Avalanche transceiver
An avalanche transceiver or avalanche beacon is a type of emergency locator beacon, a radio transceiver (a transmitter and receiver in one unit) operating at 457 kHz for the purpose of finding people buried under snow. They are widely carried by skiers, particularly back country skiers for use in case a skier is buried by an avalanche. Before setting out on an expedition, all the members of a group activate their transceivers in the transmit mode, causing the device to emit low-power pulsed radio signals during the trip. Following an avalanche, if some members of the ski party are buried, the others may switch their transceivers from transmit into receive mode, allowing use as a radio direction finding device to search for signals coming from the lost skiers. The avalanche beacon is an active device powered by batteries; a ski suit may also contain a passive RECCO transponder sewn into the clothing. Early avalanche transceivers transmitted at 2.275 kHz. In 1986, the international frequency standard of 457 kHz was adopted, and this remains the standard today. Many companies manufacture transceivers that comply with this standard. An avalanche transceiver is not considered a preventive measure against possible avalanche burial, but rather