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New laser could cram GPS alternative into a shoebox

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Re: New laser could cram GPS alternative into a shoebox

#91

Post by dgroshev »

aguaviva wrote: post #88
dgroshev wrote: post #85

Earlier quoted context omitted.

> an entirely possible provocation that could shove things in that direction How? What plausible pathway do you see between Russia exploding a nuke over Novaya Zemlya and their suicide by American nuclear response? > A major shift in the ground situation Ukraine's favor (effectively signaling an eventual Russian defeat) could do the trick. I don't understand what trick. Russia directly attacking NATO? They'd get pulv…

Why are you picking the oblique and obviously implausible case of Putin trying to "scare" the West by detonating a device on his own territory (and as far away from his adversaries as possible)? What people are worried about is a low-yield device over the Black Sea or the North Sea, say. The "pathway" is that any deployment of a device will at the very least trigger a suite of necessary countermeasures on both sides…

> a low-yield device over the Black Sea or the North Sea

How is it different? What "panic reactions"? What "panic reaction" can connect a low-yield explosion over Black Sea and a suicidal strategic strike on the continental US?

> I'm just advocating that we observe the cautionary principle here

"The cautionary principle" is only applicable if you disregard hundreds of thousands of killed and maimed Ukrainians, millions of refugees, unknown number of abducted children, and entire cities raised to the ground. Letting a genocide continue for years is not a default safe option.

Again, I invite you to reflect on this exchange: you'd "rather not delve into scenarios", but when weighing what's basically just vibes against very material, prolonged, ongoing suffering of the second largest country in Europe you decide to advocate for vibes. Putin's bullshit has already won and his deterrence succeeded, because you give it enough credibility (whilst refusing to outline a credible scenario) to talk about "WW3" as a real risk worth more than dead and maimed Ukrainians.

Re: New laser could cram GPS alternative into a shoebox

#92

Post by littlestymaar »

roywiggins wrote: post #46
littlestymaar wrote: post #13

Earlier quoted context omitted.

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 th…

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...

I don't really get this argument: if you have a metric precision munition in an ICBM then even an inert warhead is going to be enough to penetrate and destroy due to the kinetic energy coming from the hypersonic nature of the reentry vehicle (and even if kinetic energy itself wasn't sufficient, a conventional payload would be)

Nuclear bombs are useful because you don't need precision to get the effectiveness, but if you have the precision then why would you bother with the consequences of using nukes…

Re: New laser could cram GPS alternative into a shoebox

#93

Post by ck2 »

xandrius wrote: post #89
ck2 wrote: post #15

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.

Problem is always going to be power rather than computation. I still haven't heard of any major breakthrough in the size of our batteries but when that comes we'll be miniaturizing literally anything.

We already have solar self-charging watches, power sources by then will also be micro kinetic generators, room temperature vs body temperature generators, and even pulling power from all the radio signals in the room like 5ghz, etc.

Maybe they will even use some kind of super capacitors instead of batteries.

Re: New laser could cram GPS alternative into a shoebox

#94

Post by roywiggins »

littlestymaar wrote: post #92
roywiggins wrote: post #46

Earlier quoted context omitted.

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...

I don't really get this argument: if you have a metric precision munition in an ICBM then even an inert warhead is going to be enough to penetrate and destroy due to the kinetic energy coming from the hypersonic nature of the reentry vehicle (and even if kinetic energy itself wasn't sufficient, a conventional payload would be) Nuclear bombs are useful because you don't need precision to get the effectiveness, but if…

Not if the silo can withstand a direct hit from anything short of a nuclear bomb going off nearby. ICBMs aren't that precise- or they didn't used to be- and that's why you'd compensate for that with nuclear warheads. Or, alternatively, early ICBMs would have seemed nearly pointless to develop before nuclear weapons existed to put on them.

If a superfuze or a super-IMU means that you can kill one silo with one nuke, that is a huge improvement over the old status quo, where it was assumed to take several, simply because the CEP was larger than the radius at which they can destroy a silo.

If someone does have an conventional ICBM that can reliably take out nuclear silos that would be an even bigger deal.

Of course the US military has been working on conventionally-armed ICBMs: https://en.m.wikipedia.org/wiki/Conventional_Prompt_Strike

Re: New laser could cram GPS alternative into a shoebox

#95

Post by aguaviva »

dgroshev wrote: post #91
aguaviva wrote: post #88

Earlier quoted context omitted.

Why are you picking the oblique and obviously implausible case of Putin trying to "scare" the West by detonating a device on his own territory (and as far away from his adversaries as possible)? What people are worried about is a low-yield device over the Black Sea or the North Sea, say. The "pathway" is that any deployment of a device will at the very least trigger a suite of necessary countermeasures on both sides…

> a low-yield device over the Black Sea or the North Sea How is it different? What "panic reactions"? What "panic reaction" can connect a low-yield explosion over Black Sea and a suicidal strategic strike on the continental US? > I'm just advocating that we observe the cautionary principle here "The cautionary principle" is only applicable if you disregard hundreds of thousands of killed and maimed Ukrainians, millio…

> a low-yield device over the Black Sea or the North Sea

How is it different?

From a detonation deep inside their own territory? You tell me.

a suicidal strategic strike on the continental US?

I never suggested that would be the next step. In fact my words said something entirely different.

For some time now I've been noticing a consistent tendency in your posts to employ straw man techniques. Then we have this:

Letting a genocide continue for years is not a default safe option.

you decide to advocate for vibes

you give it enough credibility (whilst refusing to outline a credible scenario) to talk about "WW3" as a real risk worth more than dead and maimed Ukrainians.

I'm doing absolutely none of those things. Unfortunately the conversation has definitely into unproductive territory, and you seem to be confusing me with other people you're unhappy with. I'm not those people and my energy resources are quite limited. Let's wrap up here and give the topic a rest, please.

Re: New laser could cram GPS alternative into a shoebox

#96

Post by [deleted] »

red75prime wrote: post #44
Majromax wrote: post #12

Earlier quoted context omitted.

> 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…

> 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.

[deleted]

Re: New laser could cram GPS alternative into a shoebox

#97

Post by aftbit »

MichaelZuo wrote: post #83
aftbit wrote: post #69

Earlier quoted context omitted.

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,…

Pilots can be instructed to ignore GPS related warnings and not trust GPS based systems for the one or two hour duration while they are transiting the jammed airspace. Better yet they can be disabled temporarily since presumably the same proof can be shown to the relevant regulators, airline HQ, etc… They aren’t automatons that must obey every single system installed in the plane regardless of how absurd the outputs…

Of course, but these systems are installed and active with the intention of providing a safety barrier. If they are disabled while transiting jammed airspace, then they are not providing that safety barrier at that time, which is itself a vulnerability.

Besides, it is hard to determine when and where jamming will happen, and it can start and stop at any time. Imagine a truck driver trying to bypass their company tracking using a small jammer, and driving down the coastal highway near SFO. Any planes coming in for landing might lose GPS or even worse, get inaccurate results, but only for a moment or two. Is that a problem? It depends on exactly what the plane is doing in that moment and whether everything else is going right.

Re: New laser could cram GPS alternative into a shoebox

#98

Post by amy-petrik-214 »

MichaelZuo wrote: post #83
aftbit wrote: post #69

Earlier quoted context omitted.

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,…

Pilots can be instructed to ignore GPS related warnings and not trust GPS based systems for the one or two hour duration while they are transiting the jammed airspace. Better yet they can be disabled temporarily since presumably the same proof can be shown to the relevant regulators, airline HQ, etc… They aren’t automatons that must obey every single system installed in the plane regardless of how absurd the outputs…

When I was a war pilot this was common practice. Shut off radio. You'd know they were going to mess with you in creative and twisted ways. So much simpler to put it on mute. Usually works best in situations where radio silence is also a mission parameter

Re: New laser could cram GPS alternative into a shoebox

#99

Post by cyberax »

minetest2048 wrote: post #82
cyberax wrote: post #78

Another obvious idea: use mega-constellations. GPS signals can't be signed because the signal bandwidth is limited, a digital signature is going to take hours to get transmitted. But by using something like a Starlink satellite, it's possible to transmit digitally signed timing packets that can't be spoofed.

Galileo open signals are signed: https://www.gsc-europa.eu/galileo/services/galileo-open-serv... and it have the same data throughput as GPS L1

It takes about 5 minutes to transmit a signature, as I understand? The receiver then can try to find the combination of navigation packets that gives the right signature, and recover its position this way.

So yeah, this should solve the spoofing issues for most cases. Low-orbit sats would be able to transmit a signature every millisecond or so, but that's not really necessary.

Re: New laser could cram GPS alternative into a shoebox

#100

Post by ricksunny »

rcxdude wrote: post #73
ricksunny wrote: post #34

Earlier quoted context omitted.

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.

For sufficiently accurate IMUs, like the ones found in ICBMs, you need a gravity map because otherwise the variations in gravity cause your position estimate to drift

That's helpful; so presumably for the same reason that gyrocompasses function (self-aligning vis-a-vis the local gravity vector).

A part of me was subconsciously entertaining that a subsystem of the IMU / INS was actually being used to provide gravimetric navigation (producing a coarse global position update de novo rather than correct for an error-prone open-loop one from an a priori generated gravity map). a la

https://ieeexplore.ieee.org/document/9059124

or

https://www.researchgate.net/publication/343278497_Analysis_...

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