Earlier quoted context omitted.
The US military is working on a device that can use stars to determine location even during the day.
> The US military is working on a device that can use stars to determine location even during the day. They already developed a device that could do that in the 60s, but it was quite large: https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Astro... https://timeandnavigation.si.edu/multimedia-asset/nortronics... Do you have a source for the one you say they're working on? Is more portable or hand-held?
Royal Navy says quantum navigation test a success
251–260 of 279 posts
Re: Royal Navy says quantum navigation test a success
#252Do we know if any animals navigate this way, or is that generally limited to following the magnetic field of the Earth?
Re: Royal Navy says quantum navigation test a success
#253Earlier quoted context omitted.
Naive question: don't need a precise initial location to tell subsequent locations using an accelerometer? This doesn't fully obviate GPS then?
Ports don't move very often.
Ports are big so that wouldn't be very accurate.
I bet they do have GPS, they're just less dependent on it.
Re: Royal Navy says quantum navigation test a success
#254Earlier quoted context omitted.
Sources of Noise ?! Doesn't that mean that the gravitational field is an information storage and transmission medium; a signal channel? Is it lossy? Is there a routable signal path to block harassing calls? Is it slower or cheaper than nonlocal entanglement; like quantum radar? What is the minimum energy necessary to cause a propagating thresholdable-as-binary pertubation of a gravitational field?
I think you may be engaged in circular reasoning, here. Noise, by definition, is what can’t be modeled. The idea would be to have some model of the signal produced by the submarine’s machinery, and use that to reduce the noise (increase SNR) to the point that this nav system becomes useful.
Of course we would always filter out noise completely if it was that easy to model. My point was that some components of that noise (for example the moving parts of the engines) can be modeled very accurately.
Re: Royal Navy says quantum navigation test a success
#255Earlier quoted context omitted.
A typical sub drifts by only a few tens of meters per day - obviously this builds up . The point of the BEC gravity map is to reduce this inaccuracy an order of magnitude, thereby extending the subsurface range of the subs.
But how would you do this? Sensor fusion with inertial sensors is well understood, how do you fuse g into the equation to improve things?
By having a base map of the gravity of the ocean floor. Picture a contour map, but for values of g.
Same as if you were navigating based on a physical contour map of the ocean floor, except that getting an accurate depth like that in deep waters isn’t possible, and in shallow waters requires sonar.
Re: Royal Navy says quantum navigation test a success
#256Earlier quoted context omitted.
From layman to former submariner, a very silly question I've always wondered about and that I now have the rare chance to ask someone with some expertise: Do submarines mostly roam about or do they tend to stay relatively quiet/idle? I always imagined submarines constantly moving about but at the same time it feels like a waste of fuel.
Ohio-class submarines (the ones that carry missiles): when they're "on station" they're just tooling around staying as quiet as they can. There's a relevant phrase for them: "Three knots to nowhere" Los Angeles and Virginia-class submarines are always doing something: doing exercises, transiting from one location to another, etc. And typically multiple things at once. While the boat is transiting from an exercise are…
What about diesel boats? They are exclusively attack subs but fuel is relatively limited.
Re: Royal Navy says quantum navigation test a success
#257Good for them. Navigation relying solely on GPS always struck me as extremely stupid for the very reasons mentioned in the article.
Re: Royal Navy says quantum navigation test a success
#258Earlier quoted context omitted.
Ohio-class submarines (the ones that carry missiles): when they're "on station" they're just tooling around staying as quiet as they can. There's a relevant phrase for them: "Three knots to nowhere" Los Angeles and Virginia-class submarines are always doing something: doing exercises, transiting from one location to another, etc. And typically multiple things at once. While the boat is transiting from an exercise are…
What about diesel boats? They are exclusively attack subs but fuel is relatively limited.
The US doesn't have diesel boats anymore. Though other countries (like Australia) do.
Re: Royal Navy says quantum navigation test a success
#259Earlier quoted context omitted.
Submarines do not have to surface to get a GPS lock. https://en.wikipedia.org/wiki/Submarine_navigation "On the surface or at periscope depth, submarines have used these methods to fix their position"...GPS being one of them. A submarine can also navigate by the stars without surfacing. https://www.usni.org/magazines/proceedings/2021/october/navi... "This is precisely the information required by the traditional metho…
Why was I downvoted please? I provided facts to my counterpoint.
Never attribute to malice what can be attributed to ignorance.
Also, look up the HN guidelines on debating your downvotes.
Welcome to HN!
Re: Royal Navy says quantum navigation test a success
#260Earlier quoted context omitted.
Inertial navigation is a form of dead reckoning. It needs periodic updates (GPS fixes) to stay accurate. If this however works like some other commenters have theorized (by finding reliable matches to the known contour of the bottom of the ocean), it's not a form of dead reckoning and can instead be used as a fix for dead reckoning.
I don’t know how that would work. Most of the ocean (ca. 75% is unmapped) and is constantly changing.
Possibly, military submarines are interested in only a small part of the ocean. The Strait of Hormuz probably is well-mapped; some spot in the middle of the Indian Ocean might be unneeded.