It’s a naval chart that would not require surfacing.
A French postdoc in my lab swore this was the moneymaker for our entire subfield, and it seems he was on to something …
> one of the primary reasons subs need to surface , in order to GPS lock
While getting a GPS position is helpful, the primary reason a submarine goes to periscope depth regularly is for communications. The Navy needs to send information to submarines and know that they'll get it and take action within a certain timeframe. That's by far the primary driver.
Towed sensors and multiple passes over known calibration zones?
The shaft and screw are confined to the end of the sub. A navigation instrument like this would not be in the engineroom.
In robotics parlance, this is the difference between dead reckoning versus SLAM (simultaneous localization and mapping).
Huge game changer if true.
Other sources say this is about inertial navigation, not based on charts.
"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."
https://www.imperial.ac.uk/news/188973/quantum-compass-could...
I think with any INS system, if you want to be very accurate you need charts of gravitational anomalies. So these seem like one and the same to me.
Do we somehow already have that super-accurate "map of g"? Wouldn't one already have to exist to be able to use quantum navigation? Moreover, would it not also require integration with a gyro and a lot of history to be able to know, for instance, which place it's at of many in any given ocean where g = 9.8100023?
Does g really vary that much that you can figure out where you are with it with sufficient accuracy to do military stuff?
I am a ham radio operator and was thinking about novel forms of signal propagation.
I landed on the idea of gravitons. Could gravitonic signal propagation be done somehow? While researching, I keep coming across familiar terms I know from radio land.
Just curious if the fields here could be harnessed for communication. Thanks.
Not quite possible today, though, as others have pointed out
It's conceptually similar, but they didn't use quantum gravity mapping in the 50s.
Huh? Wouldn't it be enough to send some small thing connected by thin wires or wirelessly to the submarine (lasers, ultrasound, whatever) that could aquire location and communicate it? Given military budgets it could probably even be disposable.
Leaving beacons in areas of interest also seems like a good idea. With good encryption their signal could be indistinguishable from noise happening around it.
They use audio for short-range underwater communication, but this has side effect of giving away position.
US also built giant ELF (extra low frequency) transmitter to send orders to subs which operated till 2004.
Fun fact: subs have all necessary codes to launch nuclear strike on board since there is no way to transmit these code to them if they are submerged.
Additionally if they communicate through radio, you're back to the same problem because it's the thousand feet of water that blocks most radio waves. If they communicate via ultrasound you've just tied your sub to a nearby active sonar source. If they communicate via laser you have to be very close otherwise the power of the laser creates sonar detectable variations in the water near the sub.
They do, using either tethered buoys or 'buoyant cable antennas' (the cable is the antenna and is itself buoyant) They can use these without coming to periscope depth, or even slowing down.
it would seem the Total Perspective Vortex has obvious military applications
https://www.urbandictionary.com/define.php?term=Total%20Pers...
Sensitive enough to, say, detect the movement of something moving at a known frequency on the other side of the planet?
Are we on the edge of gravitation based communication channels?
Sensitive detectors can measure differences in hundreds of millionths (10^-8 parts) or around .1 um/s^2.
A 1 million tonne mass on the other side of the earth will create a TOTAL acceleration of 4*10^-16. Changes in that will not be detectable.
The more mass necessary, the more energy you'll need to send messages.
Unless the detection is extremely accurate, you would be better off spending that energy in electromagnetic radiation that bounces off the atmosphere.
Why do you think the concentration of iron in magma would not be evenly distributed throughout the mantle?
"n condensed matter physics, a Bose–Einstein condensate (BEC) is a state of matter that is typically formed when a gas of bosons at very low densities is cooled to temperatures very close to absolute zero (−273.15 °C or −459.67 °F)..."
I guess, a special device is needed. The size of such device will be in thousands of mobile phones just in volume needed.
Yet, it is feasible. ;)
https://www.gla.ac.uk/research/beacons/nanoquantum/wee-gglas...
One important distinction is between measuring gravity (generally, acceleration in the vertical direction) and the gravity gradient. The latter is generally easier and more useful for navigation.
I believe in the book version of the Hunt for Red October by Tom Clancy, they mention that the Soviets did something similar but using a magnetometer.
Super cool to see the newest versions of this are going from sci-fi to fact.
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 method of celestial navigation, and it is accomplished without the need to surface or use a sextant!"
We need accurate maps of the geoid for a lot of different reasons. (Military as well as civilian. Potential fields geophysics is super useful for all kinds of different geologic use cases, and regardless, if you want to target an ICBM, you need an accurate geoid.)
However, a super precise gravimeter doesn't help much. We have more precision than we can use already. Rather ancient spring-based instruments from 100 years ago can actually still give more precision than we can use in many cases. Modern ship-borne gravity instruments work on different principles, but the signal is very noisy for the same external reasons.
The biggest issue is that you also need to know absolute elevation very precisely to use the measurement of g that you get. A few millimeters of error in elevation significantly changes the anomaly measurement you make. Sure, submarines can get accurate hydrostatic measurements of depth, but those assume a lot of things and critically aren't absolute. The ocean has currents - that's another way of saying that the surface of the ocean isn't "sea level". Those vary through time and would require satellite information to correct for. However, once you get down in the weeds, it gets tougher still.
Remember that we're dealing with an inverse square distance relationship. Things close by matter quite a lot.
People nearby standing in different positions? That actually does affect things. Easy enough to mount the instrument away from people, though. Different distributions of mass in the submarine? Also affects the measurement. You can correct for all of these in various ways, though, so long as you have information on it. It's just more complexity and another source of noise.
In the end, the "free air anomaly" measurement you'd be correcting things to is an bathymetry map, to the first order. If there's a landslide, that affects things quite a bit, and those happen all the time.
Finally, you'd be matching a "fingerprint" time series measurement as you travel to a pre made map. That's a non unique relationship. You'd have heading/etc information to help the non uniqueness part significantly, but when things don't vary much (i.e flat topography and not a ton varying geologically), you don't have much of a unique signal to match to.
At any rate, it's a very useful tool for many other things, but I'm skeptical it could be turned into a precise navigational aid. In combination with traditional gyroscopic/etc measurements of heading and distance, it could help constrain uncertainty, but it's not an independent measurement and it's relatively noisy.
Now that I think about it, though, a fully passive "seamount proximity sensor" is rather useful, and that's something you'd get even with a noisy signal...
I don't think so. What you are saying is true if for some reason you want to work with absolute values, but nobody would do that. You measure many data points as your submarine flies over the landscape for a time, and then you match the measured curve with predicted curves from bathymetric maps. This is an optimisation problem where you try to find the best match. Precise elevation is an output from this process not an input requirement.
> but when things don't vary much (i.e flat topography and not a ton varying geologically), you don't have much of a unique signal to match to
100%. This is also true for cruise missiles which fly by TERCOM[1]. And there is an interesting consequence to it. Submarines and cruise missiles don't just bumble around randomly. The navigators also know this limitation so they set trajectories which plays to their strength. In the case of the cruise missile planners they have tools to evaluate the navigational quality of a terrain contour matching algorithm over a proposed trajectory with Monte Carlo methods. Probably submariners have the same.
This means in practice you can know that the submarines are more likely to take certain routes. They will prefer approaching from hilly terrain over flat, but also over extended flat areas they will prefer to overfly butes to regain navigational accuracy. This of course won't tell you precisely where the submarine is, but can help an adversary more economically allocate their ASW assets.
> At any rate, it's a very useful tool for many other things, but I'm skeptical it could be turned into a precise navigational aid
Yeah. I mean I heard that people proposed to make measurements of stars to find your location. The fools. Haven't they heard of clouds? Sometimes you can't see as far as your own nose for days.
Every navigational system ever devised have limitations and peculiarities. If you are comparing gravitational tercom with the ease and quality and simplicity of GPS then of course it will look crude and cumbersome. But of course GPS adds other complications and dangers to the life of a submariner. Used well, and in the right circumstances it can be potentially very valuable technique.
Edit: Seems like there's another company that's doing the same thing [4] with BSEs [5].
[1] https://physics.stackexchange.com/questions/570707/why-is-ru...
[2] https://en.wikipedia.org/wiki/TERCOM
[3] https://earthobservatory.nasa.gov/images/87189/seafloor-feat...
https://www.livescience.com/54667-bose-einstein-condensate.h...
This would be incorrect.
It is just a very accurate, unproven in the field, accelerometer.
https://www.youtube.com/watch?v=XwKKOPd-5cU - "Royal Navy's experimental ship carries out first trial of quantum navigation system"
"The quantum accelerometer uses ultracold atoms to make highly accurate measurements. When cooled to extremely low temperatures the atoms start to display their ‘quantum’ nature, resulting in wave-like properties. As the atoms move through the sensor, an ‘optical ruler’ is formed by using a series of laser pulses. This allows the acceleration of the atoms to be precisely measured."
The page claims that this device attempts to measure acceleration accurately enough that position can be determined (by integrating over time, twice).
[0]https://www.imperial.ac.uk/centre-for-cold-matter/people/
Initially in https://bigbangtheory.fandom.com/wiki/The_Positive_Negative_...
Then later https://www.youtube.com/watch?v=az44pMHvUYk
There's something called a "quantum gyroscope".[1] Those exist as lab devices. One good enough for a submarine seems not too big a jump.
Aha! So it might be able to detect other submarines, even if they use some stealth tech.
There are a few types of passive quantum navigation systems, but the principle is similar to a using a stopwatch and an old-school gyroscope to measure changes in momentum and then calculating your position via dead reckoning. It just sounds like quantum methods have let them get a lot more precise.
This is actually pretty exciting from the perspective of deep sea exploration. Once you get below the surface there's no GPS and it becomes difficult to fix your position. With one of these, you'd have something like GPS no matter how deep you go.
[1]https://www.nist.gov/noac/technology/time-and-frequency/atom...
[1] https://www.ion.org/museum/item_view.cfm?cid=2&scid=4&iid=4
https://news.sky.com/story/royal-navys-experimental-ship-car...
Not really. Subs don’t move that fast in those tight of conditions. One wrong move and the sub bumps the canyon wall making a bunch of noise. Unless they are in actively hostile waters, it just means loss of stealth and the sub needs to choose a new location to lurk.
"On 8 January 2005 at 02:43 GMT, San Francisco collided with an undersea mountain about 364 nautical miles (675 km) southeast of Guam while operating at flank (maximum) speed at a depth of 525 feet (160 m)."
From the same article:
“The collision was so serious that the vessel was almost lost; accounts detail a desperate struggle for positive buoyancy to surface after the forward ballast tanks were ruptured.”
I doubt these are problems any submarine crew wants to deal with, even at slow speeds. Besides, one sharp edge at the sides will open her right up like a tin can.
(I'm sorry)
But seriously, this article is light on details. Is this just fancy dead-reckoning?
I'd expect it to be light on details. It is a project funded by the Royal Navy for next-generation navigation. Thye don't really want to give away details other than, "we have this"
A recent TV news report covered this in the UK. The only thing they could show was an prototype in a lab setting and a sealed white box on the test platform boat.
Can a submerged military submarine let divers "out", and / or divers "in"?
Do they have air locks / water locks?
It would seem possible, enormously dependent on the depth of the submarine. Not just from the perspective of the integrity of the giant uboat but also the integrity of divers.
In movies (which are always "accurate") they put people into torpedo tubes. Which I believe do feature some form of an air locks and ports to open and close. Not sure a person would fit, or if it is physically possible given the operation of the tube.
If possible, can they enter the same way?
My second question is if you can do deep sea fishing? (while submerged) Have fresh as can be sushi?
I figure if you can let a person in and out, that person could go hunt fish and bring it back.
They dont have windows but from sonar does pick up some sea creatures. You could possibly have a harpoon with a sensor on it you could extend to catch fish.
It just seems it ought to be possible. With a nuclear submarine, I think, one of the limits to how long you can operate before requiring supplies is food. I hope a nuclear submarine has a way to creating fresh water from salt water as benefit for having a reactor. at least.
Aesthetics are key for quantum navigation /s
Probably the biggest issue with INSs is accuracy of the raw IMU measurements. The acceleration must be integrated twice. That means any error in the measurement gets exponentially larger with time. Rotation velocity measurements are integrated only once (some IMUs measure absolute orientation but it is not the case here) so the error does not explode as fast. Is is the combination with translation that is problematic. If you rotate around vertical axis by 90deg +/- 1% and then travel for 1000km +/- 1% the rotation accuracy will cause bigger error in final location.
To have an INS capable of long time operation without any other means of drift correction one has to nail many other things.
- Gravitational constant varies and you have to have an accurate map of it. We might not have a good enough one. I don't know. The subs could collect their measurements and perform a large scale optimization to increase the accuracy of this map.
- The rotation of earth gets added to the rotation speed measurements. The rotation is not constant (hence the leap seconds from now and then). We have to be able to extrapolate it well enough.
- Sampling rate of the quantum IMU has to be high enough. How usefull is the most precise measurement if you can measure only once in 10 minutes? Traditional IMUs sample at 1 kHz and more.
- Does the new quantum gyroscope add enough value to the accuracy of the final IMU compared to Fibre-optic gyroscopes? They are incredibly accurate as they are based on laser interferometry and then can sample at high frequency. Plus they are an established technology which partially benefits from economy of scale [5] because they are used in airplanes [6].
- The measurements of both rotation velocity and acceleration have to be measured in 3 axes. Are the relative orientations and translations of those axes stable enough as the device moves?
- Is the noise present in the measurements corelated to something or is it truly random? The corelation could mean an systematic error to the state estimate.
- You will likely also have to have an atomic clock on board labeling each IMU measurement as soon as it is made. But this is not a problem nowadays as one can have a small Rubidium-based atomic clock in a package starting to resemble a chip [2] [3] [4].
- And of course you will need enough computing power to calculate everything. I'm not sure how modern hardware they are allowed on board of nuclear-carrying subs. This is slight problem for things like Mars rover as due to the testing requirements the main chip can be easily 30 years old when the rocket is launched [7].
Also, the situation is not as bad as we can utilize the sensor fusion and correct lots of errors caused by IMU measurements. From the top of my head one can obviously measure water pressure which estimates depth (with some error). Sea bed topology could be other type of measurement but my guess is that this measurement is too crude compared to the accuracy of the quantum-based INS.
[1] https://www.imperial.ac.uk/centre-for-cold-matter/research/q...
[2] https://eu.mouser.com/new/microchip/microchip-macsa5x-atomic...
[3] https://www.sparkfun.com/products/14830
[4] https://www.accubeat.com/nano-atomic-clock
[5] https://emcore.com/wp-content/uploads/2016/12/EMCORE-Commerc...
[6] https://www.airbus.com/en/products-services/space/equipment/...
[7] https://bigthink.com/hard-science/perseverance-rover-brain/
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.
Here's an example of something you don't hear about: AI Assisted Battlefield Tactics. While I've never heard of it (certainly not in the press), I simply assume that they're doing research on it. I base this assumption on the AlphaStar AI from DeepMind that would completely pawn Grand Masters in the game of StarCraft 2.
While AlphaStar is obviously designed for a game with very set rules and weights, I don't think it's unfeasible to develop a similar military AI that could also work in the shifting tactics of the modern battlefields.
The result would be comical, as larger armies without such an AI would always lose to someone with that AI, even if their army is much smaller or seemingly technologically disadvantaged. And it would seem that there's at least one such country in such a position today, which is also heavily supported by the NATO.
Now, my last argument for why alphastar wasn’t some sort of brilliant tactician was that eventually people figured out that it’s susceptible to all the same problems a normal bot is: you can dart a warp prism in and out of its vision and it will send its army back and forth, you can confuse it by going mass raven/PF etc. and it’s completely unable to adapt. So in conclusion, no: AlphaStar doesn’t say anything one way or another about military AIs.
Applications include:
- Underground
- Under dense rainforest canopy where GNSS signals don't reach
- In narrow and deep valleys
- Salt water deeper than 200 mm
- In space, far away from GNSS systems (GNSSes work in space)
Source: I may have wandered through Trimble Nav Ltd. once or twice.
There is a very specific problem - the simulation speed problem - that is in the way.
For games RL agents can be trained by running billions of adversarial simulations. Set up a battle between two agents and reward the one that wins, try variations and repeat, and repeat, and repeat. The trick is to manage the search process so as to not waste time on strategy branches that won't get anywhere, but the idea is very simple.
Unfortunately for things like real world conflict the simulations aren't that representative of what really happens, they are also really really really really complex and slow, and so finding wining strategies is a bit hard.
I was suspecting the northern lights were to blame for most of this trouble since the bad performance periods more or less track to high Kp periods, but it seems that it may be man made interference... There are recent reports from planes flying routes over that area about bad GNSS reception, and efforts from NKOM to log conditions with mobile antennas.
It's probably happening already.
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?
Yes.
> What would a startup need to make this work as a business?
Extensive contacts in the submarine navigation ecosystem and several decades of deep knowledge of highly complex, highly classified, related navigation systems that this product would need to interoperate with.
This tech is not a magic locator machine on its own, it's a component that improves one small but important part of a very large and complex locator system and locator ecosystem.
If the startup has that sort of contact list and experience, it's probably not a startup, it is most likely a division of one of a very small number of very large defense contractors.
(And for those who might argue it's not just for submarines, if the startup has the relevant contacts in the submarine navigation ecosystem, it probably also has the relevant contacts in the other equally classified navigation ecosystems like for cruise missiles and etc., and the technicals aspects of this particular part of the problem domain will probably be relevant across other platform types, even if the details of submarine vs cruise missile inertial navigation platforms are different.)
