EPIRB

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Category I can be either activated manually or set to activate automatically in the event of a disaster at sea. These EPIRBs are generally housed in a specially designed bracket on deck and the buoyant beacon is designed to rise to the surface and emit two signals, an emergency homing signal on 121.5 MHz and a digital identification code on 406 MHz that can be used to identify the stricken vessel.

Category II EPIRBs are similar to Category I EPIRBs but are generally manual activation only.

Class B EPIRBs, also called Category B or “Mini B”, operate a 121.5 MHz homing signal only and are usually manual activation only units. Due to their limitations, Category B EPIRBs are slowly being phased out.

When a beacon is activated, one or more satellites pick up its transmission. The satellite transmits the signal to a ground control station that processes the signal and forwards the data, including approximate location, to a national authority that in turn forwards the data to a rescuing authority, such as the Coast Guard. EPIRBs with optional GPS receivers will send exact position data rather than depending upon the satellite doppler shift method of determining position.


* EPIRB is an acronym for Emergency Position Indicating Rescue Beacon