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Centimeter-Resolution GPS For Smartphones, VR, Drones
agent elevator writes: UT Austin engineers have come up with a software fix that corrects for the errors GPS has when using the tiny antennas on smartphones. They demoed it using a VR setup and got 2-cm accuracy. For now it runs on a separate processor from the smartphone, but they say they'll fix that. The demo appears to have been done on a rooftop. VR. Outside. On a roof. Doesn't seem like a good idea, does it?
Put a question in the summary that only makes sense if you RTFA. Nice.
It is unwise to ascribe motive
The cell phone GPS antennae are tiny they catch the signal from the satellite and also many reflections. These reflections confuse the processor trying to fix the distance between itself and the satellite. They seem to have developed some signal processing algorithm that would remove these reflections. The article is skimpy on details.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Well, as long as you don't get closer than 2 centimeters from the edge.
That would be a good test for a GPS product; have someone navigate a dangerous area blindfolded using it's directions.
there's no fudging the data if it's a fail this way.
if this is supposed to be a new economy, how come they still want my old fashioned money?
Nope, SA is turned off even in war zones, in fact the newest birds don't even have the SA feature.
True, Selective Availability is disabled or otherwise not available on the new satellites, but the government still retains the ability to deny GPS on a regional basis.
See :
"Why are you turning [SA] off?
A. The decision to end the degradation of civil accuracy on a global level was made by the President based on a Secretary of Defense recommendation coordinated with all applicable departments and agencies. This decision is based on the U.S. military commitment to develop and employ technologies to deny the civil services of GPS on a regional basis. Under this approach, it will be possible to deny GPS to potential adversaries in areas of operations while preserving the peaceful use of GPS services outside those areas"
That said, civilian GPS receivers are often quite a bit better, more handy, and more advanced than military ones and a lot of soldiers use them in combat areas. Sure, the military ones are more rugged and get the encrypted military-only channel with better accuracy, but sub-meter accuracy is only really needed for smart bombs and the like. It's less useful for driving a Humvee down the street somewhere or finding out how to get back to base. Handheld civil GPS receivers are typically accurate down to the 3-5 meter range, which is only slightly worse than the military ones.
Denying civil GPS signals in certain regions would almost certainly make things worse for US soldiers, so it's extremely unlikely that the military would ever do regional denial of civil GPS except in the most extreme situations. Even then it'd have limited effect because GLONASS (Russian), Compass (Chinese), and Galileo (EU) are or will soon be perfectly viable alternatives that bad guys could use for guidance.
if you are on a rooftop.
I have made my diploma in geodesy and if it would be so easy to get 2 cm with smartphone everywhere then it would be rolled out already. What they are showing is known and realized for like 6 years already, so nothing new. The positions problems will still persist on street level where like 99% of all peoples move and cars drive? The problem is not the antenna its the signal interruptions and multi-path reflections you have on the streets that you cannot simply fix with software as the amount of unique signals is limited.
It will actually be fixed by more satellites integrated into one software equalization equation and different signal modulation.
The first is taken care of by the GPS race between all superpowers entangled in it. By 2018 we will have around ~100 GP(S) Satellites in stationary or modular orbits. The only limiting factor here is the software of vendors which has to align and process the public signals GLONASS (RU), GALILEO (EU), GPS (US), BEIDU (CHINA), Indian and Japan signals. Which no one does atm, it is done at university level (for instance german TU Dresden).
The second one could improve position but just if all countries involved in GPS development and evolution would work together but actually they are not. Instead they compete for the frequencies ...very retarded game but that's another story.
What people need to understand is that most position software out there barely manage to get a better position out of GPS + GLONASS. There is nearly non that handles the four major systems because even these systems have, based on different earth models, different results for the same position.
https://radionavlab.ae.utexas.edu/images/stories/files/papers/ion2014Pesyna.pdf
We can be tracked with decimeter precision. Yay. I'm sure it won't be used against us. Carry on.
They use RTK technology. It doesn't rely on the same data as GPS or dGPS. It isn't new techology. And it wouldn't matter if the DOD screwed with the dGPS signal.
What is new is just what the article talked about. They have found a way, through 6 years of developing the software, to use a cheap antennae to capture signals. Prior to the software development, cheap antennae couldn't be used because they allowed for too much signal degradation. Their solution is their software, which they have apparently perfected to the point where it can recognize and correct or mistakes caused by the antennae.
My understanding of RTK is that it isn't useful for navigation, but is very useful and accurate in obtaining your position(while not moving) This is because it relies on a base station in addition to the other receiver.
Part of the problem that isn't addressed in the summary is that to have a cm accurate position you also need to have an oscillator that is accurate in the tens of picoseconds range.
From the article:
> The clock attached to the external front-end was an oven-controlled crystal oscillator (OCXO), which has much greater stability than the low-cost oscillators used to drive GNSS signal sampling within smartphones.
An OCXO is far more expensive than a smartphone manufacturer will happily absorb (~$30). It is also constantly heating the crystal so your battery life gets thrown out the window too.
GPS manufacturers very carefully select their cheaper TCXO chips in order to get nanosecond accuracy. Special tricks are used to get sufficient DAC resolution on the voltage control in order to steer them to the correct level. I have been out of the industry for several years but I would be shocked if there has been a 100x improvement in quality without hearing anything about it.
Well if it is on a smart phone having a data connection would allow the retrieval of the necessary data so it may be that who ever wrote the article isn't really aware of what is needed. Yes the antennas in phones suck, as do the GPS chipsets. Also whoever wrote the article doesn't' seem to know much about antennas as I use some very small but pretty good ones with nice uBlox LEA-6t module in my home built setup for RTK and they work great.
I wonder, after carefully reading the article, if they are discussing getting 2cm resolution instead of 2cm accuracy since getting a better resolution would seem to be doable with a better antenna and nothing else. Also I don't believe any of the GPS modules in cellphones are capable of outputting L2 carrier phase data or raw pseudo range data which would be needed for RTK so at best they could do DGPS which is a lot less software intensive. Usually the giant dinner plate thing isn't the antenna but a shield that is meant to prevent most of the multipath problems. a piece of grounded sheet metal works just as well. On newer modules it is also handled in software but the shielding still makes things easier as it filters most of the reflected signals coming from below.
Since the last time I posted about this stuff people wanted to know where to get one here is the discussion I found that got me pointed in the right direction.
Time to offend someone