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New laser could cram GPS alternative into a shoebox

spectrum.ieee.org

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Re: New laser could cram GPS alternative into a shoebox

#31

Post by KennyBlanken »

ceejayoz wrote: post #24
nordsieck wrote: post #16

Earlier quoted context omitted.

> 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.

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.

"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.

Re: New laser could cram GPS alternative into a shoebox

#32

Post by bluGill »

fdfgyu wrote: post #30

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.

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

Re: New laser could cram GPS alternative into a shoebox

#33

Post by ajuc »

wood_spirit wrote: post #27
2OEH8eoCRo0 wrote: post #23

Earlier quoted context omitted.

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

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.

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.

Re: New laser could cram GPS alternative into a shoebox

#34

Post by ricksunny »

bee_rider wrote: post #28
gmrple wrote: post #18

Earlier quoted context omitted.

Gravity map matching is an approach that can provide absolute references, the general problem there is that gravity maps are not good enough.

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.

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.

Re: New laser could cram GPS alternative into a shoebox

#35

Post by ceejayoz »

KennyBlanken wrote: post #31
ceejayoz wrote: post #24

Earlier quoted context omitted.

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.

"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.

> 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.

Re: New laser could cram GPS alternative into a shoebox

#36

Post by Arch485 »

bee_rider wrote: post #11

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. In…

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.

Re: New laser could cram GPS alternative into a shoebox

#37

Post by imoverclocked »

vlovich123 wrote: post #6
master_crab wrote: post #2

Sadly, the first applications of this will most likely be military.

That’s literally what’s funding this research

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.

Re: New laser could cram GPS alternative into a shoebox

#38

Post by actinium226 »

bee_rider wrote: post #11

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. In…

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.

Re: New laser could cram GPS alternative into a shoebox

#39

Post by kurthr »

gmrple wrote: post #18
bee_rider wrote: post #11

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. In…

Gravity map matching is an approach that can provide absolute references, the general problem there is that gravity maps are not good enough.

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!

Re: New laser could cram GPS alternative into a shoebox

#40

Post by horstbort »

Arch485 wrote: post #36
bee_rider wrote: post #11

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. In…

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.

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.
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