Medium Frequency (MF) (MF)

The radio-frequency band from 300 kHz to 3 MHz.

Marine MF communications include the 2 MHz band used for ship-to-ship and ship-to-shore voice and digital selective calling. Range is influenced by frequency, transmitter power, antenna, time of day, atmospheric noise and ground-wave or sky-wave propagation.

The international MF distress and safety DSC frequency is 2187.5 kHz, while associated radiotelephony uses designated channels including 2182 kHz under applicable procedures. Equipment, watchkeeping and licensing requirements depend on the sea area and vessel.