GORDO’S SHORT CIRCUITS

DFing Emergency Beacons

Emergency Position Indicating Radio Beacons (EPIRBs) and Personal Locator land Beacons (PLBs) (Photo A) have gone to digital signaling of distress calls on 406 MHz. When activated, they now transmit a digital data-burst to geostationary and low-Earth-orbit satellites. This burst of data includes their specific 15-digit Unique Identification Number, as well as latitude and longitude from their built in GPS.

Ground controllers receiving the satellite-repeated real-time signal can now instantly see the latitude and longitude (lat/lon) where the signal has been activated, and notify appropriate authorities responsible for launching a local mountain or at-sea rescue.

But don’t put away your 121.5 MHz EPIRB and PLB direction-finding (DF) distress and emergency locator receive gear, as activated EPIRB or PLB transmitters will continue to send out that low power 50-milliwatt homing siren-type radio signal.

In steep terrain, or heavy seas, this low power signal can lead you directly to the crash or sinking scene, sometimes faster than just a lat/lon position given you by authorities