EPIRB, ELT and PLB - Information from (CAP)

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: EPIRB, ELT and PLB : The Emergency Position Indicating Radio Beacon (EPIRB), Emergency Locator Transmitter (ELT), and Personal Locator Beacon (PLB) are devices specifically designed to transmit emergency signals to alert the SAR system and that can be located by satellites and by direction finding (DF) equipment. Each device is battery operated and engineered for a particular environment. EPIRBs are maritime devices and as such are required to be waterproof, corrosion resistant and able to float upright on their own (for those designed to float). : EPIRBs, ELTs and PLBs transmit on 121.5 MHz, 243 MHz, 406 MHz or on a combination of these frequencies. Those that transmit on 406 MHz are specifically designed to operate with the Cospas-Sarsat satellite system. (The actual frequency is 406.025 MHz but the beacon is typically referred to as 406 MHz.) Their signal consists of a 0.44-second burst of data transmitted every 50 seconds to polar orbiting and geostationary orbiting satellites. This data burst contains a unique identifier number that links each individual EPIRB, ELT or PLB to a registration database that contains information on the vessel or aircraft, and emergency points of contact. In the U.S., all 406 MHz EPIRBs, ELTs and PLBs are required to be registered with the National Oceanic and Atmospheric Administration (NOAA). Two of the three classifications of ELTs use 121.5 MHz frequency for distress alerting. However, the space-based monitoring of 121.5 MHz is expected to be terminated on 1 February 2009. While non-space-based systems could still monitor this frequency and all ELTs will keep the 121.5 MHz homing capability, the Cospas-Sarsat system will not be able to detect or determine the position of 121.5 MHz distress alerts once processing of 121.5 MHz signals by satellite is halted. : EPIRBs are devices for transmitting maritime distress alerts. Five classes of EPIRBs are of significance to U.S. SAR authorities but only the initial four listed below are authorized for use by U.S. vessels: : Class A EPIRBs operate on 121.5 and 243 MHz and are automatically activated. : Class B EPIRBs operate on 121.5 and 243 MHz and are manually activated. : Note: The U.S. Coast Guard intends to terminate the sale and use of all 121.5 MHz EPIRBs in the U.S. prior to 2007 : Category I 406 MHz Satellite EPIRBs are automatically activated, float free devices operating in the 406 MHz band internationally allocated for satellite EPIRBs. These devices are coded with vessel information and when activated, this coded information will be transmitted via the satellite system to the appropriate RCCs. These devices provide accurate location information worldwide. Safety of Life at Sea (SOLAS) : Convention and other classes of vessels (U.S. fishing vessels) are required to carry Category I 406 MHz Satellite EPIRBs. These EPIRBs transmit for at least 48 hours and have the 121.5 MHz homing capability. : Category II 406 MHz EPIRBs are similar to the Category I devices except the Category II EPIRBs are manually activated. Vessels are encouraged to replace aging 121.5 MHz EPIRBs with the 406 MHz Satellite EPIRBs. These EPIRBs transmit for at least 48 hours. These EPIRBs transmit for at least 48 hours and have the 121.5 MHz homing capability. : Inmarsat-E EPIRBs operate on 1.6 GHz L band via Inmarsat satellites, through Inmarsat-E CESs and relayed to RCCs. While the SOLAS Convention allows use of the Inmarsat E-EPIRB in lieu of 406 MHz satellite EPIRBs, the U.S. does not allow this option for U.S. ships. Inmarsat-E EPIRBs are, however, used by a limited number of foreign flag vessels, and U.S. RCCs can expect to receive occasional distress alerts from them. : Note: Some 406 MHz EPIRBs may also transmit a position within the distress alert. This position may be a one-time input from the ship’s navigation system or may be periodically updated from a GPS processor internal. : -wayne