[HN Gopher] Underground fiber optics spy on humans moving above
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Underground fiber optics spy on humans moving above
Author : mardiyah
Score : 149 points
Date : 2021-07-04 13:16 UTC (9 hours ago)
(HTM) web link (www.wired.com)
(TXT) w3m dump (www.wired.com)
| dustfinger wrote:
| > By shining a laser through the fiber optics, the scientists
| could detect vibrations from above ground thanks to the way the
| cable ever so slightly deformed.
|
| > Civil engineers are already using DAS to study soil
| deformation, and biologists are even using offshore fiber optic
| cables to listen in on whales. (Sound propagates as a vibration,
| after all.) "It's just really exploding in terms of the
| applications,"
|
| I wonder if ISPs are using residential fiber as an optical
| microphone [1] array to listen to their customers? If they are
| not, then I could see this as a future threat. I wonder how one
| might inexpensively insulate a fiber-optics cable to prevent
| unwanted eavesdropping.
|
| [1]
| https://www.sciencedirect.com/science/article/abs/pii/092442...
| binbag wrote:
| Photonics engineer here: DAS isn't sensitive or spatially
| accurate enough to eavesdrop like that. Also, fibre is very
| rarely to the home. Normally it's to a connection box just
| outside the property and then co-ax to the modem. Lastly, fibre
| telecoms uses lots of repeaters and switches that DAS can't see
| past (needs optical line of sight).
| dustfinger wrote:
| Thank you for your insight, those are all great points. The
| fiber to my home physically runs through my home to a box
| that is located inside of my home. I didn't realize that most
| people have the box located outside of their home.
| galangalalgol wrote:
| I've had fiber into an apartment and into my current home.
| I don't think it is that unusual.
| jcims wrote:
| Any idea if the fiber being used for DAS is simultaneously
| capable of carrying data, or do they pick a strand that is
| unused?
| binbag wrote:
| There are a few different flavours of physics you can use
| for DAS, and they 'use up' different areas of the spectrum.
| As long as what you want to do for telecoms is using
| completely separate wavelengths (channels or bands) then
| yes you can do both. Most DAS providers and users prefer to
| just use un-used/dark fibres though as it avoids any
| headaches.
| devit wrote:
| At least in some European countries fiber goes to a GPON
| terminal in the apartment and then proceeds via Ethernet
| cable to the home router.
|
| I'd guess the co-ax cable is probably a US-only practice.
| binbag wrote:
| I was speaking from a UK perspective which, as another
| commenter says, is mostly co-ax from a point on the
| pavement. 'Actual' FTTP is coming in now, like HyperOptic,
| starting with apartment blocks where they can get lots of
| customers per one new civil engineering job. Most consumer
| telecoms fibre networks in the UK were laid in the 90s and
| don't go right to the home.
|
| If you're in the lucky situation of having true FTTP, then
| it's still very unlikely such fibre could be used as a
| 'microphone' because of the sensitivity and spatial
| resolution issues. It would also be pretty obvious it was
| being used because it would probably interfere unless they
| were very careful with bands. So don't worry, DAS isn't
| going to be used to listen to your voice. Much easier to do
| that with your phone!
| dcow wrote:
| In the US it's not called fiber if there's coaxial in the
| line. If that were true everybody with a cable modem would
| essentially have fiber.
| jkepler wrote:
| When I lived in Chattanooga back in 2011, the Electric
| Power Board offered fiber to the home with an offer of a
| Gigabyte up and down---hence the original use of Gig city
| for Chattanooga. I think this was even before Google
| showcased fiber to the home (was it in Oklahoma City at
| first? I don't recall)
|
| We had to have a router with a fiber port to connect, then
| Ethernet via cat 5 or WiFi.
| fpoling wrote:
| By the same principle it should be possible to listen to
| reflections of the signal propagating in the Ethernet cable
| that external vibrations introduce. But I guess the noise
| in the cable is much greater and the frequency of the
| signal is like 6 order of magnitude smaller making this
| mostly theoretical.
| stordoff wrote:
| Virgin Media (UK) use coax. There are some FTTP installs
| (with coax to the router), but most, as far as I'm aware,
| use coax for the last leg to the house and from the wall to
| the router.
| trollied wrote:
| I've just had BT FTTP installed, and have a fibre coming
| into the building. They use GPON. It's wired into a modem
| ("Optical Network Terminal") that Openreach provide,
| which then presents the connection via cat5. You then
| plug your router in, which then uses PPPoE to establish
| the connection.
| annoyingnoob wrote:
| I have fiber to my home. It runs from the side of my house
| back to a box at the edge of the park down the street. Inside
| that box its combined with the feeds to all of my neighbors
| into a smaller number of runs back to the CO. On the side of
| my house is a steel utility box that contains an ONT which
| converts the signal into ethernet. The ethernet cable runs to
| the other end of my house where I have a router.
|
| I guess theoretically it could sense when I operate the
| garage door and drive in and out, maybe if I take out the
| trash. But the fiber runs through conduit. And given they way
| the fibers are multiplexed down the street in practice its
| hard to infer much from that fiber.
| seizethegdgap wrote:
| I'm a layman network tech with no college degree and no grasp
| of physics beyond very-high level high school science, but I
| can almost guarantee getting voice audio from a fiber drop on a
| GPON network where the NID is outside or in the basement, and
| using the setup in the paper, is currently impossible. The
| paper you linked seems to require purpose-built hardware on
| either end of the fiber, and for the transmit strand to reflect
| into the receive strand, which is not at all how GPON works.
| dustfinger wrote:
| The paper I linked was also from March 1991. I imagine that
| the technology has changed since then. Here is another
| article on fiber optic microphones designed for operation in
| harsh environments [1]. It is from 1999.
|
| [1] https://ui.adsabs.harvard.edu/abs/1999SPIE.3852..106K/abs
| tra...
| seizethegdgap wrote:
| The abstract on that paper makes it seem like the study
| pertains to medical equipment, not telecommunications.
| dannyw wrote:
| The real world answer is 99% of consumers carry a battery
| powered microphone and GPS beacon with remote telemetry, so
| there's no need.
|
| Some also pay money to put internet connected microphones in
| their house.
| [deleted]
| bombcar wrote:
| ISPs can't get residential fiber to work in many cases, using
| it as a microphone is beyond mass capabilities.
|
| Not to say that if the alphabet boys are interested in you they
| might do something similar (but in that cases there are likely
| cheaper methods).
| gavinheavyside wrote:
| In the mid-90's I briefly worked for a company who built and
| installed security systems using this principle, and it looks
| like they are still going:
| https://www.remsdaq.com/solutions/integrated-security-system...
| peter303 wrote:
| Stanford geophysics was the first university to run a optical
| fiber for studying ambient sound. Now there are dozens of these
| for research.
| peter303 wrote:
| Energy companies like these for collecting data in harsh
| environments (e.g. hot geothermal wells) which would degrade
| conventional electronics quickly.
| argomo wrote:
| Interesting new use for existing tech, somewhat clickbait
| headline. Also, the term is "Jerry-rigged". [Edit: I stand
| corrected.]
| toxik wrote:
| Both are actually fine. https://www.dictionary.com/e/jury-
| rigged-vs-jerry-rigged/
| briefcomment wrote:
| > the technology can't exactly identify a car or person. "You can
| say if it's a car, or if it's a truck, or it's a bike. But you
| cannot say, 'Oh, this is a Nissan Sentra, 2019,'" says Stanford
| University geophysicist Ariel Lellouch, who uses DAS but wasn't
| involved in this study but did peer-review it. "Anonymity of DAS
| is one of the biggest benefits, actually."
|
| Good.
| overspeed wrote:
| With sufficient data, acoustic patterns could be learnt to
| identify the type of vehicle down to its model. You might be
| able tell it is a Sentra but not _whose_ Sentra.
| h4waii wrote:
| I'm sure, like all people have different gait, that an acoustic
| profile can be matched against.
| vlovich123 wrote:
| > But you cannot attribute it to a specific person
|
| Until someone figures out how to do gate analysis from the data
| :).
|
| This is a very cool seismography technique though. Could be using
| fiber while it's "dark" to perform a data gathering use for other
| sciences. Like a trans oceanic cable to get a new picture into
| our oceans with multiple data points.
| cycomanic wrote:
| There was a paper in science [1] this year looking at seismic
| events over a submarine link. The fibre also doesn't need to be
| dark in fact.
|
| [1] https://science.sciencemag.org/content/371/6532/931
| peter303 wrote:
| Besides acoustic waves, fiber measures strain, pressure and
| temperature. One proposed application is to line a water ar oil
| pipeline to quickly locate a leak. Currently pressure sensors
| every few miles. The you have to visually inspect the segment for
| the leak. Harder to do for buried pipelines.
| dylan604 wrote:
| Just look for all of the dead grasses where the spill is
| occurring for oil pipelines or patches of lush grasses compared
| to the other areas for water pipes. Or is that too simplistic?
| Prcmaker wrote:
| That indeed works, but is a time consuming manual process,
| pipes arent always leaking clearly (visually), and that only
| works when a failure has occured. I built a few fibre based
| instruments three or four years ago that could detect and
| gauge changes in the pipe caused by wall thinning (before
| leaks have occured), small leaks (too small to notice soil
| changes) and also fouling. Longevity and robustness of the
| sensors was always an issue though
| doggodaddo78 wrote:
| Aggregating and processing enough fiber data might be able to
| work towards identifying mass, contact patch size and shape,
| position, and velocity.
| sharikous wrote:
| That has been used 8 years ago at least to get info on Hamas
| tunnels across the Gaza-Israel border:
| https://www.timesofisrael.com/how-the-tunnels-in-gaza-are-du...
| fsagx wrote:
| I couldn't find any links, but I remember reading about a
| system (or proposed system) working on this principle from the
| 1980s. It was meant to be deployed in the Fulda Gap region to
| precisely locate moving vehicles.
| eloff wrote:
| That was an interesting read, thanks for sharing.
| Animats wrote:
| This could be a lower-cost way to do the border wall with Mexico
| in isolated areas. Use this to detect activity of interest, then
| dispatch a fast drone.
| cartoonworld wrote:
| Why bother when, aside from the Posse Comitatus Act[0], there
| are already extremely advanced optical and synthetic aperture
| satellites that can discern a license plate on the Earth's
| surface flying around the globe?
|
| Or solar powered, regular-assed Ring doorbells (once they get
| that heat problem fixed). As a side effect, then CBP will be
| subsequently able to find their lost car keys out there.
|
| [0] - https://en.wikipedia.org/wiki/Posse_Comitatus_Act
| jodrellblank wrote:
| I imagine this system wouldn't be defeated by waiting until a
| cloudy day?
| cartoonworld wrote:
| I believe that the synthetic aperture satellites can pierce
| cloudcover, probably with reduced minimum features. I'm not
| privy to any special information about this though, so
| don't _really_ know wtf I 'm on about.
|
| But also consider its the desert, you know?
| mkr-hn wrote:
| Those deserts still have a lot of clouds: https://www.esa
| .int/Applications/Observing_the_Earth/Space_f...
|
| They just don't come together enough for much rain.
| cartoonworld wrote:
| I did not know these ranges. Thank you, that is very
| interesting.
|
| It looks like some do and some don't, proving my
| assumptions rather uninformed. The southern US border
| area looks to range from about 60-25%, distributed more
| towards the high end of the range.
|
| I'm aware of coastal deserts like the Atacama which have
| exceptionally low precipitation but lots of foggy
| conditions, but I don't know of any like that in the US
| areas described.
|
| Regardless, I still imagine that satellite, drone, and
| observation posts are the smart way to create the absurd
| Iron Curtain down there. Not that we should...
| ydlr wrote:
| > then dispatch a fast drone.
|
| To do what, exactly?
| [deleted]
| adolph wrote:
| To zoom and enhance
| suifbwish wrote:
| To feed of course.
| throwaway74370 wrote:
| With lead hopefully
| mads wrote:
| Clearly you havent watched many Hollywood movies.
| Animats wrote:
| That's a policy decision.
| atatatat wrote:
| Spoken like a true defense contractor!
| finiteseries wrote:
| Buried seismic sensors have been used by CBP for years now,
| there's an entire program dedicated to using them specifically
| for detecting tunnels as well.
|
| For detecting persons, it's just an evolution of the existing
| process with the massive camera setups.
|
| Sensed/taped footfalls -> closest CBP station -> agent response
| 71a54xd wrote:
| It's still so cool to know that in high security buildings it's
| common to run fiber optic comms cable inside of pipes carrying
| natural gas. Seems like that would largely take care of the
| potential for seismic eavesdropping or wiretapping haha.
| jozvolskyef wrote:
| > Because the speed of light is a known quantity, the Penn State
| researchers could shine a laser through a single fiber optic
| strand and measure vibrations at different lengths of the cable
| by calculating the time it took the scattered light to travel.
| The technique is known in geoscience as distributed acoustic
| sensing, or DAS.
|
| It turns out Marauder's Map was enabled by an underground array
| of optical cables.
| oivey wrote:
| In the electrical world, this is called time domain
| reflectometry.
| jleahy wrote:
| In the optical world we call it OTDR (optical time domain
| reflectometry). What an imaginative bunch we are /s.
|
| You can get a tiny box to do it, to find fiber breaks and bad
| splices.
| Prcmaker wrote:
| There's also OFDR now, frequency based. My understanding of
| it is pretty hand-wavey, but it's a lot more sensitive.
| canadianfella wrote:
| > pretty hand-wavey
|
| What do you mean?
| shadowgovt wrote:
| "hand-wavey" refers to (in this context) an understanding
| that is missing a lot of detail. The term refers to the
| notion that if someone asks you to explain a specific
| piece of the theory, you'd have to respond with
| "enhhhhh...." and a wave of your hand
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