Transceiver Interference
by Andy Dappen

An interesting article from Avalanche Canada is posted below about interfering electronics and objects that might render your avalanche transceiver useless. Distances between your unit and interfering devices/substances are important to note — in transmit/send mode all interfering objects should be 20 cm away (round-off to a foot) and in search mode all interfering objects should me 50 cm away from your unit (round-off to 2 feet). Two obvious things come mind for me that all of us who use transceivers for avalanche insurance should be doing:

1) Establish your own protocols. If you harness your transceiver to your chest, where can your phone, camera, music player, chocolate with foil wrapper be carried safely (e.g., opposite-side pant pocket or pack lid) and what’s in the danger zone (e.g., same-side pant pocket, coat pocket)? Same goes for carrying the transceiver in your pants pocket — where can other interfering objects be carried safely (e.g., opposite-side pants pocket, opposite side coat pocket, pack lid) and what’s in the danger zone (same-side coat pocket)?

2) Test your own transceiver. Put the electronics and interfering objects mentioned in the Avalanche Canada article next to your transceiver and see if other transceivers can detect your unit in transmit mode or whether the reception is being affected. This would be a good exercise to do with your ski/snowshoeing friends… to educate everyone and to see whose transceivers are most susceptible.

Transceiver Interference

From Avalanche Canada:…r-interference

An incident was recently reported to us where a person’s transceiver was made useless because of the small magnets in her jacket’s closure system. Several types of transceivers have a magnetic on/off or off/send/search switch. If you have a magnet close to these transceivers, they can randomly turn the unit off, or to search, or to send. Some transceivers also contain an electronic compass that can be highly sensitive to magnets and electromagnetic fields, especially during a search.

Magnets are just one of many items that can interfere with an avalanche transceiver’s signal. We need to be careful of all metallic objects and electronic devices. Research tells us to keep these items 20 cm away from transceivers in transmit mode, and 50 cm away when in search mode.

A partial list includes:
• Metallic foil (such as wrapping on food, candy or cigarettes)
• Cell phones
• Cameras
• MP3 music players
• Heated gloves
• Headlamps

A quick search for “transceiver interference” will give you some good articles. Also check out the online collection of papers presented at International Snow Science Workshops (ISSW). Montana State University provides a free searchable database of this research. You can find that collection here.

Backcountry users are an increasingly powerful voice and we have influence. Perhaps it’s time to let equipment manufacturers know that magnets in their products could mean the difference between life and death.

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