ULF stands for Ultra Low Frequency. It designates the radio spectrum band between 300 Hz and 3 kHz. Because these extremely long waves can penetrate earth and seawater, they are primarily used for specialized military communications, such as reaching deeply submerged submarines, or for geophysical surveying.
Heard on the job
The base relies on ULF transmissions to send short text messages to subs without requiring them to surface.
Also heard as
- Ultra low frequency