What is an EPIRB?
An Emergency Position Indicating Radio Beacon EPIRB is a safety device designed to transmit a satellite signal pinpointing a vessel or an individual in a distress situation. An EPIRB contains several different technologies and instruments which are vital for both alerting and detection. In a distress situation at sea, an EPIRB will activate automatically via water sensors, however, most can also be activated manually by using an activation switch.
Upon activation, a 406MHz signal will be transmitted to the Cospas-Sarsat satellite system. This signal is called the primary alerting signal, and it is coded within the distressed vessel/owner unique ID number and GPS position.
Simultaneously with the primary alerting signal, the 121.5MHz and the automatic identification system signals (AIS) are also activated and will begin transmitting. These additional two signals are used for homing to identify the specific location. The 121.5MHz VHF/AM frequency is used by airplanes and helicopters, whereas the AIS signal is a maritime VHF frequency that alerts any surrounding vessels within the reach of the signal. In addition, the visual LED and IR-LED technologies will begin flashing. The visual LED can be detected by the human eye and the IR-LED is detected by professional SAR personnel using IR-glasses.
The Cospas-Sarsat satellite system
The latest Jotron EPIRB acknowledges the signal via the Galileo satellite and the Return Link System (RLS). RLS is not yet recognized or in use globally, however, Australia, most of Europe and the USA to name a few locations are in full operation. An EPIRB including RLS activation offers visual confirmation directly on the unit when the distress signal has been received. It is important to be aware that an RLS confirmation does not confirm that anyone is physically enroute to assist, but rather that the primary alerting signal has been received.
An EPIRB operating within the Cospas-Sarsat satellite system is designed and produced with either automatic release or manual release, meaning it will be either a Category 1 or Category 2 EPIRB. In general, professional vessels must abide international or national regulations and will thereby have a Category 1, automatic release EPIRB installed on-board.
The difference between an automatic release (CAT1) or a manual release (CAT2) EPIRB relates to the type of bracket the EPIRB is mounted within. An automatic release bracket includes a mechanism called a hydrostatic release unit (HRU), which automatically releases the EPIRB from the bracket when submersed into water at depth 3-5 meters. The EPIRB will float to the surface of the water and begin transmitting the distress signal via the water activation sensors.
When using a manual bracket, the EPIRB must physically be removed from the bracket before it can be activated. Once removed the EPIRB is manually activated using the activation switch or via the water activation sensors.