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I remember that too. Maybe this? https://en.m.wikipedia.org/wiki/Gravity_Probe_B
Thats cool! but not that.. the one I an thinking of used the device for course correction over vast distances
Basically floating gyros, pretty common design for IMUs.
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HackerNews amazes me with how for nearly any topic there will be deep expertise in the thread. Thank you for sharing
But then it also usually impresses me with how people think companies haven’t thought of and tried the things they thought of in reading the article and thinking about it for a few minutes.
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GPS is trivial to jam. Any exotic IMU has huge defense implications. Being able to miniaturize it would be a big deal.
Civilian GPS. Milspec encrypted FHSS or whatever are they using not so much unless you flood the whole spectrum.
There are physical restrictions on transmitter aerials which make really wide FHSS impossibly difficult. Especially from a satellite. So GPS still transmits on the same standard 5 frequencies, with some special codings.
The antijamming features work a little differently. If you know a random code sequence you can use various digital noise reduction techniques to improve the SNR and help punch a signal through noise.
But if you blanket blast the transmitter frequencies and their associated components with noise, you're still going to have an effective jammer. It will just have a smaller effective range.
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But then it also usually impresses me with how people think companies haven’t thought of and tried the things they thought of in reading the article and thinking about it for a few minutes.
But sometimes they haven't thought of "it". These forums have an interesting kind of collective intelligence. People commenting here rarely (if ever) have full knowledge of the specifics of the particular instance of the topic at hand, but often have very deep knowledge of the associated theory. In my experience, if you take any 10 people and form a team or company to make some product, they won't have anywhere near…
These are code words I almost never use. I'm no Gary Larson [0].
But someday scientists will discover that they were plum fools for dropping the advancing momentum in vacuum science as badly as they did when solid-state electronics needed to be quickly developed & adopted.
[0] https://i.pinimg.com/originals/98/ed/7a/98ed7ae52758dbb4a645...
https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2F...
The innovation here appear to be the chamber. (caveat: I still need to read the paper). A few thoughts follow. They are going for a UHV***, probably Still a lot of other work to do though. I see a table full of optics to make the MOT*. Also see a pair of anti-Helmholtz coils for the magnetic field. They could maybe replace those coils (which probably drive a few amps) with permanent magnets (assuming they don't need…
> Quantum sensors for PNT use atomic accelerometers or gyroscopes There is one fundamental problem with using any sensors for global positioning: a stationary frame of reference is indistinguishable from the one moving with a constant speed on a straight (actually geodesic [2]) line (inertial frame of reference, general principle of relativity [1]). So accelerometers and gyros indeed can give you accurate orientation…
Actually, they constantly accumulate uncertainty; no change in motion required.
I would think camera-based navigation would be fairly successful at this point. We can easily store large amounts of image and terrain data, and deep learning based image recognition systems are quite powerful. I would think that by limiting your image search space based on your likely position would make the problem even easier to solve. Terrain based navigation is certainly nothing new(1950s?), so there is probably…
> I would think camera-based navigation would be fairly successful at this point. We can easily store large amounts of image and terrain data, and deep learning based image recognition systems are quite powerful. Aside from the fact that the amount of data required for that would be orders of magnitudes larger than you can reasonably store, that wouldn't work at all in areas with little terrain features like deserts…
https://en.wikipedia.org/wiki/TERCOM
Here's a modern take on it: https://www.youtube.com/watch?v=U5Kr0YI3sec
I would think camera-based navigation would be fairly successful at this point. We can easily store large amounts of image and terrain data, and deep learning based image recognition systems are quite powerful. I would think that by limiting your image search space based on your likely position would make the problem even easier to solve. Terrain based navigation is certainly nothing new(1950s?), so there is probably…
> I would think camera-based navigation would be fairly successful at this point. We can easily store large amounts of image and terrain data, and deep learning based image recognition systems are quite powerful. Aside from the fact that the amount of data required for that would be orders of magnitudes larger than you can reasonably store, that wouldn't work at all in areas with little terrain features like deserts…
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> Quantum sensors for PNT use atomic accelerometers or gyroscopes There is one fundamental problem with using any sensors for global positioning: a stationary frame of reference is indistinguishable from the one moving with a constant speed on a straight (actually geodesic [2]) line (inertial frame of reference, general principle of relativity [1]). So accelerometers and gyros indeed can give you accurate orientation…
> they will inevitably accumulate uncertainty for long eventless movements Actually, they constantly accumulate uncertainty; no change in motion required.
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I'm literally experiencing GPS jamming when I'm driving my car near president palace. Like one second I'm moving on road and next second I'm jumping to random places few hundred meters away until I passed long enough. Navigator sometimes goes crazy because of that. So at least civilian GPS is possible to jam.
Well the US Govt is the “owner” of the protocol, they must be able to dos something about it.
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> I would think camera-based navigation would be fairly successful at this point. We can easily store large amounts of image and terrain data, and deep learning based image recognition systems are quite powerful. Aside from the fact that the amount of data required for that would be orders of magnitudes larger than you can reasonably store, that wouldn't work at all in areas with little terrain features like deserts…
Don't look down. Look up. That's been a navigation standard for years. Funnily enough replaced by GPS. https://airandspace.si.edu/collection-objects/astro-tracker-... That doesn't really work in a sub though. Also compasses (especially of the 3D variety) can be a great help.
