how do military submarines communicate with land and how long does it take.

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how do military submarines communicate with land and how long does it take.

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The US Navy maintains facilities that broadcast very slow speed encrypted data to submarines. In order to do so effectively, and for the signals to penetrate the water they have to use VLF frequencies between 3 and 30 KHz.they have to use such low frequencies because they need to penetrate salt water. Slow speed encrypted data communications are sent via very high powered transmitters which have to use enormous antenna systems due to the very long wavelengths.

There are a few ways. A submarine can deploy antennas above the water at periscope depth and communicate using ordinary radio frequencies like VHF or UHF. At shallow depths, say 20-40 meters, they use VLF frequencies. At depths beyond that, they have vety long cable antennas that they drag behind them that use ELF frequencies or float the VLF antenna to near the surface using a buoy. VLF and ELF communications are very slow and can only use text, no voice or video. They are also only way, from land to sea. because they need large amounts of power and massive antennas that submarines can’t carry.

Another possibility is for submarines to tap into existing undersea cables or to emit acoustic waves that can be picked up by undersea microphones, however the latter would give away a submarine’s location.

There is a facility fairly close to where I live. I’ve never seen it but have been told it is made in an entire valley between two mountains.

well, they have little fish inside the boat, and they tell the fish what to say, and then the fish will swim to land and give them the message

Generally they communicate using radio. This means that when a submarine is deep under water, they generally can’t communicate with land. Submarines either have to come to the surface, or come near the surface and release an antenna buoy in order to send and receive signals. In the old days these signals were basically shortwave radios with a range of a few hundred miles at most. Now, its usually encrypted satellite communications that work globally.

While a submarine is in communication, it only takes a fraction of a second to send data back and forth. However depending on the mission, a submarine might go for days or weeks between coming up for communications. When the sub is out of communication, the messages get stored and are sent when the sub next checks in, sort of like how text messages just pile up when your phone is turned off and all get delivered at once when you turn it back on.

There are some other special ways that subs sometimes communicate. There are underwater sonic telephones which allow communication over relatively short distances (a few miles) underwater from one submarine to another, or from a sub to a surface ship. There are also special types of ultra-low frequency radio-waves which can be picked up under water, as long as you aren’t too deep. These are used to sent special messages like a warning that a nuclear war is about to start. Only some submarines are equipped with this kind of signaling system, and it only works under certain circumstances.