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Radio waves don't work well through salt water. Even VLF signals have trouble going past like 30 meters. There's some super duper low frequency radios but it's
by Rebelgecko 3y ago
Radio waves don't work well through salt water. Even VLF signals have trouble going past like 30 meters. There's some super duper low frequency radios but it's still a one-way proposition - build a huge facility on land to communicate with subs, and if the sub needs to reply it has to surface. And even that limited setup is only doable by the military industrial complex of a small handful of nations.
- phire 3y agoBit of an understatement. ELF (Extremely low frequency) requires finding a section of earth's crust with very low conductivity that can be repurposed as an antenna. These antennas are very large, the US had one that was 45km long, the Soviet antenna is 60km long. The resulting signal has a wavelength of 3500-4500 KM, about a quarter of the earth's diameter. Because of this huge wavelength, the bandwidth is extremely low. The US system took 15 minutes to transmit a single 3 letter message. The system was only really useful for transmitting pre-agreed signals (which were usually along the lines of "surface and contact us for the actual orders"). But they also acted as a dead-mans switch, they continually transmitted an idle signal. If they stopped transmitting (which would still take several minutes to notice) subs would establish communication to check if a nuclear war had started.
- mckirk 3y agoThat's fascinating. I'm pretty sure you could post that as its own submission (if you find a suitable link) and it might do quite well.
- jareklupinski 3y agoI'd love to hear if the length requirement can be removed with advancements like phased-array systems or plasma antennas. Would be cool to be able to text across the world.