Slashdot Mirror
Ground-Based GPS Mimic Is Inch Perfect
holy_calamity writes "For several years the U.S. Air Force has used WiFi-router-sized boxes on a New Mexico missile range to create a GPS-like service to track munitions to the nearest inch. Now the Australian company behind the technology is rolling it out for civilians. One gold mine is already using the tech and specifications are being released so that GPS receiver manufacturers can adopt the technology. Locata hopes that construction sites, factories and city governments will all want to install their own high accuracy 'location hotspots.'"
You'll need to unplug the router and plug it back in first.
Wasn't this like a system they used before GPS that was still in minimal use until recently?
I vaguely remember they still had PDP-8's still in storage as replacement parts
When people ask if I'm an optimist, I say "I hope so". --Bill Bailey
I wonder how long it will take before this becomes available for use in cellphones to improve the accuracy of tracking. It would make services like 'find my iphone' even better, but would also enable government agencies and stalkers to get an even better lock on those they're tracking.
TFA doesn't go into details, but I'm imagining a replacement for mo-cap and wiimote/kinect if it updates quickly enough, is small enough, and cheap.
Something tells me that an Australian company would not be using inches to track anything. TFA seems to agree. Our official conversion tables between metric and "ye olde worlde" include the phrase "an inch is as good as a mile", which does not bode well for its accuracy.
smaller and cheaper allowing rapid temporary deployment for project sites?
I have something in common with Stephen Hawking...
DGPS is all about using the fact that error in a normal satellite GPS signal is relatively constant in one location on Earth - the ground based transmitters just tell the DGPS receiver what that error is in your specific location. This sounds like they are using actual ground-based GPS transmitters, thereby removing the calculation of where the satellite is in the first place, to improve accuracy.
Doesn't the military use metric (klicks = km), along with every other industry that needs a sane measurement system?
I'm not a lawyer, but I play one on the Internet. Blog
AFAIK DGPS uses fixed nodes to broadcast error in the satellite signal, while this system used fixed nodes to act like satellites. So this system can work with zero signal from satellite.
with WiFi APs/Cell Towers/MAC addresses.
This could be used underground.
There are several solutions available currently that offer 1" or better absolute accuracy off of GPS signals. They all function by resolving the issue that GPS is precise, but not accurate. By positioning themselves at a known position in space, they calculate the offset from what GPS is telling them, and broadcast that to the nearby area. They end up being much cheaper as all you need is a good GPS receiver.
This solution instead requires accurate local time references, and as such is going to be considerably more expensive. The advantage of this system is that GPS has an incredibly weak signal. It requires line-of-sight, and even trees will block a signal. If inside a building, or down in a quarry, you are likely to not receive enough signals to get an accurate position lock. This uses local transmitters at high power to allow them to operate in less advantageous terrain.
No. Differential GPS uses a local transmitter to provide local offset to the GPS position. This uses local transmitters as the time source, to allow it to operate in places the GPS signals will not reach.
Such as ... in a gold mine.
Can anyone name any other technologies that were originally developed by the military which are in common use by private citizens today?
Millimeter accuracy in 3 dimensions would open up a lot of possibilities for use in robotics.
Is this the sort of technology used in those (Tokyo) Disney rides, like Pooh's Hunny Hunt and some water-based one? Every ride seemed to be different, and the cart would just go and do its own thing.
You mean aside from being completely different?
Now we just need to get our enemies to buy a whole bunch of these, and conveniently place them on all the nice targets we'd like to bomb.
-mrxak
Onions Will Kill You
GPS accuracy is poor to non-existent within buildings and underground. Accurate sensor localisation is far from trivial in such environments. One hurdle is multi-path interference which renders the time-to-receive of a packet as near useless. AFAIK to achieve a high level of accuracy requires a mesh-like network and the use of multiple sensors including accelerometers with the accuracy increasing with the number of nodes in the mesh.
The CSIRO, Australia's peak science body is has been working on wireless tracking for a while. Don't know if they are involved with this new company Locata or not.
There's a few companies doing Loran/GPS-like tracking of police radio transmissions based on time of signal receipt time at various antennae. Accuracy varies with precision of time signal, availability of multiple receivers, etc.
What is new here?
Complete lack of dependency upon satellite signals?
WWV time is almost everywhere, and free. A WWV receiver is a simple circuit.
If the only way you can accept an assertion is by faith, then you are conceding that it can't be taken on its own merits
Just need to shrink 'em to keyring size and I'll be able to find my keys! ;)
Those days have passed. Differential GPS DGPS comes close to the accuracy of this system. It was developed decades ago to circumvent the selective availability (SA) that the military hoped would limit civilian GPS accuracy. Nothing was ever done to stop DGPS implementations, so its doubtful the NSA or anyone else would try stepping in now.
Have gnu, will travel.
Differential GPS is much different than this system.
This system requires no component of GPS except a similar receiver. That way they can use it in places no satellite signal reaches...like mines and shielded research facilities.
If the only way you can accept an assertion is by faith, then you are conceding that it can't be taken on its own merits
That doesn't help where you can't get GPS - which is what this thing is for in the first place! It's for indoors, undergound etc.
No it doesn't. If the article gave you that incorrect impression there is another on the website of Australia's ABC Science Show from a program several months ago.
Such as underground where GPS signals do not go!
This has existed for years, and heaps of companies use it. from rio tinto automation to fork lifts and kalmars for product tracking. Sigh its paid advertising - a press release/paid feature. http://www.symeo.com/English/Products/Position-Measurement/LPR-products-for-position-measurement.html http://www.ctscts.com.au/shop/view/2d/41 http://www.idt.com.au/Stories/WSJ_Rio_Tinto_Perth%26Jupiter_Systems.pdf http://www.riotinto.com/documents/ReviewIssue90Jun09_the_shape_of_things_to_come.pdf
Yes of course. National internet filtering (of whatever, for whatever reason) is a great ploy to sell to nerds.
Were that I say, pancakes?
so they reinvented 1950's tech
And also no requirement for the expensive accurate time sources that are in the satellites.
There is a transcipt of an interview about it here:
http://www.abc.net.au/rn/scienceshow/stories/2010/3058425.htm
It's not that at all and is news:
http://www.abc.net.au/rn/scienceshow/stories/2010/3058425.htm
That doesn't help where you can't get GPS - which is what this thing is for in the first place! It's for indoors, undergound etc.
No it doesn't. If the article gave you that incorrect impression there is another on the website of Australia's ABC Science Show from a program several months ago.
Such as underground where GPS signals do not go!
Because I get lost walking from oneside of the bomb shelter to the other all the time.
WWV, et al, work on HF, and are subject to significant propagation delays. You can get much better time from the GPS constellation (25 ns, pretty easily). To get into the inch/centimeter range, you need sub nanosecond accuracy.
"National Security is the chief cause of national insecurity." - Celine's First Law
I've worked in the DGPS industry for nearly a decade now, and I can tell you that this is not a new concept in any way. Firstly, it is true that there exist many free correction sources (e.g. WAAS in the US, EGNOS in Europe) which will allow a DGPS receiver to determine it's position to decimetre accuracy. Centimetre accuracy can be achieved with Real Time Kinematic (RTK) corrections (either from a local base station or delivered remotely by some kind of long distance connection, e.g. GPRS). Neither option is free, but subscribing to a correction provider is a hell of a lot cheaper than buying your own base station. Millimetre accuracy can be achieved using very expensive laser equipment and is very common in the surveying industry.
The concept of using local transmitters for underground applications is not new either. I am aware of a number of mine sites in Australia which have been using Pseudolites (Pseudo Satellites) for a number of years for this exact purpose.
--- "When you're strange"
Are there any free DGPS data providers? Difficult to integrate into mobile platforms like Android? I spoke with the developer of GPS Status for Android and we were discussing WAAS integration, but apparently not enough of the low-level GPS system is available to android apps.
From TFA: "and all the signals are synchronized to within two nanoseconds."
Light travels about 0.6m in 2ns, so this suggests accuracy will be much less than the ~3cm accuracy claimed by the summary. (If you have lots of base stations, you can do rather better than 0.6m, but a factor of 20 would not be feasible.)
Also - I didn't notice anything in the article to support the summary's "to the nearest inch" claim. Did I just miss it, or is this from some other undisclosed source?
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Your welcome!
What about his welcome?
http://www.flepos.be/ but this only covers flanders in belgium but there are similar services for the rest of belgium. The service is free but you need to register. From http://www.gps.oma.be/networks_tutorial.php you can find links to other networks across europe but I don't know if they are free.
With that kind of accuracy, it's almost like cheating. I want it now!
A very accurate time can be determined from WWV by synchronizing with the carrier frequency. The 20MHz (example) carrier for WWV is also a calibrated reference signal that can be used to calibrate your local oscillators or clocks.
The era of modernity and forget alchemist practices.
You know, metric system. Science.
(Sorry my bad French) Je fais parler les Guignols de l'Info. Le pied, quoi.
No long time there will full of location hotspots.
As NocturnHimtatagon has alluded to, data providers only tend to cover specific areas or countries. If Andoid does not provide low enough level access to the GPS hardware to do WAAS then I doubt that you'd be able to do any form of DGPS. Typical consumer-level chips will just output NMEA data, whereas you will need access to at least the raw pseudo-range data (i.e. distance from satellite to receiver) in order to be able to apply the pseudo-range correction (PRC) values. Some provides may provider Code Differential correction data in addition to/instead of PRC but you would still need access to low-level data from the GPS chip.
--- "When you're strange"
Or he could be the one responsible for slashdot's stagnation.
English is not this
I listened to that one. It was an interesting talk including the developers past as a musician IIRC. Then again, Slashdot could do with more Science Show references.
"A very accurate time can be determined from WWV by synchronizing with the carrier frequency."
No, it can't. Frequency != time. Besides, even frequency from the NIST stations is only good to ~1e-7, as received. With much effort, you can get to about 10e-10 in a month. You can do a couple orders of magnitude better with a GPSDO.
"National Security is the chief cause of national insecurity." - Celine's First Law
They should strive make the tech small enough to fit in a keychain, cellphone and wallet.
Robotics? Who needs robotics...
Actually, the first thing I thought of was the ability to locate every firefighter on a fire scene; their location in three dimensions would allow for downed firefighters to be found much quicker.
No. DGPS uses a secondary signal to broadcast an offset, valid for an area a few tens of miles, with diminishing accuracy outside that. RTK combines DGPS with other trickery such as carrier phase enhancement, and a big chunk of extra processing power, to come up with a more accurate position fix.
What you are referring to is the practice of using two sufficiently different carrier frequencies from a single satellite to calculate the ionospheric delay and improve accuracy with a single receiver. This is rarely found outside of military gear. In contrast, DGPS was a civilian enhancement intended to get around the navigational problems caused by selective availability.
"Time Difference Of Arrival". It relies on the fact that radio waves move at the speed of light, which is actually pretty slow. You can easily detect the difference in phase between the signal received by two aerials, and turn this into useful direction information.
You can roll your own TDOA with simple parts available in your local electronics shop - take a look here for a "Whistling Dipole" design that switches between two aerials to determine phase.
Sort of what I was thinking, but...
How exactly does a 2.4 GHz signal that can't penetrate a couple of sheets of drywall go thru meters of hard rock and quartz mineralization?
Current underground radio technology uses backpack-sized VLF transceivers and is designed for surface-to-subsurface communications. Subsurface-to-subsurface is currently not really available without wires, as far as I can find.
Learning HOW to think is more important than learning WHAT to think.
and is commonly known in the industry as a pseudolite...
Hi, folks. I really appreciate the interest that seems to have been generated by our short introductory story to Tom Simonite at MIT Technology Review. It's fascinating to see “the experts” on this site shoot from the hip, with no investigation at all, and immediately assume we're some type of differential correction (no...), a reinvention of Loran (no..), some form of hybrid GPS/Inertial system (no...) or a pseudolite (ahhh HELL no!). Locata is a disruption to the industry because, plain and simple, it's LOCAL GPS without satellites, atomic clocks or the requirement to be “a nation” to provide this functionality. “Local” can be a room, a campus, an airport approach and landing area, or even an entire city in the future. We are the first and only company that can do this. We call it "Your Own GPS".
The most important thing you need to do initially is just FORGET about how it's done (hint it’s ALL about incredible new synchronization technology we’ve invented) because the really smart people will spend their time contemplating what the ramifications of this are for the world of positioning if we’re not full of BS. Full control over your positioning signal is an incredible advance in the art. Give it some thought; it’s worth the effort.
I’m going to give the Slashdot community a little inside peek at Locata. I’ve uploaded a Backgrounder doc to a download site. I think it will allow up to 500 downloads. Have a look and see the future. Enjoy. NunzioG
https://download.yousendit.com/T2dkckhVdGp1Yk9KUmNUQw (I hope Slashdot allows this sort of link on their comments page NG)
What's `a hell of a lot cheaper'? It's possible to use a smartphone as an RTK base station. That's pretty cheap--and shorter-range Wi-Fi GPS devices are even cheaper (the most expensive part in a smartphone is the `phone' module). Even if the recurring fees to subscribe to someone else's service are technically less than the cost of cheap-o base stations, I wonder if the availability of cheap-o base stations may mean that any cost-difference is too small to matter--e.g., a single-digit number of dollars saved or spent over the course of a year is insignificant enough to `get lost in the noise'.
-rozzin.
Any system which needs you to install additional hardware sucks. We can very well use the system planes used before GPS was deployed. INS using compasses and gyroscopes. You just need everyone to have a compass and gyroscope in their pockets. Wait everyone with an iPhone4 or a NexusS already does. Wifi based GPS enhancements are the buggy whip manufacturers of our day. Even the best and most accurate will be going out of business.
**Life is too short to be serious**
There is a lot of confusion among the early commenters. Some think this is a form of differential GPS, some think this is a network of WiFi devices, or a hybrid of WiFi and FM radio.
It appears to be none of the above.
It most likely is a pseudo-lite (a terrestrial device which mimics a satellite), except that it does not operate in the GPS (L1 or L2) band(s). The government, researchers, FAA and Air Force (which runs GPS) are working on real pseudolites which may run in the GPS bands. But this private company couldn't get rights to do that, so they are transmitting in 'the same band(s) used by WiFi. That is, they are broadcasting spread spectrum signals in the ISM band(s).
They apparently scatter a number of these, at highly precise locations, and a compatible user device would then listen to several and calculate its own position. Since their geometry is as flat as the nearby terrain, they will have very poor altitude accuracy, but because they don't have bending or delays in the atmosphere (or rather, those inaccuracies are trivial in comparison), they will likely have very good 2D accuracy.
Notice that things flying over the top of these devices would likely have good 3D (the geometry improves for them).
What is less clear is why this is preferable to using DGPS. DGPS is a 'station' at a known location which can measure the errors of each satellite (including bending/delay) and transmits corrections to nearby devices. DGPS is a government service in many areas, I believe, but can be set up as a private service, too.
The one real liability to the new Locata system, if I understand it (and I probably don't) is that they don't necessarily use GPS time. One of the really fabulous things about GPS is that it established a world-wide synchronous, highly accurate clock. In many applications that may not matter. It does for a lot of systems which rely on GPS time (too many to mention nowadays).
Also from TFA:
Enge says it is likely that these pseudolites will rely on time signals sent over the Internet, using a new protocol that enables high accuracy.
He doesn't say, but I assume he is talking about Precision Time Protocol, which allows for sub-microsecond precision. With that, the claim of 3cm is totally realistic.
I'll agree that I'm making some assumptions since this is a shit article.
However, the main takeaway from this is the idea of using devices without an on-board atomic clock & instead using a clock that must stay in sync. It is a neat idea & might work, but I wouldn't want anyone's life to depend on it.
Grammer Nazis - I mod you "troll" unless you actually add something on-topic. Yes, I know I have mispellings in my sig.
In an open cavern, perhaps. In a much more typical non-straight tunnel with pipework, moving objects, intermittent "rooms" with "pillar and stall" workings ... I suspect that you'd need to spend so much time installing and calibrating equipment that you'd be as well off sending your existing surveying team around with modern surveying equipment like theodolites, LIDAR scanners, tape measures, computerised data acquisition and GIS.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"