What is an Avalanche Transceiver?

An Avalanche Transceiver, or DVA (Détecteur de Victime d'Avalanches), is a transmitting and receiving device for low frequency electromagnetic waves (2.275 kHz). It helps locate avalanche victims, or in the victim's case, helps be found under a few metres of snow.

First DVA: Skadi System

History

In 1940, the engineer F. Bächler thought to kit military troupes in danger of avalanches with electromagnetic transmitters. However, it wasn't until 1960 that his idea was developed, and later still, in 1968 that the American J. Lawton created the first transmitter/receiver that used a frequency of 2275Hz (this frequency is still used today).

In the 1970's, the companies Autophon AG (Swiss) and Pieps (Austrian) developed their first DVAs, working respectively 457Hz and 2275Hz. The two devices were incompatible, so the ICAR (International Commission for Alpine Rescue) established a single European frequency in 1984 (457kHz). Today, all DVAs work at a frequency of 457kHz.

How it works

The principle of a DVA is pretty basic. The antennae consists of an iron rod surrounded by an electromagnetic coil. Whilst emitting, an electric current travels through the coil, creating an electromagnetic field that is enhanced by the rod. When receiving, you use the DVA to follow the field lines. These field lines are detected by 3 antennaes included in the beacon. When a field maximum is found, you are the closest possible to the victim.

The beacon works on simple home batteries. and can be switched from receiving to emmiting mode. In a normal situation, a DVA should be on emmiting mode, and to save its power, emits brief signals at regular intervals. The power of the signal depends on the power of the batteries, so it is essential that you always have charged batteries.

The low frequency is chosen purposely for its properties: it is hardly influenced by snow, and loses little power when traveling through a human body for instance.

Where to buy

The best place to buy a DVA is probably internet. We would advise a recent model of Barryvox, but as long as you know how to use it (hence the application), any good quality DVA will do. Here are a few websites that sell them. WATCH OUT! These websites haven't been checked thoroughly checked. We are not responsable for any problems (however unlikely) that may occur. The first website gives information about each DVA.

https://www.outdoorgearlab.com/

https://www.mammut.ch/

https://www.auvieuxcampeur.fr/