Mae'r cynnwys hwn ar gael yn Saesneg yn unig.
28 Medi 2021

Vigil finale: How do submarines communicate?

With over seven million people tuning into the gripping finale of BBC One’s submarine-based drama Vigil on Sunday, audiences might be wondering what life is like deep beneath the waves.

Most UK households are increasingly reliant on good phone and broadband connections to communicate, so it’s hard to imagine being on a vessel with little means of contacting the outside world.

The communications we use on land obviously don’t work in the same way for submarines underwater, but radio technology does help crews to communicate with other vessels and land bases.

How it works

Submarines use very low frequency radio waves for communication when submerged. Radio waves are absorbed quickly by seawater, and the deeper a submarine travels, the more water those radio waves need to get through. Very low frequency radio waves can only travel a few tens of metres. Submarines can deploy buoys equipped with antenna closer to the surface to enable them for communication when they are deeply submerged.

These very low frequencies only support narrow bandwidths, so only allow for low levels of data to be carried. This means normal voice communication isn’t possible, and only very slow data can be supported – submarines may use Morse Code, for example.

Submarines are sometimes equipped with on-board devices that can connect to the internet with higher data rates, including via satellite, but these can only be used when submarines rise to the surface. As seen on the show though, Navy submarines might not want to do this, as it could leave them vulnerable to detection. Ofcom’s Spectrum team works with the Ministry of Defence to help keep the UK Navy’s communications running smoothly. Our spectrum engineers help to troubleshoot problems vessels might experience with radio frequencies, such as interference.

This is another example of how important spectrum is for connecting critical services, every day.

There is more information about how Ofcom manages spectrum in the UK on our website.

Beth yw sbectrwm?

Allwch chi ddim weld na theimlo sbectrwm radio. Ond mae angen sbectrwm ar bob dyfais sy’n cyfathrebu’n ddiwifr – boed hynny’n setiau teledu, yn allweddi car digyswllt, monitorau babis, meicroffonau diwifr a lloerennau. Mae ffonau symudol yn defnyddio sbectrwm i gysylltu â mast lleol er mwyn i bobl allu gwneud galwadau ffôn a defnyddio'r rhyngrwyd.

Pam mae Ofcom yn rheoli sbectrwm?

Dim ond hyn a hyn o sbectrwm sydd ar gael, felly mae angen ei reoli’n ofalus. Mae bandiau penodol o sbectrwm yn cael eu defnyddio at ddibenion gwahanol hefyd. Er enghraifft, mae cwmnïau symudol yn defnyddio rhannau gwahanol o'r sbectrwm i gwmnïau teledu. Felly, mae angen ei reoli i sicrhau nad oes ymyrraeth ar wasanaethau ac nad oes amharu ar bobl ac ar fusnesau.

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