
Magnetometers based on diamonds will make navigation easier - prostoalex
https://www.economist.com/science-and-technology/2020/07/18/magnetometers-based-on-diamonds-will-make-navigation-easier
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bb88
> And, crucially for military applications (and unlike GPS-based systems), it
> is unjammable by the enemy.

So while there is not such thing as a magnetic laser, there is a laser that
can create a strong magnetic field.

[https://physicsworld.com/a/radiation-friction-could-make-
hug...](https://physicsworld.com/a/radiation-friction-could-make-huge-
magnetic-fields-with-
lasers/#:~:text=Huge%20magnetic%20fields%20can%20be,role%20in%20generating%20the%20field).

~~~
qserasera
> Our calculations suggest that at least a power of several petawatts is
> needed

Good to know

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Animats
How stable is the earth's magnetic field at that level of detail? There's
enough movement of the magnetic poles right now that new compass correction
charts have to be issued every year or so. Will you need to constantly update
your magnetic maps?

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twarge
Magnetic navigation is totally real and seems to work great.

Diamond magnetometers might not be a great fit for this application. They
require a powerful laser, RF, and are presently huge and impractical. Also,
they are just terrible at accuracy and drift like crazy. Finally - and this is
the thing I really can't get - they require a giant magnetic field to operate.
If your magnetometer has a giant magnet bolted to it, you would expect it to
basically measure drift in that magnet. Diamond magnetometer people will jump
out of the woodwork now, but I haven't seen published high quality data that
says otherwise. Would love to be proved wrong.

Diamond magnetometers are great at being a magnetic microscope since they have
really high density of measurement sites and you can stick it right up next to
an object of interest.

~~~
082349872349872
Drifting like crazy might not be such an issue if one is looking for an AC
signal, such as could be produced by 130m x 13m metal objects moving against
the stationary background.

Huge and impractical sounds like SQuIDs might still be preferable. LN2 is a
byproduct, so it's cheap.

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exabrial
[https://archive.is/5zdJw](https://archive.is/5zdJw)

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maddyboo
> And, crucially for military applications (and unlike GPS-based systems), it
> is unjammable by the enemy.

Is it entirely infeasible for an adversary to disrupt the local magnetic field
enough to interfere with the readings?

~~~
amerine
Based purely in my layman understanding of magnetism, you’d need quite a
disturbance and that same energy would likely not make the rest of any
electronics happy.

~~~
throwaway0a5e
Also give away your position.

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meatmanek
A lot of overlap, but some other details in this Air Force press release from
May: [https://afresearchlab.com/news/air-force-investigates-
using-...](https://afresearchlab.com/news/air-force-investigates-using-
quantum-materials-in-new-navigation-tool/)

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eximius
> so accurate that it might supersede GPS for aerial navigation

Very cool! I wonder if:

1\. the device can be made small enough for consumer use (i.e., phones, smart
watches, etc)

2\. how much data it needs to pinpoint its location. i.e., it might be
suitable in aviation because it can collect a larger amount of data by virtue
of... you know... goin' fast.

~~~
twarge
1\. No, anyway, your phone would have to be engineered to be non-magnetic to
the same level that you wish to make measurements. 2\. Yes, faster is better.
Flying lower is also more specific if you have a sufficiently good magnetic
map.

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mehrdadn
How do compasses work on aircraft? Don't the (varying across space/time?)
magnetic fields from everything on the aircraft overwhelm whatever tiny
variation there is from Earth's surface?

~~~
intc
In aircrafts it's common to use navigation instruments based on gyroscopes.
See:

* [https://en.wikipedia.org/wiki/Gyroscope](https://en.wikipedia.org/wiki/Gyroscope) * [https://www.experimentalaircraft.info/articles/aircraft-gyro...](https://www.experimentalaircraft.info/articles/aircraft-gyroscopic-principles.php)

~~~
mehrdadn
Thanks but I'm confused, how is that relevant to the article?

~~~
kjeetgill
You asked > How do compasses work on aircraft?

So the parent responded with gyroscope based navigation. Perhaps you'd meant
to ask

> How would these compasses work on an aircraft?

*Edited

~~~
pezezin
A compass and a gyroscope are two very different devices.

The former measures the Earth magnetic field, which is an external magnitude
independent of your craft or movement.

The later measures your rate of rotation, which is an internal magnitude. Even
the best gyro will have an small amount of noise and drift, so you need some
external reference to periodically correct it. Also, because they measure an
speed, to get your orientation you need to integrate the measures over time,
which amplifies the noise.

In reality you usually combine both with an accelerometer and a GPS.

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mc32
If this is basically comparing readings to a map of the Earth's magnetic
field, couldn’t they use lidar and a lidar topo map? (I think cruise missiles
used some type of map for navigation too).

~~~
vardump
Lidar's range is measured in hundreds of meters. That might be a bit limiting
for flight. Radar could be used, but you might not want to have a "hey all,
I'm here!"-beacon for military purposes.

You could of course use cameras, pointing either up (stellar navigation) or
down, but that's not going to work all the time.

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renox
I cannot help but remember the time when I got lost during scuba diving
because my new torch was metallic enough that my compass gave bad direction..

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civil_engineer
So there may be a use for diamonds beyond industrial cutting.

