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.
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.