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How would the proximity sensors work? The can’t go active sonar…

by idoh 5y ago

dotancohen 5y ago
Optical, perhaps? How much light is at these depths? How do the subs avoid terrain?
- jvzr 5y ago
  I remember (barely) from a diver friend that colors disappear below 20 meters (everything appears blue, unless a bright light is shone), and sun light disappears completely below 70 meters. You'd assume that an optical system with flood lights could theoretically work, but then it would be pretty simple to monitor for light at these depths (for counter-intelligence/retaliatory purposes)
- nradov 5y ago
  Subs avoid terrain using charts and dead reckoning, including inertial navigation systems. They typically come to periscope depth occasionally to get a navigational fix. In 2005 a US submarine allided with an underwater mountain due to a navigational error. https://www.cbsnews.com/news/whos-to-blame-for-sub-accident/ https://www.cbsnews.com/news/whos-to-blame-for-sub-accident/ There is little or no light at typical operating depths. Lidar can work to a limited extent in some water conditions but it's not something to rely upon for collision avoidance.
  - sbierwagen 5y ago
    >Lidar can work to a limited extent in some water conditions but it's not something to rely upon And, of course, it's an active sensor. An adversary could detect the emitted light.
zoomablemind 5y ago
Low power high freq radio waves? These should rapidly attenuate underwater, so not much of giveaway, but could be enough for proximity scans around the sub. Is there some spectrum of emissions from an even stealthy sub, some kind of "local presence"? The immediate massive obstacles would result in distortions to such a self-presence profile. So the sensors could be trained to detect such local distortions, almost like some fish have a lateral line of nerves supposedly helping detect current flows etc. [1]. [1]:https://en.m.wikipedia.org/wiki/Lateral_line https://en.m.wikipedia.org/wiki/Lateral_line
- zoomablemind 5y ago
  >...So the sensors could be trained to detect such local distortions, almost like some fish have a lateral line ... Turns out, this has been modeled already (2007): [1]:https://www.photonics.com/Articles/Fish_Navigation_System_Recreated_for_Submarines/a28572 https://www.photonics.com/Articles/Fish_Navigation_System_Re...
kragen 5y ago
Ultrasound, magnetic, eddy-current metal detection, conductivity detection by conducting current through water, red light, VNIR, antineutrino detectors...

How would the proximity sensors work? The can’t go active sonar…

by idoh 5y ago

How would the proximity sensors work? The can’t go active sonar…

dotancohen 5y ago

Optical, perhaps? How much light is at these depths? How do the subs avoid terrain?

jvzr 5y ago
I remember (barely) from a diver friend that colors disappear below 20 meters (everything appears blue, unless a bright light is shone), and sun light disappears completely below 70 meters. You'd assume that an optical system with flood lights could theoretically work, but then it would be pretty simple to monitor for light at these depths (for counter-intelligence/retaliatory purposes)
nradov 5y ago
Subs avoid terrain using charts and dead reckoning, including inertial navigation systems. They typically come to periscope depth occasionally to get a navigational fix. In 2005 a US submarine allided with an underwater mountain due to a navigational error. https://www.cbsnews.com/news/whos-to-blame-for-sub-accident/ https://www.cbsnews.com/news/whos-to-blame-for-sub-accident/ There is little or no light at typical operating depths. Lidar can work to a limited extent in some water conditions but it's not something to rely upon for collision avoidance.
- sbierwagen 5y ago
  >Lidar can work to a limited extent in some water conditions but it's not something to rely upon And, of course, it's an active sensor. An adversary could detect the emitted light.

zoomablemind 5y ago

Low power high freq radio waves? These should rapidly attenuate underwater, so not much of giveaway, but could be enough for proximity scans around the sub. Is there some spectrum of emissions from an even stealthy sub, some kind of "local presence"? The immediate massive obstacles would result in distortions to such a self-presence profile. So the sensors could be trained to detect such local distortions, almost like some fish have a lateral line of nerves supposedly helping detect current flows etc. [1]. [1]:https://en.m.wikipedia.org/wiki/Lateral_line https://en.m.wikipedia.org/wiki/Lateral_line

zoomablemind 5y ago
>...So the sensors could be trained to detect such local distortions, almost like some fish have a lateral line ... Turns out, this has been modeled already (2007): [1]:https://www.photonics.com/Articles/Fish_Navigation_System_Recreated_for_Submarines/a28572 https://www.photonics.com/Articles/Fish_Navigation_System_Re...

kragen 5y ago

Ultrasound, magnetic, eddy-current metal detection, conductivity detection by conducting current through water, red light, VNIR, antineutrino detectors...