The Many Methods of Communicating with Submarines(hackaday.com)
hackaday.com
The Many Methods of Communicating with Submarines
https://hackaday.com/2020/07/15/the-many-methods-of-communicating-with-submarines/
80 comments
> FLTSATCOM 7 and FLTSATCOM 8 have been used for repeating UHF Satcom transmissions by unauthorized radio users particularly in Brazil, including criminals, illegal loggers, truckers and individuals located in remote areas.
I wonder how much disruption they're causing...
I wonder how much disruption they're causing...
To some degree one can guess some parameters by reverse engineering the list of dual-use technologies:
https://news.ycombinator.com/item?id=23548220
(with my experiences, I see far more submarine detection than communication, but those differently geeky may have better luck.)
(with my experiences, I see far more submarine detection than communication, but those differently geeky may have better luck.)
My favorite attempt to get the Department of Defense to pay for physics research is a paper that suggests building a muon storage ring and using that to generate a beam of neutrinos to communicate with submarines[1].
The physical principals are pretty sound. We do already generate neutrino beams, like at Fermilab[2]. And we do have the ability to detect neutrinos in water, optically as ANTARES[3] does, or acoustically, as SAUND[4] demonstrated.
There are some serious engineering challenges to building a muon storage ring, which is why we don't have any. If we could build them, we could build a muon collider. Muon colliders would be great. Muons are elementary particles, and don't have all the garbage inside that a proton does, and so you'd get very clean signals out of such a collider, unlike the LHC. And since muons are much heavier than electrons, it's easier to get them to very high energies without losing a lot of power to synchrotron radiation.
[1] https://arxiv.org/abs/0909.4554 [2] https://www.fnal.gov/pub/science/particle-physics/experiment... [3] https://antares.in2p3.fr/Overview/index.html [4] http://saund.stanford.edu/saund1/
The physical principals are pretty sound. We do already generate neutrino beams, like at Fermilab[2]. And we do have the ability to detect neutrinos in water, optically as ANTARES[3] does, or acoustically, as SAUND[4] demonstrated.
There are some serious engineering challenges to building a muon storage ring, which is why we don't have any. If we could build them, we could build a muon collider. Muon colliders would be great. Muons are elementary particles, and don't have all the garbage inside that a proton does, and so you'd get very clean signals out of such a collider, unlike the LHC. And since muons are much heavier than electrons, it's easier to get them to very high energies without losing a lot of power to synchrotron radiation.
[1] https://arxiv.org/abs/0909.4554 [2] https://www.fnal.gov/pub/science/particle-physics/experiment... [3] https://antares.in2p3.fr/Overview/index.html [4] http://saund.stanford.edu/saund1/
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I've often wondered about the feasbility of a private firm doing something similar to dominate the HFT scene by getting a massive lead on information from the opposite end of the globe.
Things that improve HFT sadden me because I don't really see the net benefit to mankind. I see someone else's share of the pie getting smaller, someone's gets bigger and the rest of us remain starving.
If one firm develops this their competitors look to do it. You end up with huge investment in the science behind it with everyone trying to do it with higher throughput, lower latency and lower build / run costs than their competitors.
Maybe two decades in the future this becomes a defacto communication technology.
Maybe two decades in the future this becomes a defacto communication technology.
I like your optimism
There are marginal benefits outside of HFT. Mostly, the spread in markets (difference between sell price and buy price) shrinks because of HFT.
Hence people who want to make financial transactions have less friction. In order to interpret this as a global positive, you need to see a more efficient financial system as better.
The story there is usually that a more efficient allocation of capital allows for the most growth, pulling more of the world out of poverty.
(I fully think HFT is good for financial world, less certain on the financial world being better for the wider world)
Hence people who want to make financial transactions have less friction. In order to interpret this as a global positive, you need to see a more efficient financial system as better.
The story there is usually that a more efficient allocation of capital allows for the most growth, pulling more of the world out of poverty.
(I fully think HFT is good for financial world, less certain on the financial world being better for the wider world)
I think you might lose for two reasons:
- Conventional RF systems can function with very low latency. The signal processing chain for radiation detection systems is comparatively large, and can require correlation (or anti-correlation) and significant noise reduction or signal separation to construct a useful signal.
- It requires an unbelievable capital investment for low bandwidth. You need a large time advantage to make your PnL on the few names this would support compared to microwaves and other conventional means.
- Conventional RF systems can function with very low latency. The signal processing chain for radiation detection systems is comparatively large, and can require correlation (or anti-correlation) and significant noise reduction or signal separation to construct a useful signal.
- It requires an unbelievable capital investment for low bandwidth. You need a large time advantage to make your PnL on the few names this would support compared to microwaves and other conventional means.
As somebody else points out the bandwidth isn't a major issue. You can have two opposing strategies and use a single bit to toggle between them.
Put enough behind those strategies and you're making millions a day.
Until your competitors notice and refuse to trade with you or do the same.
Put enough behind those strategies and you're making millions a day.
Until your competitors notice and refuse to trade with you or do the same.
Sorry, this doesn't sound realistic (I work for a major HFT).
Do you have evidence that someone net a billion in a year making a market on a single name?
This seems to ignore that the effective bandwidth could be so low that the latency is greater than conventional transmission systems like RF. Since scintillation radiation detectors are highly stochastic compared to semiconductor RF receivers, I think it's probable it would take too long to receive the bit with sufficient confidence.
Scintillation detectors don't work like a solid state detector and have worse time characteristics.
Do you have evidence that someone net a billion in a year making a market on a single name?
This seems to ignore that the effective bandwidth could be so low that the latency is greater than conventional transmission systems like RF. Since scintillation radiation detectors are highly stochastic compared to semiconductor RF receivers, I think it's probable it would take too long to receive the bit with sufficient confidence.
Scintillation detectors don't work like a solid state detector and have worse time characteristics.
It doesn't need to be a single name. You can select the best target based on expected volatility/volume - for example around announcements. As long as both ends are synchronised ahead of time (which can be done over traditional networks).
The other chain (https://news.ycombinator.com/item?id=23903796) suggested 100 bits per second with a 5% error rate. With the (major) assumptions on that error rate and that you can modify / detect the beam in realtime that gives you plenty to work with.
Of course there is a massive difference between technically possible vs actually implementable.
The other chain (https://news.ycombinator.com/item?id=23903796) suggested 100 bits per second with a 5% error rate. With the (major) assumptions on that error rate and that you can modify / detect the beam in realtime that gives you plenty to work with.
Of course there is a massive difference between technically possible vs actually implementable.
Show me a backtest with a switching rate this low, on any name you can arb between the NYSE/CME/... and JPX with this 7ms advantage and I would acknowledge this is implementable if the PnL and vols justify the opportunity cost.
It’s a very cool idea but I’m skeptical that the market structure supports it.
It’s a very cool idea but I’m skeptical that the market structure supports it.
They would dominate indeed, but potentially at the detriment of Neutrino research detector sensitivity world-wide.
Avoid the pesky curvature of the Earth's surface by going directly along a chord through the mantle rather than along a great circle?
Using https://planetcalc.com/7725/ and https://planetcalc.com/73/ I just concluded that the straight-line chord distance between Tokyo and San Francisco is 1552 km whereas the great-circle distance is 8270 km. (Neither of these is very precise because it's unclear where in each city you should measure from, and unclear whether either calculator uses data about the irregularity of the Earth's curvature.)
It does make a noticeable difference for HFT applications, I guess: 1552 km/c is about 5 ms while 8270 km/c is about 28 ms. (The neutrinos might do better in another way because I guess light in a fiber doesn't directly follow the curve of the fiber itself, since it's getting repeatedly reflected off of the inside surface of the glass.)
Using https://planetcalc.com/7725/ and https://planetcalc.com/73/ I just concluded that the straight-line chord distance between Tokyo and San Francisco is 1552 km whereas the great-circle distance is 8270 km. (Neither of these is very precise because it's unclear where in each city you should measure from, and unclear whether either calculator uses data about the irregularity of the Earth's curvature.)
It does make a noticeable difference for HFT applications, I guess: 1552 km/c is about 5 ms while 8270 km/c is about 28 ms. (The neutrinos might do better in another way because I guess light in a fiber doesn't directly follow the curve of the fiber itself, since it's getting repeatedly reflected off of the inside surface of the glass.)
Speed of light in a fiber is slower than the speed of light in a vacuum, so it's the straight line speed of light versus the great circle speed of light / index of refraction. So you're looking at somewhere north of 35 milliseconds (because the fiber is NOT great circle, and repeaters and routers will add little snips of time every time they touch the signal).
But can you decode a neutrino signal in real time?
But can you decode a neutrino signal in real time?
Pardon my ignorance, but what would a neutrino signal look like? Can’t it be pulsed on/off like an electron beam - does it have a wavelength/frequency like a photon?
Pulses, yes.
Making a neutrino beam is remarkably convoluted. https://en.wikipedia.org/wiki/Accelerator_neutrino
>The process of the muon neutrino or muon antineutrino beam production consists of the following steps[1][2]:
>Acceleration of a primary proton beam in a particle accelerator.
>Proton beam collision with a fixed target. In such a collision secondary particles, mainly pions and kaons, are produced.
>Focusing, by a set of magnetic horns, the secondary particles with a selected charge: positive to produce the muon neutrino beam, negative to produce the muon anti-neutrino beam.
>Decay of the secondary particles in flight in a long (of the order of hundreds meters) decay tunnel. Charged pions decay[3] in more than 99.98% into a muon and the corresponding neutrino according to the principle of preserving electric charge and lepton number...
There's several different places in this chain where you could modulate the beam by turning various magnets on or off. Probably not in the proton accelerator.
Unfortunately, "long string of expensive experimental equipment" means "not efficient". From the paper:
>A neutrino source delivering muons at a rate of 10^14 s^−1 with an energy of 150 GeV would require about 4 MW in proton beam power and 2.4 MW acceleration power, which for a 10% electrical efficiency translates into a total power consumption of roughly 65 MW.
Yow. Something like ten times more power than the NuMI neutrino beam. He concludes this transmitter could do something like 100 bits/s to a stationary detector string anchored at the ocean bed. Deeper the better, for shielding against cosmic rays and solar radiation. Would be tough to put a neutrino detector close enough to a financial hub and still get useful bandwidth.
Making a neutrino beam is remarkably convoluted. https://en.wikipedia.org/wiki/Accelerator_neutrino
>The process of the muon neutrino or muon antineutrino beam production consists of the following steps[1][2]:
>Acceleration of a primary proton beam in a particle accelerator.
>Proton beam collision with a fixed target. In such a collision secondary particles, mainly pions and kaons, are produced.
>Focusing, by a set of magnetic horns, the secondary particles with a selected charge: positive to produce the muon neutrino beam, negative to produce the muon anti-neutrino beam.
>Decay of the secondary particles in flight in a long (of the order of hundreds meters) decay tunnel. Charged pions decay[3] in more than 99.98% into a muon and the corresponding neutrino according to the principle of preserving electric charge and lepton number...
There's several different places in this chain where you could modulate the beam by turning various magnets on or off. Probably not in the proton accelerator.
Unfortunately, "long string of expensive experimental equipment" means "not efficient". From the paper:
>A neutrino source delivering muons at a rate of 10^14 s^−1 with an energy of 150 GeV would require about 4 MW in proton beam power and 2.4 MW acceleration power, which for a 10% electrical efficiency translates into a total power consumption of roughly 65 MW.
Yow. Something like ten times more power than the NuMI neutrino beam. He concludes this transmitter could do something like 100 bits/s to a stationary detector string anchored at the ocean bed. Deeper the better, for shielding against cosmic rays and solar radiation. Would be tough to put a neutrino detector close enough to a financial hub and still get useful bandwidth.
65 MW is only $6M/year at the cheapest available electricity prices. Even less if you turn it off at night or when markets aren't as volatile.
100 bits/sec is plenty to make lots of money... If you consider 100 bits/sec is 1 bit per 10 milliseconds, with say a 5% bit error rate (can't do error correction without introducing delay).
Each end of the connection can make two candidate investment strategies based on globally available data. The 'bit' decides which strategy to go for.
Easy money for anyone who can turn the science into reality... Easy money that will dry up as soon as a few other people start doing the same...
100 bits/sec is plenty to make lots of money... If you consider 100 bits/sec is 1 bit per 10 milliseconds, with say a 5% bit error rate (can't do error correction without introducing delay).
Each end of the connection can make two candidate investment strategies based on globally available data. The 'bit' decides which strategy to go for.
Easy money for anyone who can turn the science into reality... Easy money that will dry up as soon as a few other people start doing the same...
> can't do error correction without introducing delay
Hamming Codes don’t, unless I’m missing something?
Hamming Codes don’t, unless I’m missing something?
In hamming codes, the correction can only be done when an entire block has been received.
With a block length more than 1, you therefore introduce latency of 10s of milliseconds.
With a block length of 1, a hamming code doesn't do any error correction.
Hamming codes would let you access the uncorrected data immediately, and do error correction later (after the block length has passed), but at that point you have already used it to make trading decisions, so it's too late.
With a block length more than 1, you therefore introduce latency of 10s of milliseconds.
With a block length of 1, a hamming code doesn't do any error correction.
Hamming codes would let you access the uncorrected data immediately, and do error correction later (after the block length has passed), but at that point you have already used it to make trading decisions, so it's too late.
NuMI cost $139 million to construct, including the detectors. It was driven by the Tevatron, a proton accelerator 2km across that itself cost $197 million to build in 1991. 150 GeV particle accelerators are not cheap, and are going to be impossible to build secretly.
If everyone knows you have a phone to the future, finding counterparties is going to be hard. Who's going to take the other side of a trade you know you're going to lose?
If everyone knows you have a phone to the future, finding counterparties is going to be hard. Who's going to take the other side of a trade you know you're going to lose?
Are those numbers correct? In the worst case, the chord would be the diameter and the great circle would be half the circumference, so the ratio would be (pi.d/2)/d = pi/2 = 1.57.
For fun the cos rule can be used to derive a general formula for the ratio of great circle to chord, given the angle (theta) in radians subtended at the centre of the Earth:
theta / sqrt( 2-2.cos(theta) )
where: theta = (great circle distance) / radius
(Assuming I haven't mucked up my algebra.)
--
Not sure why my comment is rendering in italics. No emphasis is meant. Figured it out, it was the asterisk I used for a multiplication symbol.
For fun the cos rule can be used to derive a general formula for the ratio of great circle to chord, given the angle (theta) in radians subtended at the centre of the Earth:
theta / sqrt( 2-2.cos(theta) )
where: theta = (great circle distance) / radius
(Assuming I haven't mucked up my algebra.)
--
Not sure why my comment is rendering in italics. No emphasis is meant. Figured it out, it was the asterisk I used for a multiplication symbol.
Thank you for the sanity check. It looks like the web site has a bug!
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The app you linked has some issues with data entry. If you re-enter the minutes field for SF, it will give a straight line distance of about 7800km, instead of the 1500km you listed. As another commenter pointed out the worse case is ratio is about 1.5, so I'm guessing either it's totally buggy or 7800km is the correct one.
Light in fiber travels at about 2/3 s of the speed of light in a vacuum. Not because of bouncing (the fiber creates a waveguide) but just because it is inside glass.
This different speed of light is what gives glass its refractive index, which makes it optically useful.
This different speed of light is what gives glass its refractive index, which makes it optically useful.
Thanks, I feel like I've just experienced Feynman's complaint about his Brazilian students not applying their knowledge of the concept of "index of refraction" to an actual physical object. That is, I didn't think about how the whole idea of the index of refraction of a material is directly derived from the different speed of light in that material.
I'm still confused because I thought I had learned that fiber optical cables work by total internal reflection, in which the light inside is repeatedly reflected by the surface of the fiber. Is this an overly simplistic view for thinking about the path that the light will follow in the fiber?
I'm still confused because I thought I had learned that fiber optical cables work by total internal reflection, in which the light inside is repeatedly reflected by the surface of the fiber. Is this an overly simplistic view for thinking about the path that the light will follow in the fiber?
It is a somewhat simplistic view because light isn't just a particle bouncing off walls, its a wave. What happens is that the fiber creates a 'waveguide'. This will gently curve the wavefront around the fiber.
I barely understand this myself. But the way I imagine this is essentially as a water wave running through a trough.
Lets consider a simple sinusoidal wave originating at one end of the trough. Lets call a wavefront any line across the trough that follows the peak of a wave (really it can be any fixed phase, but peaks are nicer to visualize). What happens to these wavefronts as time goes on? They bend around the corners. Essentially the water just in front of the wavefront is going to be pushed up next, and when this happens has a lot more to do with distance from the current wavefront than whether the actual water particles are bouncing off the wall or not.
My explanation of wavefronts moving forward doesn't quite explain why the wavefront 'rotates' in a curved waveguide. I would guess something about path interference being different on the inside of a corner than the outside. Someone who actually studied this stuff probably knows a lot better.
I barely understand this myself. But the way I imagine this is essentially as a water wave running through a trough.
Lets consider a simple sinusoidal wave originating at one end of the trough. Lets call a wavefront any line across the trough that follows the peak of a wave (really it can be any fixed phase, but peaks are nicer to visualize). What happens to these wavefronts as time goes on? They bend around the corners. Essentially the water just in front of the wavefront is going to be pushed up next, and when this happens has a lot more to do with distance from the current wavefront than whether the actual water particles are bouncing off the wall or not.
My explanation of wavefronts moving forward doesn't quite explain why the wavefront 'rotates' in a curved waveguide. I would guess something about path interference being different on the inside of a corner than the outside. Someone who actually studied this stuff probably knows a lot better.
Neutrino detection is very slow, it is averaging signal over several hours to transfer a few bytes. Useless for HFT.
Wait then why are you implying that they’re pulling a fast one on the DoD when you make it seem like a neutrino beam is a legitimate method of submarine communication?
Also in the plus column you get to call it 'tightbeam communication' and make a bunch of sci fi people very happy.
> If we could build them, we could build a muon collider. Muon colliders would be great.
Making muons easy to make/keep will get us closer to a legit cold fusion reactor as a result.
https://en.wikipedia.org/wiki/Muon-catalyzed_fusion#Viabilit...
Making muons easy to make/keep will get us closer to a legit cold fusion reactor as a result.
https://en.wikipedia.org/wiki/Muon-catalyzed_fusion#Viabilit...
If you like this kind of stuff checkout "Blind Man's Bluff: The Untold Story Of American Submarine Espionage"
There are so many fascinating details about submarine operations that are now unclassified (and makes you guess about what things are like that are still hidden). From communications to the underground listening stations to attempting (and succeeding) in wire-tapping soviet communication cables, to attempting to lift a wrecked foreign submarine right off the ocean floor.
It's an amazing read and very well written.
There are so many fascinating details about submarine operations that are now unclassified (and makes you guess about what things are like that are still hidden). From communications to the underground listening stations to attempting (and succeeding) in wire-tapping soviet communication cables, to attempting to lift a wrecked foreign submarine right off the ocean floor.
It's an amazing read and very well written.
The audiobook has some nice extra commentary as well.
That book blew the cover off missions that hadn’t been known to the public at all, so it was a bit controversial at release - the commentary touches on all that.
Red November and The Taking of K129 are also great reads along these lines.
That book blew the cover off missions that hadn’t been known to the public at all, so it was a bit controversial at release - the commentary touches on all that.
Red November and The Taking of K129 are also great reads along these lines.
I think you mean 'The hunt for Red October'
I loved the audiobook, but somehow I missed the controversy part. Thanks for the recommendations!
Thanks! I just downloaded the Kindle book.
I worked on the Eaton AIL CVLF radio receiver, which was the one of the first digital radio receivers done in the late 1980s. Because the frequencies used to communicate with subs were around 19 kHz, the CPUs of the time were just fast enough to do the signal processing. We used the Fairchild 9445 which was essentially a Data General "Nova 4" on a chip.
This receiver was used to receive launch commands. It received teletype data that was printed on a Model 29 Teletype. The encryption keys and the key generator used on this project were compromised by the Walkers, a family of spies (See https://news.usni.org/2014/09/02/john-walker-spy-ring-u-s-na... )
The Submarines dragged a wire antenna that was used to receive the VLF radio signals, that were transmitted from several megawatt sites within the US and beyond.
This receiver was used to receive launch commands. It received teletype data that was printed on a Model 29 Teletype. The encryption keys and the key generator used on this project were compromised by the Walkers, a family of spies (See https://news.usni.org/2014/09/02/john-walker-spy-ring-u-s-na... )
The Submarines dragged a wire antenna that was used to receive the VLF radio signals, that were transmitted from several megawatt sites within the US and beyond.
What, nothing about NATO's JANUS?
> JANUS performance has so far been evaluated by many collaborating partners at centre frequencies from 900 Hz - 60 kHz and over distances up to 28 kilometers in waters all over the world.
> JANUS packet and bit error rates have been computed as functions of the signal to the noise ratio (SNR) and time spread over periods extending from hours to months. Signal correlation times have been computed and long-term experiments by CMRE(external link) in 2008 and 2009 have helped quantify robustness during variable environmental conditions.
* http://www.januswiki.com/tiki-index.php?page=About+Janus
Toolkits available under GPLv3.
* https://www.popularmechanics.com/technology/infrastructure/a...
* https://spectrum.ieee.org/tech-talk/telecom/wireless/nato-de...
* https://robohub.org/janus-creates-a-new-era-for-digital-unde...
> JANUS performance has so far been evaluated by many collaborating partners at centre frequencies from 900 Hz - 60 kHz and over distances up to 28 kilometers in waters all over the world.
> JANUS packet and bit error rates have been computed as functions of the signal to the noise ratio (SNR) and time spread over periods extending from hours to months. Signal correlation times have been computed and long-term experiments by CMRE(external link) in 2008 and 2009 have helped quantify robustness during variable environmental conditions.
* http://www.januswiki.com/tiki-index.php?page=About+Janus
Toolkits available under GPLv3.
* https://www.popularmechanics.com/technology/infrastructure/a...
* https://spectrum.ieee.org/tech-talk/telecom/wireless/nato-de...
* https://robohub.org/janus-creates-a-new-era-for-digital-unde...
JANUS looks great on paper, but is pretty restrictive for doing anything useful in real life.
At the standard frequency bands they've chosen (9440-13600 Hz), with the type of coding scheme they use FH-BFSK, the bandwidth is too limited (4KHz -> ) to do anything except service discovery.
Having said that, I agree, it should have been mentioned.
At the standard frequency bands they've chosen (9440-13600 Hz), with the type of coding scheme they use FH-BFSK, the bandwidth is too limited (4KHz -> ) to do anything except service discovery.
Having said that, I agree, it should have been mentioned.
> JANUS looks great on paper, but is pretty restrictive for doing anything useful in real life.
Were they going for reliability rather than bandwidth?
Are there any alternative 'underwater modem/codec' standards?
Were they going for reliability rather than bandwidth?
Are there any alternative 'underwater modem/codec' standards?
You can actually hear some forms of Gertrude through the hull!
I slept with my head right near the hull, and when we did a certain kind of op where it was in use, you could faintly hear what sounded like a home modem.
I slept with my head right near the hull, and when we did a certain kind of op where it was in use, you could faintly hear what sounded like a home modem.
You can hear it in the movie The Abyss as well, since Cameron is a stickler for accuracy.
> “It sometimes seems hard to believe that we humans have managed to explore so little of what we have so much of: the seas.”
Apparently fewer people have been to the bottom of the Mariana trench (between 11 and 12,732 km away from you) than to the moon (about 400,000 km away from you).
Apparently fewer people have been to the bottom of the Mariana trench (between 11 and 12,732 km away from you) than to the moon (about 400,000 km away from you).
Visiting the bottom of the Mariana Tench might be feasible for some people here.
Apparently there are three slots available on a first-come-first-serve basis, for $750,000.
https://www.cnn.com/travel/article/marianas-trench-challenge...
Climbing Everest used to be a bucket list item for me, but not anymore after I hear how bad it's gotten over the years.
Going into space seems more feasible for me than the trench, only $250,000.
Apparently there are three slots available on a first-come-first-serve basis, for $750,000.
https://www.cnn.com/travel/article/marianas-trench-challenge...
Climbing Everest used to be a bucket list item for me, but not anymore after I hear how bad it's gotten over the years.
Going into space seems more feasible for me than the trench, only $250,000.
Yeah, Mt Everest... nobody goes there anymore, it’s too crowded ;-)
I happened to be in Guam in 2012 and in some dodgy dive bar (...) ran into the crew that took James Cameron down to Challenger Deep, only the second manned descent ever. Didn’t believe them a word until I saw my couch surfing host dancing with Cameron.
I happened to be in Guam in 2012 and in some dodgy dive bar (...) ran into the crew that took James Cameron down to Challenger Deep, only the second manned descent ever. Didn’t believe them a word until I saw my couch surfing host dancing with Cameron.
> Yeah, Mt Everest... nobody goes there anymore, it’s too crowded ;-)
Mt. Everest is the kind of place where that could be literally true (though I don't think it is, yet), if you count corpses as part the crowding...
Mt. Everest is the kind of place where that could be literally true (though I don't think it is, yet), if you count corpses as part the crowding...
While I do feel like it is still an appropriate joke to make in the sense that it sounds ridiculous to say you aren't interested in Mt Everest because its too crowded, sadly it seems we have already reached that point in time - https://www.washingtonpost.com/world/2019/05/24/mount-everes...
You can try Biography/Realization. Not too crowded, near Céüse. https://en.wikipedia.org/wiki/Realization_(climb)
But about a dozen already climbed it.
I recall an X-Files episode where a woman was affected by the transmission of a ULF or ELF antenna and it was making her crazy. Was a fun episode
Here it is https://en.wikipedia.org/wiki/Drive_(The_X-Files)
Here it is https://en.wikipedia.org/wiki/Drive_(The_X-Files)
Ah yes: the other Vince Gilligan TV show starring Bryan Cranston.
>"While the high frequency (HF: 3 MHz to 30 MHz) and low frequency (LF: 30 kHz to 300 kHz) bands are perfectly capable of reaching across the globe thanks to ionospheric refraction, the high conductivity of seawater rapidly attenuates signals in these bands.
Dialing down the spectrum a bit, the very low frequency (VLF: 3 kHz to 30 kHz) band starts to exhibit decent penetration of seawater, down to a depth of perhaps 20 meters."
[...]
>"Going even further down the spectrum, signals in the extremely low frequency (ELF: 3 Hz to 30 Hz) band are capable of penetrating 120 meters of seawater"
Submarines aside, this is tremendously interesting how specific mediums (in this case, salt water) either act as transducers or attenuators for different radio frequencies.
Now, when a radio frequency is influenced by some form of matter (in this case, salt water, and at higher frequencies, attenuation), it might be because the matter and the radio frequency are somehow related.
In other words, perhaps future scientists will discover that the molecules of water are resonating at a frequency which is a much higher harmonic than the radio waves that they block. And/or perhaps their frequency is somehow related to the much lower frequency radio waves that they conduct.
See, it's sort of like any attenuator can act as a conductor (or vice versa), but the frequency or set of frequencies used makes the determination as to whether the medium in question is going to attenuate or conduct...
Compare this concept to resistors in electronics.
They resist standard DC... but what about AC at a certain frequency, or pulsed DC at a certain frequency?
The higher the frequency (to a certain point when space becomes conductive and thus dissipative with respect to the circuit), the more a resistor should become a conductor...
Also, observation: The reason why distance is lost (in seawater, but also other mediums) when higher frequencies are used, is typically because power is converted into frequency, which then, in the case of a standard radio wave, expands into space as a sphere, that is, it's a inverse-square-law power loss over space.
Compare radio waves to lasers; lasers do not lose power in accord with the inverse-square-law over space...
Dialing down the spectrum a bit, the very low frequency (VLF: 3 kHz to 30 kHz) band starts to exhibit decent penetration of seawater, down to a depth of perhaps 20 meters."
[...]
>"Going even further down the spectrum, signals in the extremely low frequency (ELF: 3 Hz to 30 Hz) band are capable of penetrating 120 meters of seawater"
Submarines aside, this is tremendously interesting how specific mediums (in this case, salt water) either act as transducers or attenuators for different radio frequencies.
Now, when a radio frequency is influenced by some form of matter (in this case, salt water, and at higher frequencies, attenuation), it might be because the matter and the radio frequency are somehow related.
In other words, perhaps future scientists will discover that the molecules of water are resonating at a frequency which is a much higher harmonic than the radio waves that they block. And/or perhaps their frequency is somehow related to the much lower frequency radio waves that they conduct.
See, it's sort of like any attenuator can act as a conductor (or vice versa), but the frequency or set of frequencies used makes the determination as to whether the medium in question is going to attenuate or conduct...
Compare this concept to resistors in electronics.
They resist standard DC... but what about AC at a certain frequency, or pulsed DC at a certain frequency?
The higher the frequency (to a certain point when space becomes conductive and thus dissipative with respect to the circuit), the more a resistor should become a conductor...
Also, observation: The reason why distance is lost (in seawater, but also other mediums) when higher frequencies are used, is typically because power is converted into frequency, which then, in the case of a standard radio wave, expands into space as a sphere, that is, it's a inverse-square-law power loss over space.
Compare radio waves to lasers; lasers do not lose power in accord with the inverse-square-law over space...
>They resist standard DC... but what about AC at a certain frequency, or pulsed DC at a certain frequency?
Um.. yes. This is actually exactly how you model coupling capacitors when analyzing circuits. You use them to connect two nodes. Apply DC and no current flows through once the capacitor is charged. Apply AC and the signal is transmitted to the other side. The strength of the transmitted signal is dependent on frequency and of course whatever else you have connected to the circuit.
Um.. yes. This is actually exactly how you model coupling capacitors when analyzing circuits. You use them to connect two nodes. Apply DC and no current flows through once the capacitor is charged. Apply AC and the signal is transmitted to the other side. The strength of the transmitted signal is dependent on frequency and of course whatever else you have connected to the circuit.
I remember researching this in 2008 and I thought satellite based lasers were already in common usage (sending signal to specific known surface location and also receiving from that location using the surface of the ocean as the medium that the sub and satellite read.
This was a while ago so no links maybe I’m misremembering.
This was a while ago so no links maybe I’m misremembering.
Also learned about submarine to satellite direct communications with lasers in a 33c3 video at: https://youtu.be/P4Qk88IpND0?t=32m8s
Source: https://twitter.com/kdeldycke/status/830035138805428224
Source: https://twitter.com/kdeldycke/status/830035138805428224
they do this with directional encrypted radio. what would be the advantage of doing it with a laser other than 'friggin' laser'?
The USSR used buoys extensively during the cold war. Here's a former naval officer describing the sonar based system:
https://www.youtube.com/watch?v=Eb6e_-HvBzw
https://www.youtube.com/watch?v=Eb6e_-HvBzw
I recently stumbled on this channel. It’s amazing to watch him “twitch stream” analyzing an underwater recording to pull out all sorts of interesting insights while only using a consumer, general purpose audio software.
You can do some pretty effective low bitrate critical satcom stuff with a buoy and molniya orbit satellites. The Russian military has been launching molniya orbit narrowband comms satellites periodically for the past 45 years. They're used for ground, air and naval C4I purposes.
With the long satellite dwell time over high latitude and Arctic regions, a submarine in the arctic ocean could surface a buoy that has a radome in its top, containing a small yagi-uda antenna with a fat oval gain pattern aimed straight up at the sky.
With the long satellite dwell time over high latitude and Arctic regions, a submarine in the arctic ocean could surface a buoy that has a radome in its top, containing a small yagi-uda antenna with a fat oval gain pattern aimed straight up at the sky.
I just did a Ctrl-f on this comments page, and on the article for "iridium", and I'm surprised nobody has mentioned the disposable/expendable iridium buoys yet.
They absolutely exist and come in several varieties. These are not as big a secret as they were 15 years ago. The USN was the first user of such things, but other NATO countries have also purchased and deployed them, or developed their own models.
They absolutely exist and come in several varieties. These are not as big a secret as they were 15 years ago. The USN was the first user of such things, but other NATO countries have also purchased and deployed them, or developed their own models.
I love reading about stuff like this!
I had 2 questions perpetually on my mind:
1) The article doesn't go into physical sonic wave communication, like ultrasonic I suppose. Did that ever have applications for submarine comms?
2) I always wonder whether like in the movies, submarines actually have or ever use the audible ping. Of course, it gives away one's position instantly, but does such a ping capability even exist still, on modern submarines?
I had 2 questions perpetually on my mind:
1) The article doesn't go into physical sonic wave communication, like ultrasonic I suppose. Did that ever have applications for submarine comms?
2) I always wonder whether like in the movies, submarines actually have or ever use the audible ping. Of course, it gives away one's position instantly, but does such a ping capability even exist still, on modern submarines?
I was a sonar tech on a nuclear submarine 20 years ago. I don't recall hearing about any ultrasonic applications. As for the "audible ping": Yes, such a capability exists, and it is very much like the movies. It is rarely used for the reason you mentioned.
Re: #2, that is active sonar, which is for useful for locating objects that are silent, e.g., rocks.[1] It also is very loud and disruptive for whales and dolphins.[2]
[1] https://oceanservice.noaa.gov/facts/sonar.html
[2] https://skeptoid.com/episodes/4236
[1] https://oceanservice.noaa.gov/facts/sonar.html
[2] https://skeptoid.com/episodes/4236
Ah of course, the issue several years ago when the Navy's testing was causing whale / dolphin strandings...
1) Yes, it’s nicknamed “Gertrude”.
2) Yes, every tactical platform that hunts subs has an active sonar capability of some kind. (Hull mounted, towed, dipping, sonobuoys, ...) When the ambient noise floor exceeds the target sub’s noise, you need that option.
2) Yes, every tactical platform that hunts subs has an active sonar capability of some kind. (Hull mounted, towed, dipping, sonobuoys, ...) When the ambient noise floor exceeds the target sub’s noise, you need that option.
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> The 228,000 ocean-dwelling species that we know about represents about ten percent of the estimated total aquatic species.
I don't buy it. The idea that the deep ocean is full of all this life we haven't plundered yet seems like a fantasy.
I don't buy it. The idea that the deep ocean is full of all this life we haven't plundered yet seems like a fantasy.
They usually make these types of estimates by looking at the rate of new species discovery, and assuming it will asymptotically approach zero.
Do you have any idea just how vast the seas are? Think about it for a while. Consider that we mostly bob about on top and that is much bigger area compared to dry land. Now allow that it keeps on moving and drops away to up to 11 Km deep. Our senses are nearly useless in this alien world. 10% is just an educated guess and may be woefully low.
>The idea that the deep ocean is full of all this life we haven't plundered yet seems like a fantasy.
It's quite simple, they count the total number of species in the ocean and then use the number of species we know about to work out the percentage.
It's quite simple, they count the total number of species in the ocean and then use the number of species we know about to work out the percentage.
"Species" includes arthropods, other invertebrates, and everything else all the way down to single-cellular organisms. And there is an incredible abundance of variety among those forms of life. I doubt we have even catalogued 10% of all species of beetles, never mind of all oceanic life.
https://en.wikipedia.org/wiki/Fleet_Satellite_Communications...
https://en.wikipedia.org/wiki/UFO_(satellite)
https://en.wikipedia.org/wiki/Milstar
https://en.wikipedia.org/wiki/Global_Broadcast_Service
https://en.wikipedia.org/wiki/Defense_Satellite_Communicatio...
https://en.wikipedia.org/wiki/Advanced_Extremely_High_Freque...
https://en.wikipedia.org/wiki/Minimum_Essential_Emergency_Co...
The interesting aspects of how USN submarines access these systems doesn't appear to be openly available.