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Device offers long-distance, low-power underwater communication
- soperj 3y agoI'm guessing this will really be hell for whales.
- deleted 3y ago[deleted]
- Gys 3y ago[flagged]
- RalfWausE 3y ago[flagged]
- outworlder 3y agoNo, the current systems are hell. This is a massive improvement.
- dylan604 3y agoMy natural first reaction is what unknown effect will this have on underwater life? We know other types of sonar have had negative effects. Knowing that, this should be studied and considered when making any new underwater sounding equipment. You don't get to go "we never thought about it" now that we know about it.
- awei 3y agoThis was also my first thought.
- backendanon 3y agoAt 1 million times less power than existing sound transmission systems I'd say it's probably less audio going into the water than a baby whale fart.
- Eduard 3y agothat's -60dB, no? like the reduction from gunshot (140dB) to alarm clock (80dB)... or jet plane take-off (120dB) to normal conversation (60dB). Depending on the actual, absolute values, one-millionth can therefore be still annoying — especially if it is pervasive and omnipresent.
- cogman10 3y agoThe innovation here is to make that unidirectional rather than omnidirectional. So seems reasonable to conclude that even if the beam is gunshot noisy, outside the beam is basically silent.
- nomel 3y agoMaybe I'm not understanding, but isn't this reflecting sound back, generated by something else? It seems the device uses one millionth the power, but the thing stimulating the device uses an unspecified amount, that would increase dramatically with distance. Unfortunately this is an MIT press release, so it will be impossible to understand what's actually going on. Does anyone have a more informative link?
- omniglottal 3y agoThere is no more information, as described in TFA, for reasons of this information having not been discovered yet by the researchers studying the new tech.
- wirelessR 3y agoThe press release links the two publications: - http://www.mit.edu/~fadel/papers/VAB-paper.pdf http://www.mit.edu/~fadel/papers/VAB-paper.pdf - http://www.mit.edu/~fadel/papers/PAB-theory-paper.pdf http://www.mit.edu/~fadel/papers/PAB-theory-paper.pdf
- nomel 3y ago> ... fix the input electrical power to 150 W ... The 20 dB DI transducers push the uplink decoding range up to several kilometers. That probably is close to a baby whale fart, but I doubt competing systems are running at 150,000,000 W, as the above comment suggests. In their test to get 60m, they used 1.8W. 1.8 MW seems unlikely, for the same distance, with competing tech. There's a fundamental misunderstanding of what's going on here. But, that's to be expected, with how these press releases are written.
- dmd 3y agoThis is less energy put into the system than that given by a child splashing in the waves at the beach.
- yummypaint 3y agoIf many of the people replying to this comment had read the article, they would know that the low power device in question sends data by altering its reflectivity. It's metaphorically like covering and uncovering a retroreflector to send signals to a person a mile away with a powerful spotlight or laser pointed at you. It seems reasonable to be concerned about what this significantly stronger and likely highly-directed signal might do to biological things it encounters on its way.
- cogman10 3y agoI wish the article had a reference to the actual power used. It SOUNDS like it's quiet minimal. In which case, it'd be hard to imagine you are dealing with biologically devastating energy. That said, the unidirectional nature of this approach also means that actual life that could be affected is a lot smaller than what happens with sonar, where the signal is blasted in all directions at a very high power.
- isoprophlex 3y agoThis, or something very similar, was posted a long time ago here. I cant find it anymore, sadly, but it was a backscatter-based communication platform that used very low power in the underwater part... And illuminated that with 210 dB sound. I guess this is similar, and equally disruptive to sea life.
- EricMausler 3y agoThis is cool. I'm not sure if I missed it, but did they address how a signal is generated by the array in the first place? My current understanding is that the device will echo a signal back to the source, not propagate it forward or create a signal. Is it right to assume low power sensors exist and would be hooked up to this array, and then when the sensor triggers the array echos the signal to the other receiver?
- IshKebab 3y agoI'm pretty sure only one side of the communication system is "battery free". The other side is a standard phased array.
- chrisBob 3y agoIt might work at distances longer than 300m, but "they ran out of space on the dock." That seems like such a silly limitation to bring up twice in the writeup.
- hinkley 3y agoWow. If it’s “long distance” put the unwieldy piece where you have reserved space and move the less complex piece to borrowed space. Like another jetty, or a beach, or here’s a crazy idea: on a seaworthy vessel. You know, to test your marine communications device on a marine vehicle?
- mojomark 3y agoYeah, I've worked in this space for many years (more on the autonomous vehicle side, but certainly work with acoustic folks) and am very familiar with the WHOI affiliates and the ONR sponsors. You're not wrong. The multiple reference to the dock being too short to perform longer range testing also struck me as odd. It's very simple to get an academic or industry partner to strap a device on a two boats for a test. It's done all the time. WHOI is always testing vehicles. Something's not adding up.
- RobotToaster 3y agoSounds like a passive aggressive way of saying "tight ass funders didn't give us enough money to test this shit properly"
- deleted 3y ago[deleted]
- jgeada 3y agoIt's an MIT press release. Technique probably doesn't work at any interesting distance, but this way they can make it sound as if they've discovered something incredible without ever having to acknowledge that they know it won't work as described.
- mikewarot 3y agoThis sounds like an acoustic analog of the radio tracking device that was disclosed by Snowden a decade ago involving a quarter wave antenna that was selectively grounded. It was trackable at 20 miles, and totally passive. It could run for months on a single coin cell battery.
- beebeepka 3y agoI guess I was so enthralled with the rest, that I have missed this device. If it's totally passive, what's the battery for?
- myself248 3y agoObserving the parameter being monitored and deciding whether to ground or not ground the resonant element. "Passive" in this case meaning that none of the battery power was turned into RF. It did not produce any RF. It merely absorbed more or less RF to encode information.
- Cthulhu_ 3y ago"Passive" in this case meant it didn't emit its own signals per se; active sonar emits an audible noise (which can easily be traced back to an origin), passive sonar just listens.
- dylan604 3y agoThe trove of information released around the time of the Snowden leaks are not all necessarily from Snowden. There was a second leak that everyone likes to attribute to Snowden. Most of the info on the gadgets that I had seen seem to all be from the second source. But, yeah, they had some pretty cool toys.
- muxator 3y agoNow this is really really cool (technologically; let's not talk about the implications for people's freedom). Do you happen to have some pointer were read more about this? Thanks
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- ck2 3y agoCan they use this to stop killing whales when they try to talk to military subs halfway around the world? (the current method is like a person standing next to a jet plane taking off to underwater life)
- Mountain_Skies 3y agoWonder how well it would work for things like RC submarines. The distance increase isn't all that valuable for RC but the lower power required sounds very useful.
- andsbf 3y agoIt seems to be a directional technology, so I'm not sure it would be applicable to RC submarines
- backendanon 3y agoAs a former Submariner and Sonar Technician (trained in oceanography and underwater acoustics), it's interesting that such low power could be used. Long range underwater transmission of sound isn't a new thing. It's possible to passively track targets for up to 3000 nautical miles when the audio gets trapped in the deep sound channel. The device discussed in the article has only achieved a distance of 300 meters using a slightly modernized version of sonar transducers and receivers that have been around for a very long time. I've seen MIT ocean projects meet the real world and go poof, but it's good to see people are out there trying to figure things out again, in the world after the pandemic.
- mikepurvis 3y agoAcoustic modems are fascinating devices— you're transmitting at most tens of bits per second before error correction. To make such a paltry amount of data do anything useful is a pretty interesting challenge. You're limited to just bare telemetry and a few status flags / commands.
- acters 3y agoalso substantially slower than the speed of light, while not the biggest factor is also slower than other forms of transmission. As you said, there is a lot of noise that needs powerful error correction to be used, such as how the Reed-Solomon code was used in deep space communication. Prepackaging information before relying on wireless communication is usually the most necessary part of any reliably complex system.
- vorpalhex 3y agoThis stuff is for automated buoys or sensors, not for pushing video frames. Being to push a handful of ints every few seconds is more than enough for a lot of cases, especially if the "modem" (radio?) is cheap enough.
- dylan604 3y agobut why do buoys or sensors need to transmit that data underwater? They could easily do that via radio transmissions above the surface. to me, anytime underwater communication is concerned, it is solely to be in the realm of military submersed vessel communication. There's no compelling reason for any other communication to undergo the expense of underwater transmission.
- peter_d_sherman 3y agoRelated: Van Atta Reflector Array https://www.radartutorial.eu/17.bauteile/bt46.en.html https://www.radartutorial.eu/17.bauteile/bt46.en.html 1955 Patent - Lester Clare Van Atta - "Electromagnetic reflector": https://patents.google.com/patent/US2908002A https://patents.google.com/patent/US2908002A https://patentimages.storage.googleapis.com/83/5b/aa/c388e1709d7159/US2908002.pdf https://patentimages.storage.googleapis.com/83/5b/aa/c388e17...
- eternityforest 3y agoWill this cause trouble for the animals that live near it?