How EPIRB's work

EPIRBs Emergency Positioning Indicating Radio Beacons or EPIRBs are compact, buoyant and portable emergency devices specifically designed to transmit a radio distress signal to alert emergency authorities of a need for rescue. Once activated, an EPIRB will continuously transmit a specific radio signal to be detected by satellites. Following satellite detection, the emergency position and specific location data is then relayed to related authorities to begin rescue operations.Several EPIRB models can be owner registered with a relevant rescue co-ordination authority. Following activation, an owner registered EPIRB will provide rescue operators with the owner's name and emergency contact details plus the type of vehicle/vessel needing rescue. EPIRB registration greatly improves rescue response times. HOW EPIRB's WORK One of the most important pieces of safety equipment available to any outdoor enthusiast, an EPIRB is the last line of defence for when all other means of self rescue have failed. KTi manufacture a complete range of EPIRB devices to suit all outdoor applications. If an EPIRB is activated, COSPAS/SARSAT picks up the signal, locates the source and passes the information to a land station. From there, the information is relayed to Rescue Coordination Centers, rescue vessels and nearby ships. This constitutes a oneway only communications system, from the EPIRB via the satellite to the rescuers. It employs low altitude, near polar orbiting satellites and by exploiting the Doppler principle, locates the 406 MHz EPIRB within about two miles. Due to the low polar orbit, there may by a delay in receiving the distress message unless the footprint of the satellite is simultaneously in view with a monitoring station. However, unlike SafetyNET, worldwide coverage is provided. As a satellite approaches a transmitting EPIRB, the frequency of the signals it receives is higher than that being transmitted; when the satellite has passed the EPIRB, the received frequency is lower. This creates a notable Doppler shift. Calculations which take into account the Earth's rotation and other factors then determine the location of the EPIRB. Each 406 MHz EPIRB incorporates a unique identification code. Once the satellite receives the beacon's signals, the Doppler shift is measured and the beacon's digital data is recovered from the signal. The information is time-lagged, formatted as digital data and transferred to the repeater downlink for real time transmission to a local user terminal. The digital data coded into each 406 MHz EPIRB's memory indicates the identity of the vessel to SAR authorities. They can then refer to the EPIRB registration database for information about the type of vessel, survival gear carried aboard, whom to contact in an emergency, etc. The data includes a maritime identification digit (MID, a three digit number identifying the administrative country) and either a ship station identifier (SSI, a 6 digit number assigned to specific ships), a ship radio call sign or a serial number to identify the ship in distress. With the Inmarsat-E satellite EPIRB's, coverage does not extend to very high latitudes, but within the coverage area the satellite connection is instantaneous. However, to establish the EPIRB's geographic position, an interface with a GPS receiver or other sensor is needed. < Prev