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View Full Version : No more GPS satellites? Now there's something better.



Roger E. Moore
2018-Nov-09, 07:28 PM
This looks important, as in, we don't need GPS satellites anymore.


https://phys.org/news/2018-11-quantum-compass-satellites.html

Quantum 'compass' could allow navigation without relying on satellites

November 9, 2018 by Hayley Dunning, Imperial College London

The UK's first quantum accelerometer for navigation has been demonstrated by a team from Imperial College London and M Squared. Most navigation today relies on a global navigation satellite system (GNSS), such as GPS, which sends and receives signals from satellites orbiting the Earth. The quantum accelerometer is a self-contained system that does not rely on any external signals.

This is particularly important because satellite signals can become unavailable due to blockages such as tall buildings, or can be jammed, imitated or denied preventing accurate navigation. One day of denial of the satellite service would cost the UK 1 billion.

Now, for the first time, a UK team has demonstrated a transportable, standalone quantum accelerometer at the National Quantum Technologies Showcase, an event demonstrating the technological progress arising from the UK National Quantum Technologies Programme a 270m UK Government investment over five years.

The device, built by Imperial College London and M Squared, was funded through the Defence Science and Technology Laboratory's Future Sensing and Situational Awareness Programme, the Engineering and Physical Sciences Research Council, and Innovate UK. It represents the UK's first commercially viable quantum accelerometer, which could be used for navigation.

Accelerometers measure how an object's velocity changes over time. With this, and the starting point of the object, the new position can be calculated.

SkepticJ
2018-Nov-09, 09:58 PM
It's very cool, but it won't be replacing GPS in most applications--bulky and costly equipment.

Military subs will get an upgrade to their inertial navigation systems though.

WaxRubiks
2018-Nov-09, 10:19 PM
Is it bulky?

A less bulky system could be an ordinary acceleration measuring device with the ability to read road signs, and base its location on the assumption that the vehicle is on a road on its map, plus using the car's accelerometer?

headrush
2018-Dec-29, 02:21 PM
With regards to GPS, I keep seeing references to sending signals to satellites. As far as I'm aware this doesn't happen. The GPS receiver simply checks the time broadcast by each visible satellite and extrapolates it's own geographical position from the difference between the broadcast time and the current time (which gives the receivers distance from each satellite).

This is what bugs me about many TV cop shows, when they supposedly track perps using their GPS transmissions. All consumers GPS units are passive receivers not transmitters. The usual way of tracking is by sending GPS data via the cellphone network.

ETA - Or just using the cellphone network itself as a rough approximation. (RDF)

Ken G
2018-Dec-29, 03:46 PM
Accelerometers measure how an object's velocity changes over time. With this, and the starting point of the object, the new position can be calculated.
Why would you not also need to know the acceleration of gravity at every point through which the accelerometer moved?

grant hutchison
2018-Dec-29, 03:55 PM
A less bulky system could be an ordinary acceleration measuring device with the ability to read road signs, and base its location on the assumption that the vehicle is on a road on its map, plus using the car's accelerometer?Or just a map and an ability to read road signs. Oh, hang on, I've got that already.

The problem, of course, is navigating in places where there aren't any road signs.

Grant Hutchison

swampyankee
2018-Dec-29, 04:45 PM
Or just a map and an ability to read road signs. Oh, hang on, I've got that already.

The problem, of course, is navigating in places where there aren't any road signs.

Grant Hutchison


Or the road signs aren’t readable. I have not been able to read street signs at night for about fifty years.

grant hutchison
2018-Dec-29, 05:31 PM
Or the road signs aren’t readable. I have not been able to read street signs at night for about fifty years.That's a problem.
One of my earliest memories is of a nighttime drive along country roads in a snowstorm. My father would stop the car at road junctions and get out with a torch so that he could read the writing on the fingerpost signs. Took a while to get home, but that sort of thing was pretty routine at the time.

Grant Hutchison

swampyankee
2018-Dec-29, 09:06 PM
That's a problem.
One of my earliest memories is of a nighttime drive along country roads in a snowstorm. My father would stop the car at road junctions and get out with a torch so that he could read the writing on the fingerpost signs. Took a while to get home, but that sort of thing was pretty routine at the time.

Grant Hutchison

It’s a problem my ophthalmologists have been aware of; my corrected vision is fine. It’s fairly common in people who need glasses.

Trebuchet
2018-Dec-31, 03:39 PM
I've twice in the last two days missed a turn in a city I'm only semi-familiar with due to signs hiding behind bushes. The GPS in the car didn't really help.
This new system is large now but can be expected to be reduced, although it's not clear how much. I'd guess it won't be in my phone during my lifetime.
I find the use of "quantum" kind of annoying. The word's been ruined by the likes of Deepak Chopra.

Ken G
2018-Dec-31, 04:09 PM
I still don't see how the technology would even work. Seems to me it would need to have programmed into it the acceleration of gravity everywhere the instrument goes, which would obviously require knowing where you are, perhaps by using GPS!

Geo Kaplan
2019-Jan-01, 12:17 AM
I still don't see how the technology would even work. Seems to me it would need to have programmed into it the acceleration of gravity everywhere the instrument goes, which would obviously require knowing where you are, perhaps by using GPS!

On top of that, there remains the additional problem associated with having to integrate twice to get position. Any nonzero offset in the electronics will inevitably integrate over time to overwhelm the position signal. I don't think that invoking "quantum" magically solves that problem.

Ken G
2019-Jan-01, 01:17 AM
Yeah, it doesn't sound like double integration is an easy way to minimize errors! On the other hand, had someone suggested 100 years ago that the best way to navigate would turn out to be receiving signals from orbiting satellites, we would probably have told them they were nuts.

swampyankee
2019-Jan-01, 04:21 AM
I still don't see how the technology would even work. Seems to me it would need to have programmed into it the acceleration of gravity everywhere the instrument goes, which would obviously require knowing where you are, perhaps by using GPS!

Do you mean this technology or inertial navigation, in general? If the latter, inertial nav systems have been in military and commercial use since the 1960s.

Ken G
2019-Jan-01, 05:49 AM
Do you mean this technology or inertial navigation, in general? If the latter, inertial nav systems have been in military and commercial use since the 1960s.
And I'm not sure how they do it, but it seems obvious they need to know the local acceleration of gravity in order to work. For example, if the accelerometer reads zero, the object is in free fall, but knowing that an object is in free fall doesn't tell you much about where you are if you don't know the local acceleration of gravity. Perhaps the systems maintain a memory of the gravitational acceleration everywhere, or a model for calculating it. The issue of error brings in uncertainties in the knowledge of that gravity field, the integration errors, and so on-- so one wonders if "quantum precision" in the device is really all that helpful. Perhaps it reduces the integration errors, leaving only the uncertainties in the local gravitational acceleration. But I was only kidding about using GPS to know where you are, you can use your own readings as long as you continually update the local gravity.

Ken G
2019-Jan-01, 06:42 AM
I found an article, https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1559-3584.1997.tb03201.x , with some of the answers-- they maintain a second system to measure the "local gravity anomaly", which works in concert with inertial navigation. So apparently, they use three things-- the inertial nav system, an overall gravity map, and some kind of way to correct the local gravity map, I have no idea how you would do that.

Jens
2019-Jan-01, 08:27 AM
I find the use of "quantum" kind of annoying. The word's been ruined by the likes of Deepak Chopra.

I find it annoying as well. I wish we could get over it, but Im afraid it would require a quantum leap in the way we think.

Oops.


Sent from my iPhone using Tapatalk

Ken G
2019-Jan-01, 03:42 PM
But get used to it, quantum computing is coming!

profloater
2019-Jan-01, 07:39 PM
I find it annoying as well. I wish we could get over it, but Im afraid it would require a quantum leap in the way we think.

Oops.


Sent from my iPhone using Tapatalk

:) I fear we have lost that quantum battle, as we have with "it's in our DNA" and entering "Unchartered Waters" and "do the Math"

ngc3314
2019-Jan-02, 08:48 PM
The problem, of course, is navigating in places where there aren't any road signs.

An example from first responders after our mammoth 2011 tornado - there were substantially-sized neighborhoods where ambulances or police had trouble responding to 911 calls because there were no remaining road signs and many familiar landmarks that the callers could have used as markers were also gone.

publiusr
2019-Jan-04, 08:11 PM
The GPS sats are improving:

"With 500 times the transmitter power of current GPS systems, the Block III satellites will benefit from improved navigational warfare capabilities, with three times better accuracy and eight times better anti-jamming functionality, enabling them to shut off GPS services to limited geographical locations, whilst maintaining provision for U.S. and allied forces."

https://www.americaspace.com/2018/12/23/last-spacex-launch-of-2018-delivers-inaugural-gps-iii-satellite-to-orbit/

"With 500 times the transmitter power of current GPS systems, the Block III satellites will benefit from improved navigational warfare capabilities, with three times better accuracy and eight times better anti-jamming functionality, enabling them to shut off GPS services to limited geographical locations, whilst maintaining provision for U.S. and allied forces."


Now if this could be mass produced
https://physicsworld.com/a/neutrino-based-communication-is-a-first/
---that and the new compass together may harm the spacelaunch industry.

Ken G
2019-Jan-05, 08:21 PM
One more thing to get hacked.