[HN Gopher] Device offers long-distance, low-power underwater co... ___________________________________________________________________ Device offers long-distance, low-power underwater communication Author : marban Score : 44 points Date : 2023-09-06 16:56 UTC (3 hours ago) (HTM) web link (news.mit.edu) (TXT) w3m dump (news.mit.edu) | mikewarot wrote: | This 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 wrote: | I 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 wrote: | Observing 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. | backendanon wrote: | As 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. | soperj wrote: | I'm guessing this will really be hell for whales. | [deleted] | Gys wrote: | [flagged] | RalfWausE wrote: | [flagged] | ck2 wrote: | Can 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) | chrisBob wrote: | It 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. | RobotToaster wrote: | Sounds like a passive aggressive way of saying "tight ass | funders didn't give us enough money to test this shit properly" | jgeada wrote: | It'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. | hinkley wrote: | Wow. | | 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? | dylan604 wrote: | My 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. | backendanon wrote: | At 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. | awei wrote: | This was also my first thought. | EricMausler wrote: | This 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 wrote: | I'm pretty sure only one side of the communication system is | "battery free". The other side is a standard phased array. | Mountain_Skies wrote: | Wonder 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. ___________________________________________________________________ (page generated 2023-09-06 20:00 UTC)