Jim Creek Naval Radio Station is used by the US Navy to transmit commands to distant submarines.
I/Q Raw Recording
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Audio Sample
Example of MSKMinimum-Shift Keying (When Shift/Bd = 0.5. It is impossible to get this ratio to be lower than 0.5, hence it is called the 'Minimum' shift.) modulation used by VLFVery Low Frequency (3-30 kHz) transmitters.