alt Hacker NewsA note to just be a bit careful passively monitoring ocean acoustics, it’s easy to fall foul of military / security forces, they don’t like anything that can fingerprint a vessel.
I worked on DAS acoustic monitoring for subsea power cables (to monitor cable health!), turns out they are basically a submarine detection system.
Replies
Good advice but there's a bit of a difference between a device (or even several) you can knock together yourself and throw out of the side of a (surface) boat vs access to a whole undersea cable which (I have just learned) is what you need for DAS. Plus, if you can do it yourself with virtually no resources, it's a safe bet that any potential adversaries are already doing something many orders of magnitude greater.
Supposedly new submarines are so quiet that they can't be detected anyway. I'm sure there's a large element of exaggerating abilities here, but there's definitely an element of truth: in 2009, two submarines carrying nuclear weapons (not just nuclear powered) collided, presumably because they couldn't detect each other. If a nuclear submarine cannot detect another nuclear submarine right next to it then it's unlikely your $5 hydrophone will detect one at a distance.
Of course, none of this means that the military will be rational enough not to be annoyed with you.
[1] https://en.wikipedia.org/wiki/HMS_Vanguard_and_Le_Triomphant...
DAS has really been taking off in the marine bioacoustics world!
https://www.birds.cornell.edu/home/deep-listening/
https://depts.washington.edu/uwb/revolutionizing-marine-cons...
Very cool and very powerful technology, it'll be interesting to see how fiber sensing progresses, especially with how much undersea fiber already exists. For subsea power cables, is there a parallel fiber dedicated just for DAS monitoring? Do these get bundled in with data fiber runs as well? I've been curious how well DAS can work over actively lit / in-service fiber.
I used to be a submariner and now work in an unrelated acoustic space (acoustic analysis of the electric grid), but I'd love to learn more about the DAS world — my email is in my profile.
I know a man who built a fish shaped vehicle, and was immediately approached by the men in black...
Even biulding the equipment. There are rules about hydrophones at certain certain frequencies. Just putting the plans online might runafoul of export rules. Beware of stringing multiple hydrophones as this article suggests. Put too many on a system and you are into possible beamforming territory ... the tech used for geolocating noises underwater. The USN gets kinda twitchy about such things.
https://www.ecfr.gov/current/title-22/chapter-I/subchapter-M...
(Search for hydrophone)
as if they own the oceans
Reminds me of how the Navy heard the OceanGate submarine implode immediately when it lost contact en route to the Titanic, but waited several days before they admitted that because at the time noone even knew they had such a system of hydrophones in place. I wonder what else they have that we don't know about. The oceans are not just unexplored as a habitat, but also as an intelligence theater.