be about 3 orders of magnitude more precise than tennis-court-rated GPS.
  - jws 12y ago
    Wolfram Alpha says: area of an NFL football field in square meters: 5351m^2 area of a circle of radius 45 meters: 6361.73m^2 area of a tennis singles court in square meters: 196.7m^2 area of a circle of radius 6.5 meters: 133m^2 It's pretty close. (A volleyball court would be closer at 162m^2.)
  - yaix 12y ago
    So, table tennis table? Chess board?
- dfc 12y ago
  This is nothing like turning SA off. SA was the intentional injection of pseudorandom data to degrade GPS accuracy in order to deny enemies accurate positioning data. This is a system of satellites launched to augment GPS signals in a certain area of the globe for advanced civilian positioning applications.
jccooper 12y ago
If anyone's wondering about the orbit, it's a geosynchronous but not geostationary orbit. The geosynchronous part is so that they only need a few sats to cover their region, unlike GPS which is global and requires some 32 sats. It's not an equatorial geostationary orbit so that receivers at higher latitudes (in Japan) will see a sat overhead instead of always over the equator. This is to deal with the "canyon" effect. Guaranteeing a bird overhead, rather than GPS's catch-as-catch-can, should definitely help signal reliability. These will be further away than GPS, which are medium Earth orbit. Some other info (including an animation) here: http://global.jaxa.jp/countdown/f18/overview/orbit_e.html http://global.jaxa.jp/countdown/f18/overview/orbit_e.html It should also be useful in Australia and parts between. They will also park spare sats in geostationary equatorial orbits. It's a bit inspired, I think, by the Molniya orbit, another technique to get long-duration high-latitude overflight: http://en.wikipedia.org/wiki/Molniya_orbit http://en.wikipedia.org/wiki/Molniya_orbit
- dfc 12y ago
  Another neat thing about the orbit, Pine Gap[^1] sits right in the middle of the bottom half of the figure eight. As far as "should be useful" goes do you know if Japan has ground stations in Australia? [^1]: https://en.wikipedia.org/wiki/Pine_Gap https://en.wikipedia.org/wiki/Pine_Gap
  - jccooper 12y ago
    There's one in Canberra, as well as Guam, Hawaii, and Bangalore. I don't know if they're Japanese per se; "joint" is probably better. The US territory ones are NOAA or NASA in collaboration with JAXA. http://www.insidegnss.com/auto/popupimage/QZSS%20ground%20segment_lo.jpg http://www.insidegnss.com/auto/popupimage/QZSS%20ground%20se... Dunno if those will help with the "centimeter resolution" bit, but it'll certainly augment GPS. The dwell over Australia and other non-Japan areas for the non-stationary sats will be shorter, but still will be useful while they are visible. And outside of "canyon" areas that will be quite often. The geostationary sats will be useful over quite a lot of the west Pacific and east Indian oceans.
- TorKlingberg 12y ago
joushx 12y ago
What a wonderful example for the "standards" xkcd: https://xkcd.com/927/ https://xkcd.com/927/ Many countries in these days try to build their own alternative to GPS, or in this example a extension for it. This for sure makes the location mor accurate and the systems are independant from the united states. On the other hand for instance mobile phones have to implement all these systems and this makes them much more expensive and complicated. From my point of view it would be better to build up a universal international system. Yes, and I know this is nearly undoable.
- cyanoacry 12y ago
  In this case, Japan's move makes sense. The satellites are placed into an orbit so that they can be seen high in the sky, which is impossible to do for all locations on the earth. At some point, you need to break up the augmentation systems on a continent/country-wide basis so that you can optimize the satellite orbits to work for you, instead of against you. Additionally, QZSS seems to be pretty similar to WAAS. I get the feeling it's probably the same sort of system (though I haven't taken a look), so it's likely easy to implement from a GPS chip perspective.
- dfc 12y ago
  This has nothing to do with that XKCD comic. Did you read the article? This system is not "independent of the US," it augments the GPS system.
  - joushx 12y ago
    Yes. Did you read my comment? "[...], or in this example a extension for it"
deleted 12y ago
[deleted]
bitL 12y ago
I hope they are going to improve precision of elevation as well, not just longitude and latitude.
- GregorStocks 12y ago
  The article says it has 2.9 centimeter vertical resolution.
pixelcort 12y ago
Having moved to Tokyo last year, I'm really hopeful for more accurate altitude data. Much of Tokyo is under and above ground level, and I wish the altitude data were accurate enough to determine which floor I'm on. Perhaps Bluetooth LE and beacons will eventually allow more accurate elevation info.
Rusky 12y ago
Wow, I didn't know GPS technology was even capable of that accuracy. It would be interesting to see it used in augmented reality as well as the examples from the article. You could actually have shared virtual objects positioned out in the world.
coldcode 12y ago
If you combined cm accuracy in cell phone tracking and a armed quadcopter, and hacked the phone company, you could build a handy remote killing device.

114 points by JamilD 12y ago

dfc 12y ago

GPS is a misnomer, it should be JPS, Japan Positioning System, nothing global to see here folks. It is unfortunate that the article does not stress that this system is only useful in Japan; especially with the conclusion that many nations will be watching the results given the "range of promised applications [range of use, certainly not geographic range] and relatively low cost." That being said I am interested to see how the experiment with atomic clockless birds goes. One of the most overlooked features of GPS is time transfer.

MrUnderhill 12y ago
Well, only sort of: GPS is the initialism for a specific system (and QZSS provides corrections for that particular system's satellites, among other things), not a generic term for global navigation satellite systems. Had it said "Japan’s Plan for Centimeter-Resolution GNSS", it would have been different. Europe has EGNOS, which is similar (and was recently granted €1.3 billion for upgrades), the US has WAAS, and India has something similar too [1][2]. [1] http://en.wikipedia.org/wiki/Indian_Regional_Navigational_Satellite_System http://en.wikipedia.org/wiki/Indian_Regional_Navigational_Sa... [2] http://en.wikipedia.org/wiki/GAGAN http://en.wikipedia.org/wiki/GAGAN
- swatkat 12y ago
  Yes. India has GAGAN (GPS Aided Geo-Augmented Navigation)[1][2] to augment GPS accuracy, similar to EGNOS and WAAS. Apart from this, there's IRNSS (Indian Regional Navigational Satellite System)[3], which is an indigenous satellite navigation system independent of GPS. [1]http://gpsworld.com/gagan-certified-for-aviation-in-india/ http://gpsworld.com/gagan-certified-for-aviation-in-india/ [2]http://www.isro.org/pressrelease/scripts/pressreleasein.aspx?Jan03_2014 http://www.isro.org/pressrelease/scripts/pressreleasein.aspx... [3]http://en.wikipedia.org/wiki/Indian_Regional_Navigational_Satellite_System http://en.wikipedia.org/wiki/Indian_Regional_Navigational_Sa...
- dfc 12y ago
  "Well only sort of" what? Yes, "GPS is the initialism for a specific system" and G is the initial for Global. The G in GNSS is also global so I am not sure how that is any different. The article is titled "Japan's Plan for Centimeter-Resolution GPS" and then goes on to describe a system that is anything but global.
  - swatkat 12y ago
    GNSS is a generic term for globally available satellite navigation system. GPS is a GNSS implemented and maintained by the USA. Japan is planning to launch thier own satellites as part of QZSS program, to augment this GPS coverage over Japan. GPS receivers in Japan can make use of these "local" sats along with American sats for more accurate positioning.
    - dfc 12y ago
      This system is not globally available.

ersii 12y ago

I'm having trouble understanding the practical consequences of this project. If I would be in Japan, with a regular, GPS-tuned/understanding device, would I get better service? Or would I need a special device, that'd be able to understand GPS+"JPS"? The part where they transmit correction data to the satellites also confuse me, if that's what they're doing; It's not the same as the United States Global Positioning Service if that'd be the case, right? For what I've understood, the GPS doesn't need a constant feeding of data from ground stations - it's ""simply"" a bunch of satellites sending out the current time from their on-board atomic clocks.

dfc 12y ago
> GPS doesn't need a constant feeding of data from ground stations This is not the case. USNO steers the clocks(4x) on the satellites. I think they do this via the AF but I have always been a little uncertain of the exact method: GPS time is automatically steered to UTC(USNO) on a daily basis to keep system time within one microsecond of UTC(USNO) modulo 1 second, but during the last several years has been within a few hundred nanoseconds. The rate of steer being applied is +/-1.0E-19 seconds per second squared.[^1] One of the reasons for JPS's need for direct contact with ground stations is that the newer satellites do not contain the any rubidium frequency standards and use an experimental time synching system. [^1]: http://tycho.usno.navy.mil/gpstt.html http://tycho.usno.navy.mil/gpstt.html
- icegreentea 12y ago
  GPS ground updates correct for clock skew and disturbances in orbits. The Japanese system also seems to upload the differential measurements of their entire ground reference points to rebroadcast to individual receivers. In some senses, the technique is just an augmentation/expansion of WAAS [0] to Japan (WAAS is strictly North American). [0] http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System EDIT: And to the OP, you would need some sort of GPS+ device.
- rasz_pl 12y ago
  W T F??? Why wouldnt they include rubidion clock on sats? Its at most $10K expense on something costing tens of millions to launch. Does this mean GPS will stop working when Zombies/Pandemic/whatever strikes and wipes out US military?

gorloth 12y ago

This seems to be similar to the usage of WAAS in the US (http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System), just on a smaller geographic scale. One of the bigger sources of error in GPS today is due to various atmospheric effects that bend the signal and increase the signals propagation delay. A ground stations in a known position can generate correction for the errors but the farther it's from the ground station the less useful the correction is. I've seen GPS systems used in farming applications that use a local tower that can provide corrections to give a very accurate position for the local area.

kbaker 12y ago
It does seem like WAAS at first glance, but I actually think they are creating their own GPS-compatible satellites: > To put it simply, with QZSS it is like the number of GPS satellites has been increased. Because QZSS has interoperability with GPS, the number of satellites that can transmit satellite signals at the same time is increased, which makes stable positioning possible. This also decreases the positioning errors as described. [1] With L1 and L5 carriers on GPS now, you can definitely get down to cm-level positioning already. I think they are just launching more satellites in Japan-specific orbits so they have better, faster GPS coverage above Japan, and especially in dense cities where you need a high angle of elevation for positioning satellites. The farming systems are more real-time kinematic GPS, which broadcast local corrections from a dedicated reference statiion. [2] [1] http://www.qzs.jp/en/services/index.html http://www.qzs.jp/en/services/index.html [2] http://en.wikipedia.org/wiki/Real_Time_Kinematic http://en.wikipedia.org/wiki/Real_Time_Kinematic
ghshephard 12y ago
Back in 1995 I wrote the mapping software for a "Tundra Tracker", this was the navigation software for a supply vehicle that could navigate in the arctic in whiteout conditions. The idea was to have someone drive a path while conditions were good, and we would then lock in all the waypoints. Rather than store all the waypoints for the path, we were able to eliminate about 99% of them with various splining algorithms. One of our big concerns back then, though, was that US Military would degrade the SA (Selective Availability) signal - it had happened in the Gulf War, and our tracks, which were normally accurate to within 3-4 meters, went wacky and were almost 50 meters off at times. The solution was to mount a radio antenna, have it calculate it's "True" location by averaging a couple days worth of GPS signals, and then, continually transmit the difference between a current GPS signal and it's known location. This Differential GPS let us calculate paths to within 1m of accuracy. When I asked what prevented a military opponent from doing the same thing, I was told that the first thing in the battlefield that gets hit as a command center would be anything transmitting RF, particularly if it was believed to be for D-GPS. Also, D-GPS isn't that effective for missile tracking, as you need to get differential signals in areas outside of your zone of control.

vdm 12y ago

http://en.wikipedia.org/wiki/GNSS_augmentation http://en.wikipedia.org/wiki/GNSS_augmentation

dalek2point3 12y ago

Very interesting. Actually, something similar happened in the US back in 2000, when Clinton turned off something called "Selective Availability" in the US. This program deliberately degraded civilian GPS signals. After SA was turned off, we went from a GPS system that was accurate to a football field-type area to one that is accurate to a tennis-court ish area. Read more: http://www.gps.gov/systems/gps/modernization/sa/ http://www.gps.gov/systems/gps/modernization/sa/

mkempe 12y ago
I don't understand these units of measurement. Football-field GPS was 4 times less accurate than tennis-field GPS? your reference indicates that uncertainty was 45 meters and became 6.5 meters, one order of magnitude improvement. To continue with mixed standards -- a tennis court measures 23.78 by 10.97 meters (78 by 36 feet, I'm surprised it hasn't been metrified). The Japanese system should be about 3 orders of magnitude more precise than tennis-court-rated GPS.
- jws 12y ago
  Wolfram Alpha says: area of an NFL football field in square meters: 5351m^2 area of a circle of radius 45 meters: 6361.73m^2 area of a tennis singles court in square meters: 196.7m^2 area of a circle of radius 6.5 meters: 133m^2 It's pretty close. (A volleyball court would be closer at 162m^2.)
- yaix 12y ago
  So, table tennis table? Chess board?
dfc 12y ago
This is nothing like turning SA off. SA was the intentional injection of pseudorandom data to degrade GPS accuracy in order to deny enemies accurate positioning data. This is a system of satellites launched to augment GPS signals in a certain area of the globe for advanced civilian positioning applications.

jccooper 12y ago

If anyone's wondering about the orbit, it's a geosynchronous but not geostationary orbit. The geosynchronous part is so that they only need a few sats to cover their region, unlike GPS which is global and requires some 32 sats. It's not an equatorial geostationary orbit so that receivers at higher latitudes (in Japan) will see a sat overhead instead of always over the equator. This is to deal with the "canyon" effect. Guaranteeing a bird overhead, rather than GPS's catch-as-catch-can, should definitely help signal reliability. These will be further away than GPS, which are medium Earth orbit. Some other info (including an animation) here: http://global.jaxa.jp/countdown/f18/overview/orbit_e.html http://global.jaxa.jp/countdown/f18/overview/orbit_e.html It should also be useful in Australia and parts between. They will also park spare sats in geostationary equatorial orbits. It's a bit inspired, I think, by the Molniya orbit, another technique to get long-duration high-latitude overflight: http://en.wikipedia.org/wiki/Molniya_orbit http://en.wikipedia.org/wiki/Molniya_orbit

dfc 12y ago
Another neat thing about the orbit, Pine Gap[^1] sits right in the middle of the bottom half of the figure eight. As far as "should be useful" goes do you know if Japan has ground stations in Australia? [^1]: https://en.wikipedia.org/wiki/Pine_Gap https://en.wikipedia.org/wiki/Pine_Gap
- jccooper 12y ago
  There's one in Canberra, as well as Guam, Hawaii, and Bangalore. I don't know if they're Japanese per se; "joint" is probably better. The US territory ones are NOAA or NASA in collaboration with JAXA. http://www.insidegnss.com/auto/popupimage/QZSS%20ground%20segment_lo.jpg http://www.insidegnss.com/auto/popupimage/QZSS%20ground%20se... Dunno if those will help with the "centimeter resolution" bit, but it'll certainly augment GPS. The dwell over Australia and other non-Japan areas for the non-stationary sats will be shorter, but still will be useful while they are visible. And outside of "canyon" areas that will be quite often. The geostationary sats will be useful over quite a lot of the west Pacific and east Indian oceans.
TorKlingberg 12y ago

joushx 12y ago

What a wonderful example for the "standards" xkcd: https://xkcd.com/927/ https://xkcd.com/927/ Many countries in these days try to build their own alternative to GPS, or in this example a extension for it. This for sure makes the location mor accurate and the systems are independant from the united states. On the other hand for instance mobile phones have to implement all these systems and this makes them much more expensive and complicated. From my point of view it would be better to build up a universal international system. Yes, and I know this is nearly undoable.

cyanoacry 12y ago
In this case, Japan's move makes sense. The satellites are placed into an orbit so that they can be seen high in the sky, which is impossible to do for all locations on the earth. At some point, you need to break up the augmentation systems on a continent/country-wide basis so that you can optimize the satellite orbits to work for you, instead of against you. Additionally, QZSS seems to be pretty similar to WAAS. I get the feeling it's probably the same sort of system (though I haven't taken a look), so it's likely easy to implement from a GPS chip perspective.
dfc 12y ago
This has nothing to do with that XKCD comic. Did you read the article? This system is not "independent of the US," it augments the GPS system.
- joushx 12y ago
  Yes. Did you read my comment? "[...], or in this example a extension for it"

deleted 12y ago

[deleted]

bitL 12y ago

I hope they are going to improve precision of elevation as well, not just longitude and latitude.

GregorStocks 12y ago
The article says it has 2.9 centimeter vertical resolution.

pixelcort 12y ago

Having moved to Tokyo last year, I'm really hopeful for more accurate altitude data. Much of Tokyo is under and above ground level, and I wish the altitude data were accurate enough to determine which floor I'm on. Perhaps Bluetooth LE and beacons will eventually allow more accurate elevation info.

Rusky 12y ago

Wow, I didn't know GPS technology was even capable of that accuracy. It would be interesting to see it used in augmented reality as well as the examples from the article. You could actually have shared virtual objects positioned out in the world.

coldcode 12y ago

If you combined cm accuracy in cell phone tracking and a armed quadcopter, and hacked the phone company, you could build a handy remote killing device.