[HN Gopher] New laser could cram GPS alternative into a shoebox
___________________________________________________________________
New laser could cram GPS alternative into a shoebox
Author : fofoz
Score : 70 points
Date : 2024-09-24 07:44 UTC (4 days ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| master_crab wrote:
| Sadly, the first applications of this will most likely be
| military.
| ceejayoz wrote:
| This will absolutely go in missiles to handle GPS jamming and
| submarines where satellite signals are unavailable, yes.
|
| It'll be nice if they can get it small enough for a phone,
| though.
| reliablereason wrote:
| I would assume that the refrigerator sized ones are
| definitely already in submarines.
| zardo wrote:
| Maybe, but this isn't the only way to build a high
| performance accelerometer.
| nordsieck wrote:
| > This will absolutely go in missiles to handle GPS jamming
|
| Depending on when the tech is available, preventing GPS
| jamming of drones is probably much more urgent in Ukraine.
| ceejayoz wrote:
| Yes, but until they're autonomous the drones are still
| heavily subject to jamming of their radio controls. This
| won't fix that.
|
| HIMARS, on the other hand, will enjoy the improvements.
| KennyBlanken wrote:
| "Until"?
|
| They've been in use for years now in that war. The Shahed
| drone, for example, was used by Russia. About two years
| ago Ukraine was using autonomous drones to down Shahed
| drones.
|
| AI targeting came out in the Gulf war, friend. 35 years
| ago, Tomahawks could use rudimentary AI to match
| preprogrammed terrain profile and target imagery to get
| more precise targeting.
| ceejayoz wrote:
| > The Shahed drone, for example, was used by Russia.
|
| The Shaeed is really just a rather shitty cruise missile.
|
| https://en.wikipedia.org/wiki/HESA_Shahed_136 "No cameras
| or short-range sensors were noted in 2022."
|
| > Tomahawks could use rudimentary AI to match
| preprogrammed terrain profile and target imagery to get
| more precise targeting.
|
| Key word: preprogrammed, and similarly a cruise missile.
|
| It's the FPV drones chasing down people in trenches that
| require real-time video transmission to control.
| talldayo wrote:
| The Shahed drone can't use it's INS system to communicate
| with a ground operator or reprogram itself. As the other
| comment says, it's basically a glorified cruise missile
| that has the autonomy of a Roomba. Disabling a Shahed
| with another drone _may_ have happened, but it 's
| certainly not the primary threat to the Shahed when
| compared to CIWS or SAMs.
|
| AI targeting was debuted in the Patriot missile system,
| which does technically field the required elements of a
| hands-off kill chain. But TERCOM is not AI nor was it
| debuted in the 90s with the TLAM. The original _BLOCK-I_
| variants of the Tomohawk (and many versions released
| afterwards) were no more autonomous than the Shahed-136.
| aledalgrande wrote:
| Yeah it would be awesome to finally have accurate positioning
| in between highrises on the phone, gps sucks for that.
| vlovich123 wrote:
| That's literally what's funding this research
| imoverclocked wrote:
| That could be the point of sentiment around this tech. Most
| funded development is done out of military R&D instead of
| science/consumer/art purposes. Everything else ends up
| benefiting eventually but it would be nice if we didn't only
| create things for war and then later repurpose them for
| everything else.
| KennyBlanken wrote:
| More specifically, nuclear arms, where the budget is "there is
| no budget." Just the inertial guidance system of a 90's-era
| ICBM cost over six figures per missile. The ability to
| precisely place a missile without any external navigation
| (except for stars.)
|
| Once it gets cheap enough, it'll probably go into cruise
| missiles; it could eliminate or reduce the need for terrain
| contour matching, which requires radar transmission.
|
| I'm not 100% certain but I believe when MEMS accelerometers
| first came out, the better ones were subject to arms controls
| because of fears they could be used in missiles.
| littlestymaar wrote:
| Nuclear arms doesn't need as much accuracy as other weapons
| though: when using a cruise missile or a glide bomb with a
| few hundreds of kilograms of explosives, you need metric
| precision to get the military effect, when the payload is a
| 100kt bomb, then 100m is accurate enough.
|
| Unlike other bombs it must absolutely be 100% resilient to
| any kind of spoofing though, for obvious reasons, hence GNSS
| is a nonstarter for those when they are the default guidance
| system for other weapons (with backups, for cruise missile).
| dingaling wrote:
| > when the payload is a 100kt bomb, then 100m is accurate
| enough
|
| Not accurate enough for counterforce. When a missile silo
| lid can withstand 600 atmospheres of overpressure, "close
| enough" isn't good enough.
| KennyBlanken wrote:
| My point was that nuclear missile development gets a blank
| check and I cited the over-six-figure intertial guidance
| units in 80's and 90's era missiles as an example of this.
|
| I'm not sure what point you're trying to make here?
|
| Accuracy is incredibly important because you don't put a
| nuke somewhere to kill people; you put it there to destroy
| infrastructure. More specifically nuclear missile silos,
| and bomb shelters (well, the people inside them.)
|
| Reducing the CEP means you can use a smaller nuclear yield
| to get the job done, which is preferable for a number of
| reasons, including politics, but also allowing for more
| targets in a strike.
|
| The very latest US ICBMs are suspected of having sub-100m
| CEP. CEP for ICBMs is "bad" enough that it is typical for
| planners to figure three warheads per target, but accuracy
| is rumored to be getting good enough where that is no
| longer necessary.
| dgroshev wrote:
| > you don't put a nuke somewhere to kill people; you put
| it there to destroy infrastructure. More specifically
| nuclear missile silos, and bomb shelters (well, the
| people inside them.)
|
| It depends.
|
| "Counter-force" strikes aim to destroy the ability to
| respond or attack with nuclear weapons, not
| infrastructure per se. So that's just silos, warhead
| storage sites, submarines in port, airfields, etc. The US
| is doctrinally counter-force for about half a century.
| This doctrine is also reflected in technological choices:
| lower yields and higher precision mean lower fallout,
| collateral damage, and fratricide when hunting for silos,
| but aren't that useful for city busting.
|
| "Counter-value" strikes are pure destruction of cities
| and killing of people. Russia seems to have this doctrine
| [1]. This is a very inflexible doctrine, because you
| can't credibly threaten to execute a counter-value attack
| on the US over things that don't seem to be worth a
| response in kind (like a defeat in Ukraine). It's much
| cheaper though.
|
| > The very latest US ICBMs are suspected of having
| sub-100m CEP
|
| Apparently the precision is good enough for photos like
| the one on page 23 here
| https://www.osti.gov/servlets/purl/1557069
|
| [1]: At least strategically. There is a hybrid strategy
| of targeting military-related infrastructure, which
| Russia seems to have adopted for less-than-strategic
| forces according to recent leaks https://www.ft.com/conte
| nt/237e1e55-401d-4eeb-875b-03fe68f81... .
| roywiggins wrote:
| It makes a difference for hard targets, see the new nuclear
| "super-fuzes."
|
| It can take several warheads to destroy a missile silo with
| high probability, because even landing a little off-target
| can spare the silo. Greater precision means it takes
| substantially fewer.
|
| https://thebulletin.org/2017/03/how-us-nuclear-force-
| moderni...
| jfengel wrote:
| In Russia's case, there does appear to be "no budget". The
| weapons were intended as a last resort, and so they are a
| great target for diverting maintenance funds.
|
| It's not quite so bad as "we are certain that they will not
| successfully launch any nukes" and so they're still being
| treated with caution. But the US keeps upping what it allows
| Ukraine to do as it loses its fear of World War III.
|
| As it applies to the US... yeah, the sky is the limit for
| military spending.
| dgroshev wrote:
| There is no fear of WWIII, that's part media invention,
| part political excuse, part useful idiots. A "World War"
| requires an opponent worthy of a world-wide conflict, and
| Russia is anything but, being stuck in Ukraine for three
| years and losing most of its army in the process.
| Conventionally, Russia is no match for NATO, with enough
| political will it'd be a Desert Storm-like curb stomp. The
| only way it's not is the US abandoning NATO, then it can be
| quite painful, but even then Russian economy is no match
| for the EU.
|
| As for nuclear weapons, they are practically useless.
| Anything but strategic use would have little impact on the
| battlefield, but will immediately alienate China and India.
| They have their own border conflicts and do NOT want the
| nuclear taboo to be broken, and they are holding the leash,
| being the only economic and technological lifeline Russia
| has. A strike against the US would be suicidal for obvious
| reasons.
|
| Also, notice how Putin and his officials _talk_ about
| nuclear use a lot, but there is still zero evidence of any
| _action_ (such as dispersal of road-based ICBMs or 12th
| GUMO taking warheads out of storage). Rhetoric is cheap and
| not credible.
|
| The only real fear of escalation here is "horizontal"
| escalation: Russia stirring shit elsewhere. Advanced anti-
| ship missiles to Houthis, handing nuclear technology to
| North Koreans or submarine technology to China, that kind
| of thing. But that's already seem to be happening, and
| there isn't much more that Russia can do.
| JumpCrisscross wrote:
| > _will immediately alienate China and India_
|
| To drive this home, India and China have a moderately
| high probability of engaging in armed conflict with a
| nuclear power in the next decades. (India with Pakistan
| and China, China with America.)
|
| They do _not_ want tactical nukes to be normalised in
| prelude to those conflicts.
| aguaviva wrote:
| _There is no fear of WWIII, that 's part media invention,
| part political excuse, part useful idiots._
|
| Not true at all. The risk may be overstated by some, but
| it's a perfectly possible outcome that must be
| considered.[0]
|
| _A "World War" requires an opponent worthy of a world-
| wide conflict, and Russia is anything but_
|
| Also simply not true. It just requires one side to start
| using nukes, which can also happen entirely by accident
| (and has come close to happening multiple times, even
| without a multi-year and incredibly nasty hot proxy
| conflict on the ground between two of the planet's
| largest mutual adversaries).
|
| _As for nuclear weapons, they are practically useless._
|
| True of course, but it doesn't matter. What matters is
| that certain people might start to _think_ that they 're
| useful and/or their only choice. Which gets into the fact
| that we can't assume these people are acting rationally.
|
| _Also, notice how Putin and his officials talk about
| nuclear use a lot, but there is still zero evidence of
| any action_
|
| Right, but that can change at any time. It doesn't even
| have to be a tactical battlefield strike (which of course
| would be useless, and their people know it). For example,
| once their backs are pushed against the wall with
| sufficient firmness, Putin or his successors might start
| to think that a demonstrative high-altitude detonation
| over an ocean somewhere might be a pretty neat idea.
| Especially if they've reached a point where they have
| nothing more to lose, and have a reasonable fear of being
| outright killed sooner or later if the current situation
| on the ground starts to move strongly and rapidly against
| them.
|
| [0] - https://news.ycombinator.com/item?id=41525830
| dgroshev wrote:
| I don't think there is any conceivable scenario in which
| Russia using nuclear weapons would lead to anything
| resembling "World War", except Russia launching a
| counter-value strike against continental US, which is
| just not happening. A high-altitude detonation is not a
| "World War".
|
| Russia is a China's client state at this point, and China
| is very interested in keeping nukes taboo. They are so
| worried their own army is only allowed melee weapons in
| border skirmishes with India. There is no way a
| demonstrative breaking of the taboo would not get Putin's
| leash yanked, so even that remote possibility (that has
| nothing to do with WW3) is extremely improbable and would
| only hasten Russia's defeat. Unless, of course, our
| politicians use it as an excuse to abandon Ukraine.
|
| Also, no one is "pushing Russia's back against the wall"
| in Ukraine, there are no M1A2s speeding to Moscow. Russia
| understands it perfectly well, too, denuding their
| borders with NATO to throw more soldiers into the meat
| grinder.
|
| > the fact that we can't assume these people are acting
| rationally
|
| I think this meme is largely a cop-out. A person just
| doesn't get to be a leader of a country by acting
| irrationally. They might interpret things differently or
| have different priorities, they might even put on an act
| of irrational buffoonery, but it's different from being
| "irrational". However, to see the rationality of their
| actions requires putting yourself in theirs shoes, which
| is uncomfortable and/or requires a deeper understanding,
| so it's easier to just write their behaviour as
| "irrational".
|
| Putin is perfectly rational. The empty threats are
| working (as evidenced by this thread), there is no risk
| of a strategic exchange (because the actual signalling on
| the ground is one of business as usual), and Western
| politicians are successfully convincing their voters that
| they drag their feet because WW3, not because actually
| stopping the war (eg deploying a NATO peace keeping
| force) would incur a substantially higher domestic cost.
|
| We don't really talk about potential North Korean
| aggression in WW3 terms, do we? We shouldn't do that in
| Russian case either.
| horstbort wrote:
| Thankfully, the same measurement technique can be used to
| measure e.g. gravitational fields, and there are already
| devices available on the market which surpass classical
| gravimeters in accuracy and precision. There are also satellite
| missions in the planning to map Earth's gravitational field
| with atom interferometry.
| mhb wrote:
| It's only sad if you are a fan of inaccurate munitions and
| collateral damage.
| hi-v-rocknroll wrote:
| This is truism applicable to the vast majority of technologies.
| Space was once also a rival mother of invention.
|
| If quantum INS can soon take out more Russian ammo dumps in
| spectacular fashion, then bring on improvements to lasers.
| swayvil wrote:
| An ultra sensitive motion sensor. Intriguing.
|
| Could one derive the Earth's rotation? The motion of the solar
| system?
|
| By watching vibrations could it be a microphone?
| thfuran wrote:
| You don't need anything nearly so fancy for a laser microphone.
| swayvil wrote:
| Still want one.
|
| _And this vector right here.... that 's the milky way's
| orbit about the greater magellanic cloud..._
| jacobp100 wrote:
| No because velocity only makes sense as relative to something
| else. There's no 'fixed points' in the universe
|
| This device will track acceleration rather than velocity
| roywiggins wrote:
| Points on the Earth's surface are experiencing an
| acceleration- after all, after 12 hours their velocity has
| changed direction by ~180 degrees.
|
| You can detect Earth's rotation with a sufficiently large
| pendulum[0] or a good gyroscope. Something with enough
| inertia will tend to refuse to rotate with the planet, which
| lets you compare the two and infer the absolute rotational
| speed of the planet.
|
| https://en.wikipedia.org/wiki/Foucault_pendulum
| swayvil wrote:
| I figure that all motion is curved because all motion is on
| space bent by gravity or whatever. So motion always
| involves some acceleration vectors.
|
| Is that... assful?
| cooljacob204 wrote:
| For the first two questions I wouldn't think so because it
| detects acceleration. But I also only have a high school level
| of physics knowledge so maybe I'm wrong.
| roywiggins wrote:
| Anything rotating is experiencing acceleration, you can tell
| whether your merry-go-round is spinning or not with your eyes
| closed: that's the acceleration.
| Majromax wrote:
| > Could one derive the Earth's rotation?
|
| Yes, existing gyroscopes are sensitive enough for that. In
| 1966, one of the first Soviet attempts to launch the Soyuz
| failed on the pad because the guidance system remained active
| after a scrubbed launch attempt. After a couple of hours, the
| Earth had rotated enough such that the guidance system thought
| it was off-course, triggering the still-armed launch escape
| system.
|
| > The motion of the solar system?
|
| This system, probably not. This _class_ of system at lab scale,
| maybe eventually. It seems that the galaxy 's gravitational
| acceleration on the solar system is on the order of 10^-10 m/s
| (https://www.sciencedaily.com/releases/2020/12/201203133906.h..
| .), so about 10 pico-g. The article says that cold atom
| interferometers have current sensitivities in the nano-g range
| but could still potentially improve.
|
| > By watching vibrations could it be a microphone?
|
| With that kind of sensitivity, making it _not_ be a microphone
| is probably the harder task. However, the sensitivity doesn 't
| necessarily make it a good microphone, since detecting a small
| signal is useless if the signal-to-noise ratio is too low.
| red75prime wrote:
| > that the galaxy's gravitational acceleration on the solar
| system is on the order of 10^-10 m/s
|
| A free falling accelerometer (that is an accelerometer that
| moves along a spacetime geodesic) will detect no
| acceleration. And the solar system "free-falls". I don't see
| how we can detect that.
| KennyBlanken wrote:
| > Could one derive the Earth's rotation? The motion of the
| solar system?
|
| It's not a motion sensor; it's an acceleration sensor. That's
| an important distinction because the primary problem with IMUs
| is that they work of changes in velocity, and error in those
| measurements slowly accumulate - so they almost always need
| external references to correct for accumulated drift.
| bee_rider wrote:
| We've had other discussions of these sort of quantum compass
| ideas, see
|
| https://news.ycombinator.com/item?id=40692333
|
| for example.
|
| I can never quite wrap my head around it or figure out if they
| are all the same idea, or what, and what exactly the idea is.
|
| In particular, the article soften describe something that "could
| replace GPS." But then they start taking about compasses, and
| things that sound a lot like IMUs. Integrating accelerations is
| well known as a bad way of keeping track of position over longer
| timescales due to catastrophic cancellation. A more accurate IMU
| might let you do it for a little longer, but eventually you need
| an absolute reference point to correct your drift.
|
| But then, sometimes there are references to making very careful
| measurements of the change in the gravitational field. So maybe
| those could act as landmarks or something?
|
| I wish there was an article for people who, like, had _a_ control
| theory or signal processing class, but it was too early in the
| morning and not very interesting.
| gmrple wrote:
| Gravity map matching is an approach that can provide absolute
| references, the general problem there is that gravity maps are
| not good enough.
| bee_rider wrote:
| They also vary over time or something, right? So even a more
| precise measurement device, to get better gravity maps,
| doesn't solve the problem... maybe? This is all based on
| half-remembered other comments.
| ricksunny wrote:
| So I would like to learn more about gravity map matching.
| I've seen offhand references to it in context of placing an
| ICBM on target (can't find ref now) but that's it. I
| imagine it is, (or was for long enough to make info sparse)
| a classified piece of know-how.
| kurthr wrote:
| There's also the tides, and variations in the tides with 2nd
| and 3rd order effects on gravity. Absolute references based
| on variable references is ugly!
| rcxdude wrote:
| Only when you're on the ground in the first place. Otherwise,
| you have a circular problem: past a certain point your IMU
| needs a gravity map to remain accurate, else the drift from
| variations in gravity is larger than the drift in your
| sensor. And you need to know where you are and how you're
| moving to measure gravity.
| Arch485 wrote:
| My understanding is that by using "the magic of quantum",
| accelerations can be measured with 0 error (for practical
| purposes), so it's an incredibly accurate dead reckoning
| positioning system. In that way, it's "GPS, but better" because
| you can't be jammed or lose signal. It would also work under
| water or under ground.
| horstbort wrote:
| That's the gist of it, yes. The big advantage atom
| interferometers have over classical IMUs is that they do not
| need to be recalibrated every so often. They are thus often
| called "drift free". That still means that you need to
| compare your position with a reference after a certain time,
| but the position uncertainty is much lower and only
| determined by the error accumulating from integration, not
| due to the instrument itself degrading over time and
| introducing systematic errors. The reason here is not really
| "quantum magic" but rather the fact that the reference for
| the measurement is a laser beam which can be controlled with
| remarkable precision and accuracy.
| actinium226 wrote:
| From the article
|
| > Motion sensors in wearable devices are usually sensitive to
| accelerations in the range of [milli-gs]. Bigger, more
| expensive accelerometers ... on the order of [0.1 mill-gs]
|
| > More accurate than either of these mobile accelerometers are
| cold-atom interferometers. These currently have sensitivities
| of [nano-gs], with future potential for [femto-gs], Kodigala
| says.
| Animats wrote:
| This used to be mostly a military problem. No longer. GPS is no
| longer reliable enough for civilian aerial navigation in much
| of eastern Europe and the Middle East.[1] _" Most recently, for
| the one-month period from July 15 - August 15, 2024, a total of
| 41,000 flights experienced spoofing. Because modern aircraft
| have incorporated GPS into a large number of aircraft systems,
| the impact of a spoofed GPS signal has had severe and cascading
| effects. These include the FMS, Hybrid IRS, the aircraft clock,
| GPWS, Weather Radar, CPDLC, ADS-B and ADS-C, as well as
| numerous other systems."_ GPS is so low power that spoofing
| signals now take out a large area of service.
|
| [1] https://ops.group/blog/gps-spoofing-final-report/
| MichaelZuo wrote:
| There are many frequent flyers travelling on routes going
| through those regions, dozens of times each in the last year.
|
| And they haven't reported any noticeable issues caused by GPS
| spoofing, at least not that I've heard of.
|
| So I'd be surprised if modern planes are designed such that
| the loss of GPS for an hour or two would cause issues severe
| enough to be noticed by even seasoned travellers.
| aftbit wrote:
| Not to be a jerk, but you would be wrong. GPS spoofing is a
| growing problem in commercial aviation. So far it has not
| led to any fatalities, but it has led to a significant
| number of system malfunctions which degrade the safety
| features available to pilots.
|
| One example that made the rounds on social media a few
| months back was a crew flying above 30,000 ft receiving
| "Terrain - Pull Up!" advisories. They ignored them, because
| there is no terrain on earth at 30k ft. If that had
| happened at a lower altitude, they would have likely had to
| do a terrain escape maneuver, which would definitely be
| felt by passengers, though it would likely not introduce a
| lot of additional safety risk.
|
| The real risk comes when pilots begin to doubt that their
| safety systems are working correctly and thus ignore true
| warnings. Or when a bungled GPS leads pilots to fly into
| military airspace and get shot down.
| JumpCrisscross wrote:
| > _Because modern aircraft have incorporated GPS into a large
| number of aircraft systems_
|
| Aviation is slow. It wasn't until recently that GPS-based
| landing approach became common, and even then you're double
| checking with ground radar. No commercial airliner would use
| IMU--if ground-based radar is not operating or cooperating,
| you get out of that airspace.
| cryptonector wrote:
| Inertial navigation can be paired with GPS (and friends),
| terrain recognition, etc. to keep it accurate, and it can be
| used to detect jamming attacks on GPS. You can even use fairly
| low accuracy IMUs to detect jamming attacks on GPS, so it's
| certainly worth using.
|
| With enough accuracy the frequency at which an IMU needs to be
| recalibrated with GPS or other systems can be low enough that a
| ship need only do it when at port, or a plane need only do it
| when parked or at an airport gate. I.e., at places where
| differential GPS can be available and/or where location can be
| known statically since the location only changes due to
| continental drift (i.e., very slowly).
| ck2 wrote:
| I wonder if we are within a century of having pulsar detection on
| a chip.
|
| Document enough millisecond pulsars and find your position
| anywhere in the galaxy.
|
| When signal reception and computing power get powerful enough,
| put it on your wrist.
| ajuc wrote:
| The main application would obviously be missiles and autonomous
| military drones. If you can use GPS - you should. It's crazy
| cheap and it doesn't accumulate errors over time. But in a war
| GPS can be jammed. This can't.
| 2OEH8eoCRo0 wrote:
| Lot's of Western weapons already combine INS and GPS. I suppose
| this could be a better alternative to INS.
|
| https://en.wikipedia.org/wiki/AGM-158_JASSM
|
| > Guidance system: GPS, INS, IIR
| wood_spirit wrote:
| There was a big cheapening when the military miniaturised
| fast gps so small and cheap it could be put into artillery
| shells. This was very effective when Excalibur and himars
| first arrived in Ukraine.
|
| By the time the small diameter bombs had been married to a
| rocket the Russians had effective and pervasive gps jamming
| and accuracy plummeted.
|
| The older more expensive systems with ins like atacms
| maintained accuracy.
| ajuc wrote:
| There's a Polish guy that volunteered in Ukraine building
| drones, he talked about this.
|
| There are tricks to avoid most of the GPS jamming, long-
| distance drones use them (he said the evolution is crazy
| fast, every 3 months there's new techniques deployed) the
| traditional military systems can't be modified in 3 months
| so they are more vulnurable.
|
| They are constantly changing the video and controlling
| frequencies, there is some AI appearing, a big change was
| flying signal repeaters, there are tethered flying drones
| with rolls of fibre for steering/video that are completely
| invulnurable to jamming. Often they also have cables for
| power, so they can stay in air forever.
|
| But even in the cheapest drones there are ways to deal with
| it. For starters you shield the GPS from the bottom half-
| sphere, and you put 2 GPS receivers at opposite ends of the
| drone and compare the signals. Jammers are closer than
| sattelites, so the difference between the signals sampled 2
| meters apart will be mostly the jamming, and then you can
| remove it.
|
| It's not perfect, but it's good enough for the drones to
| hit the targets most of the time. And they obviously have
| cheap accelerometers, compass etc - which is basically INS,
| just less accurate. So it's sufficient to get by through
| the region with jamming, and to recognize when GPS is
| spoofed.
| IshKebab wrote:
| This _is_ inertial navigation. It 's just much more accurate
| than existing systems.
| hi-v-rocknroll wrote:
| INS incl. LRG has been a thing for decades. The modern
| problem is over-reliance on GPS (military coded and
| commercial). QINS would solve many issues but GNSS is also
| still needed to calibrate the system at least initially (at
| launch) and opportunistically mid-course. The other thing
| that is being fielded, despite its downsides and
| vulnerabilities, is wire guidance a-la TOW.
| cryptonector wrote:
| Commercial airliners and ships badly need this functionality.
| fdfgyu wrote:
| Ships are big, if this were a real problem it would be easy to
| find space for a "lab sized" laser.
|
| ICBM warheads are small. Space in drones and fighter jets is at a
| premium.
|
| This is military.
| bluGill wrote:
| While ships are big, there is a lot they want in them so space
| tends to be limited if the ship wasn't designed to do that.
| Military places the big things and the rest in between
| ttul wrote:
| If Sandia is revealing this, they probably have a secret version
| that is already being loaded into cruise missiles and ICBMs.
| Seeing what's happening over in Ukraine, it has to be clear to
| every military in the world that GPS is no longer of much
| practical use on its own.
| krick wrote:
| So, remembering the exact location once, and then tracking all
| movement with almost absolute precision, thus calculating all
| future locations? Did I get it right?
| actinium226 wrote:
| Basically yes. If you want to get technical about it, it's not
| tracking movement it's tracking acceleration, which you can
| then integrate twice to update position.
| krick wrote:
| Technically, acceleration is movement in an inertial
| system... Anyway, I was wondering for a long time, why
| phones/watched don't attempt to do it (at least, I never saw
| useful results of it). Surely it would be more useful to me
| than nothing, when lost in a labyrinth underground. I always
| assumed, that results are so horrible (close to random) that
| nobody even bothers. But then it doesn't tell me much if
| there is an accelerometer 1000 or 1M times more accurate, in
| a shoe-box or otherwise. Like, how often does it have to re-
| calibrate after all?
|
| Are there any records of how currently available consumer
| devices measure up in this regard?
| mhb wrote:
| After integrating the output twice from current COTS
| accelerometers, position is useless in at most a few
| minutes.
| sahmeepee wrote:
| You might be interested in this app to try it for yourself:
|
| https://github.com/nisargnp/DeadReckoning
|
| I read a paper some time ago which suggested that mobile
| devices are still nowhere near good enough to use this e.g.
| for navigation around a shopping mall.
| kylehotchkiss wrote:
| But like an IMU, doesn't this need occasional calibration with a
| known location source?
| cryptonector wrote:
| Yes, but if it's accurate enough then the frequency of
| recalibration can be kept low enough that inertial navigation
| can be practical.
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