New Amateur VLF Transatlantic Record

[VE3WI Dave]

From the ARRL Website:

Very low frequency (VLF) enthusiast Joe Craig, VO1NA, reports that Stefan Schaefer, DK7FC, copied his 50-character message transmitted from Newfoundland on 8.271 kHz, with a radiated power of 10 mW.  “This is a new record for amateur transatlantic VLF,” Craig told ARRL. “The mode used was EbNaut by Paul Nicholson. EbNaut is a synchronous coherent BPSK mode for use at VLF and low LF. Craig’s tower supports a VLF RL (rotated L) 10-meter (33 feet) average height and 100 meters (328 feet) long. VLF is the ITU designation for radio spectrum in the range of 3 – 30 kHz, corresponding to wavelengths from 100 to 10 kilometers, respectively.  “Since VLF waves can penetrate at least 40 meters (131 feet) into saltwater, they are used for military communication with submarines,” Craig noted.


The US Navy uses 24 kHz VLF to contact their subs.  They have several sites with massive antennas that transmit using 1 MW or more.  Here's a link to one of them:

https://en.wikipedia.org/wiki/Jim_Creek_...io_Station

73
Dave, VE3WI

[VA3KOT John]

Before I left the UK in 1981 I lived in a small town called Rugby (where the game with the same name originated). Rugby was home to the Rugby Radio Station, a VLF transmitter that was used to send messages to Royal Navy submarines anywhere in the world. The station had twelve towers, each 820ft tall to support the antenna wires and transmitted on a frequency of 16KHz using callsign GBR. A full description is at: 
https://en.m.wikipedia.org/wiki/Rugby_Radio_Station

[VE3WI Dave]

Thanks John.  I just read about Rugby & its replacement at Skelton.

Interesting that the Navy needs megawatts but hams get it done with milliwatts - except for the subsea bit :-)

Going from the ridiculous towards the sublime, several nations have used SLF (30 - 300 Hz) or ELF (3 - 30 Hz), which will penetrate several hundred meters into seawater.  The US once had a system operating at 76 Hz but it was decommissioned (google Project Sanguine).  According to Wikipedia, China has an ELF facility "the size of new York City" to talk to its subs.  India and Russia also use it.

73
Dave, VE3WI