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Interference and Avalanche Transceivers
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Technical note

Many electronic devices can affect avalanche transceivers. And metal, even in food wrappers, can affect a transmitting beacon. This page contains advice based on informal testing and the manufactures' instructions. Read your user manual for specific advice.

Recommendations

When searching, your consumer electronics (e.g., phones, cameras, music players, headed gloves, etc) need to be further away from your transceiver than when transmitting. (These devices haven't been shown to interfere with a beacon's transmissions.) Here are some examples of official recommendations:

  • The Tracker DTS manual says at least 15 cm (6 inches), the Tracker2 says 30 cm (12 inches), and the Tracker3 says at least 40cm (16 inches) when searching and at least one inch when transmitting.

  • Most Ortovox manuals recommend at least 30 cm (12 inches) from other electronics. The Ortovox 3+ owner's manual increased that to 50 cm (20 inches).

  • Mammut says at least 50 cm (20 inches).

My informal testing leads me to feel that the recommendation of 30 cm (12 inches) is a reasonable minimum. To be even safer, turn the devices off (which is what most manufactures suggest), but since this might be overlooked during the inevitable panic of a real rescue, it best to turn them off even when transmitting. And it is preferable to turn off your electronics when transmitting so you don't forget to turn them off when searching. If you need to keep them turned on, always keep them at least a foot from your beacon.

By contrast, metal layers can partially block a beaconís transmission.  We confirmed that something as seemingly innocuous as a few Gu gel packs (which contain metal sandwiched in between plastic layers) can drastically shorten a beaconís transmission range. Don't keep any suspected metallic layers in a clothing pocket that might overlap your transceiver.

Additional Considerations

  • Remember that a cell phone that is not being used still transmits a signal to the cell service periodically even when not placing a call. Even in "airplane" mode the power conversion can cause interference. 

  • MP3 music players can wreak havoc during a search. (I've seen a tiny no-name MP3 player that was in the front pocket of a searcher confound his transceiver.) And don't forget that GoPro strapped to your chest. In our informal testing, 30 to 50cm (12 to 20 inches) seems necessary if you want to "be a hero."

  • In search mode, irregular readings and decreased range can also be caused by other sources of electrical interference, such as power lines, lightning, and electrical generating equipment. Ironically, chairlifts also generate background "noise" that can affect the searching transceiver.

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  • The Petzl Tikka XP2 headlamp cautions, "Warning, when your lamp is lit and in close proximity to an avalanche beacon in receive (find) mode, it can interfere with the operation of the beacon. In case of interference (indicated by static noise from the beacon [you won't hear static on a digital beacon]), move the beacon away from the lamp until the noise stops, or switch off the lamp."

  • Black Diamond Heated Glove WarningBlack Diamond's heated gloves warn, "Electronically heated gloves interfere with avalanche beacon reception. Turn gloves off while searching. If you are buried with gloves turned on, the search beacon will see interference when it is within a 1/2 meter radius of the gloves." Although heated gloves aren't commonly used by backcountry skiers, they are becoming quite popular with snowmobilers. Turning off your gloves is one more thing you'll need to remember should calamity strikes.

  • Magnets can be a culprit, too:

    • Some transceivers use a magnetic switch (even though the switch might appear to be mechanical). It is possible, although not easy, to switch between Off, Send, and Search with an external magnet. The transceiver will return to its previous mode when the magnet is removed. This is another reason to avoid jackets with magnetic closures.

    • Some transceivers use a magnetic compass while searching (e.g., Mammut Pulse and Ortovox S1). It is especially important that you keep magnetic items away from these transceivers while searching. Be especially wary of magnetic closures on jackets.

    • The Black Diamond Magnetron carabiners include a warning saying that the carabiners should be kept 50cm (20 inches) from avalanche transceivers.

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