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What do you propose? Any sonar-equivalent involves broadcasting (in this context, broadcasting nearly continuously). Any broadcast makes it trivial to locate

What do you propose? Any sonar-equivalent involves broadcasting (in this context, broadcasting nearly continuously). Any broadcast makes it trivial to locate you. Submarines go to great lengths to be as quiet as possible so that the acoustics of the engine, ship, etc. can't be caught in a microphone. Any sort of EM radiation is child's play to trace compared to that. The content of the message and the frequency of the message don't matter - any sort of signal means you can be monitored and your location determined.

throwaway09223 4y ago
Well, an obvious proposal would be to send out a drone and transmit the sonar ping from a different location. You're right in that a broadcast is required, but I don't see why the broadcast should have to come from the sub itself.
- Arainach 4y ago
  The threat model isn't a torpedo, it's knowing where the enemy's subs are (and aren't). "There's a sub within half a mile of this point" is likely 90% as bad as "there's a sub exactly here" for most missions. While water motors are not exactly my area of expertise, I would also expect that drone/torpedo motors are significantly louder than submarine engines and that launching or recovering a drone is itself a fairly noisy event that exposes the sub to traditional acoustic tracking.
  - throwaway09223 4y ago
    Sure, all valid issues. It for sure would expose the general vicinity. In terms of noise, keep in mind that submarines have all sorts of concessions already. A diesel-electric sub is quieter than a nuclear sub, but it has to surface every two days or so to get air to run its very noisy diesel generators. I think a battery powered electric drone should be far quieter than any sub technology we have (steam/nuke is loud, diesel is louder). The quiet systems we have are all electric and therefore have limited energy capacity.
- maxwindiff 4y ago
  Wouldn't the sub itself also reflect the ping and give itself away?
gooseh 4y ago
Is detection of EM radiation really that easy? Broad parts of the EM spectrum are heavily attenuated by water - this is what makes underwater comms difficult.

throwaway09223 4y ago

Well, an obvious proposal would be to send out a drone and transmit the sonar ping from a different location. You're right in that a broadcast is required, but I don't see why the broadcast should have to come from the sub itself.

Arainach 4y ago
The threat model isn't a torpedo, it's knowing where the enemy's subs are (and aren't). "There's a sub within half a mile of this point" is likely 90% as bad as "there's a sub exactly here" for most missions. While water motors are not exactly my area of expertise, I would also expect that drone/torpedo motors are significantly louder than submarine engines and that launching or recovering a drone is itself a fairly noisy event that exposes the sub to traditional acoustic tracking.
- throwaway09223 4y ago
  Sure, all valid issues. It for sure would expose the general vicinity. In terms of noise, keep in mind that submarines have all sorts of concessions already. A diesel-electric sub is quieter than a nuclear sub, but it has to surface every two days or so to get air to run its very noisy diesel generators. I think a battery powered electric drone should be far quieter than any sub technology we have (steam/nuke is loud, diesel is louder). The quiet systems we have are all electric and therefore have limited energy capacity.
maxwindiff 4y ago
Wouldn't the sub itself also reflect the ping and give itself away?

gooseh 4y ago

Is detection of EM radiation really that easy? Broad parts of the EM spectrum are heavily attenuated by water - this is what makes underwater comms difficult.