A Standard Frequency for Avalanche Beacons

ISSW 1986

Currently, two different frequencies are in use in Europe for avalanche beacons. After an in-depth presentation of the selection criteria and the performance of both frequencies against them, a brief analysis of the current state of standardization efforts in Europe documents the stron tendency to converge to 457 kc.

European Law and Standards Affecting Avalanche Beacons

ICAR Convention 2000

In the past two years, new directives issued by the European Government have led to a change in the legal status of avalanche beacons and to an overhaul of the European standard EN 300 718 for avalanche beacons. The standard will be harmonized throughout Europe and also provide some technical improvements.

Determining the Width of a Search Strip for Avalanche Beacons

ISSW 2000

The width of the coarse search strip that is applied when scanning an avalanche is a major factor influencing the time to locate buried victims. Wider search strips help in reducing this time. If the width is chosen too large, there is some risk of not detecting a buried person.

Various methods have been proposed and used for the determination of the optimum width of the coarse search strip. The results obtained by these methods are widely varying because of their dependency on the ability of the testing persons. Also, some methods make assumptions about density functions. These assumptions are not very solid. All of these methods require a substantial number of experiments to obtain useful data.

A new method is proposed which, while reducing the testing effort considerably, removes as much dependency from the testing person's ability as possible. The method can also be applied to multiple antenna beacons. The results provided are at least as accurate and reliable as the results obtained by earlier methods.

Compatibility of Avalanche Transceivers

The Avalanche Review 2004

In their recent story published in the Avalanche Review Edgerly and Hereford propose some actions to be taken to improve on the compatibility among avalanche transceivers. Most of their general conclusions are appropriate, but some important details require a clarification. In particular, new standard requirements should not lead to inferior performance.

On the Effects of Receiver Bandwidth on the Performance of Avalache Beacons

ISSW 2006

Contrary to transmitter frequency tolerance, the receiver bandwidth is not standardized for avalanche beacons. Some transmitters even transmit outside the specified tolerance range. This may give raise to compatibility problems.

If the receiver bandwidth is widened to accommodate even out-of-band transmitters, receiver performance will be degraded. If the receiver bandwidth is made too narrow, this causes unpleasant audible effects and renders proper digital signal evaluation impossible. Simulation results for various settings are presented in audible and display format. They indicate that the optimum bandwidth for achieving long range is less than what would be required for good performance against transmitters that operate at the limits of the frequency tolerance. This can be mitigated by making the receiver adaptive to the transmitter's frequency.

Receiver bandwidth should be optimized for best performance in terms of range. Out-of-spec transmitters should be replaced.

Avalanche Transceivers & Multiple Burials

TAR 2008

Avalanche beacons and multiple burials are a controversial issue. By evaluating properly selected signal features and by using suitable classification algorithms, it is possible to resolve multiple burial situations correctly in most of the cases, thus providing good guidance especially to users that never or rarely practice multiple burial searches. Some modifications to the standard EN 300 718, however, would make the process even more reliable.

Electromagnetic Compatibility of Avalanche Transceivers

Submitted for presentation at ISSW 2013, withdrawn after publication of similar paper by Genswein in TAR Vol. 31, No. 4, April 2013.

Every once in a while, the issue of ElectroMagnetic Compatibility (EMC) of avalanche transceivers is popping up. There are at least three mechanisms by which avalanche transceivers may suffer some kind of interference from other equipment. Besides the best known interference to a searching receiver, there may also be interference to a transmitting transceiver or even to a transceiver in any state. After explaining the mechanisms of interference, some hints are given on how to check for various types of interference.

"Field Line" Search Revisited

Poster presentation at ISSW 2014

The avalanche transceiver field line search is actually not a search along the field lines, but along the path given by the projection of the field lines onto the plane of the searching transceiver. The shape of the magnetic field that is emanating from a buried transceiver is investigated. The projection of the field lines onto the plane of the searching transceiver is calculated in a three-layered space: air, snow and soil. It depends on the orientation of the buried transmitter's antenna and on the dielectric properties of the individual layers. Some rules for optimized searching can be derived from the results of these calculations.

"Field Line" Search Revisited

ICAR Conference 2014 South Lake Tahoe, US

The avalanche transceiver field line search is actually not a search along the field lines, but along the path given by the projection of the field lines onto the plane of the searching transceiver. Some rules for optimized searching can be derived from the results of these investigations.

Barryvox History

August 10, 2017

The history of the Barryvox started almost 50 years ago. And the product is still very popular, which is not very common for an electronic device. The document describes the beginnings and the many facets of the Barryvox up to the most recent versions.

The document also covers the very first transceiver that was invented by John Lawton and the frequency and standardization issues.

Search Path

ICAR Conference Montreux 2022

Distance and direction information on the display of an avalanche transceiver operating in search mode depend on the incident field lines of the magnetic field that is produced by a buried transceiver. The two of then determine the path that a user will walk when doing a search. The search path is usually not a straight line towards the location of the buried transceiver, but may take an unexpected detour. The SearchPath program can be used to simulate search paths depending on many parameters such as different snow and soil layers, burial depth, buried transceiver orientation, searching transceiver elevation above the snow surface, number of antennas in the searching transceiver. The tool is useful for personal investigations/studies, designing challenging training scenarios, preparing graphics for documentation and manuals and for developing new (better?) transceivers.