Emergency Position Indicating Radio Beacon (EPIRB):
- EPIRB stands for Emergency Position Indicating Radio Beacon.
- An EPIRB is meant to help rescuers locate you in an emergency situation, and these radios have saved many lives since their creation in the 1970s.
- Boaters are the main users of EPIRBs.
- A modern EPIRB is a sophisticated device that contains:
- A 5-watt radio transmitter operating at 406 MHz (see How the Radio Spectrum Works for details on frequencies).
- A 0.25-watt radio transmitter operating at 121.5 MHz.
- A GPS receiver once activated, both of the radios start transmitting. Approximately 24,000 miles (39,000 km) up in space, a GOES weather satellite in a geosynchronous orbit can detect the 406-MHz signal. Embedded in the signal is a unique serial number, and, if the unit is equipped with a GPS receiver, the exact location of the radio is conveyed in the signal as well. If the EPIRB is properly registered, the serial number lets the Coast Guard know who owns the EPIRB. Rescuers in planes or boats can home in on the EPIRB using either the 406-MHz or 121.5-MHz signal.