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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.'"
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
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.
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.
Millimeter accuracy in 3 dimensions would open up a lot of possibilities for use in robotics.
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.
What is new here?
Complete lack of dependency upon satellite signals?
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
so they reinvented 1950's tech
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"
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.