Submerged radio messages

jgf · 05-17-17, 06:46 PM

The reception depends on the frequency. VLF (very low frequency, about 100kHz-200kHz) transmissions can travel quite far underwater, though only to a depth of 20-30ft; the USN experimented with this in the thirties, the antennas were hundreds of feet long, suspended on low towers along the coast. Downside is this frequency band is extremely susceptible to noise, especially since they were using amplitude modulation back then. The system is still in limited use today, on a much lower band (https://en.wikipedia.org/wiki/Lualualei_VLF_transmitter).

Video of dedication of USN VLF station in 1953 - http://www.clipxaab.com/NFdvVXZNUy04VDRY

Also, though I've no idea if Uboats used this, some submarines had antennas on buoys that could be released when submerged and reeled back in, allowing both transmission and reception while submerged. A modern variation of this, using satellite relays, is used by nuclear subs today.

https://en.wikipedia.org/wiki/Commun...ith_submarines

Thread Tools
Show Printable Version Email this Page
Display Modes
Switch to Linear Mode Switch to Hybrid Mode Threaded Mode

05-17-17, 06:46 PM	#6
jgf Watch Join Date: Jan 2012 Posts: 21 Downloads: 26 Uploads: 0	The reception depends on the frequency. VLF (very low frequency, about 100kHz-200kHz) transmissions can travel quite far underwater, though only to a depth of 20-30ft; the USN experimented with this in the thirties, the antennas were hundreds of feet long, suspended on low towers along the coast. Downside is this frequency band is extremely susceptible to noise, especially since they were using amplitude modulation back then. The system is still in limited use today, on a much lower band (https://en.wikipedia.org/wiki/Lualualei_VLF_transmitter). Video of dedication of USN VLF station in 1953 - http://www.clipxaab.com/NFdvVXZNUy04VDRY Also, though I've no idea if Uboats used this, some submarines had antennas on buoys that could be released when submerged and reeled back in, allowing both transmission and reception while submerged. A modern variation of this, using satellite relays, is used by nuclear subs today. https://en.wikipedia.org/wiki/Commun...ith_submarines