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Electromagnetic Interference and Avalanche Beacons

photo by Bob Peters  

Photo by Bob Peters


Tips to give you the best chance of being located if you're ever caught in an avalanche. 

by Tyler Wenzel


I recently read someone mention the potential danger of running a GoPro camera when in areas that you would be using an avalanche beacon for protection—the assertion was quite surprising to me. I could understand a GPS or even an older cell phone causing interference for the avalanche beacon, but a simple camera?


I found two sources of information helpful in researching this (links to both can be found below). The primary source was compiled based off manufacturer recommendations from Beacon Review. The other provided anecdotal evidence from a few unscientific, but seemingly significant tests.


First off what is electromagnetic interference? Put simply, any electronic device will emit radio and electronic signals. These signals can in turn effect the operation of other electronic devices—electromagnetic interference. Any electric device will cause interference, some much more than others. Something like a GPS or a Microwave (although skiing with a microwave probably comes with more issues than just interfering with an avy beacon) will release a lot of signals where as a camera or iPod (one without networking) not as much.


As a result any electronic device has the potential to prevent your avalanche beacon from functioning properly. The very minimum beacon manufacturers recommend is a 15 cm (~6 inches) distance from any electronic device. Most manufacturers seem to recommend 30 cm (~12 inches) and some as many as 50 cm (~20 inches).


However it is electromagnetic interference, so magnets can also play a large role. It’s easy to forget about, but some ski jackets use magnets to keep pockets and flaps closed. Particularly if your beacon would be right next to one of these magnets, it would completely skew your results. In fact some beacons can have their modes inadvertently switched by the magnets in a jacket (for more information about this and specific models affected please see the link to BeaconReviews.com).  


The problem with interference is that it is seemingly random and varies wildly. For instance two iPhones of the same model may release a different amount of signal depending on many factors like slightly different build components to software settings like how often it is checking for notifications. You may test your beacon and it works fine right next to an electronic device, but another time it may not work. It’s just unpredictable.


One basic test someone ran using a GoPro camera (newest model) and a roughly two year old avalanche beacon. The receiver wouldn’t pick up the signal until it was 15 meters away, and even then the number would fluctuate between saying it was anywhere from 15 to 22 meters away or even lose the signal of the other beacon.


Now if GoPro camera’s having this effect surprised me, this next device really surprised me; a headlamp. Yes that is right, a light can prevent your beacon from working effectively. In face one manufacturer (Petzl) specifically mentions in their owner’s manual that: "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), move the beacon away from the lamp until the noise stops, or switch off the lamp."


Another test came from an individual with a beacon that provided analog response. The closer you got to the receiver, the more noise it would emit. He tested it by going around his house and getting near to electronic devices. Some things that you wouldn’t expect gave the most interference. For example between a laptop (with radio beacons for wireless networking) and the AC-DC power brick for the laptop guess which provided more interference? The power brick. It is the unpredictability of interference.


With these points in mind, take the following precautions when you are skiing with an avy beacon:


Leave any unnecessary electronics somewhere else. In a locker, your car, the lodge, at home, somewhere—just not on you!

  • Unplug the iPod. I like to listen to music when I ski sometimes—I admit it. It may not be the safest thing to do, but that is a debate for another day. But the iPod is one giant interference device. Not only does the actual device have the potential to interrupt your beacons signal, but headphones are simply two magnets that create sound waves—more interference!
  • Watch out for magnets. Keep your beacon as far away from any magnets as you can. It may mean picking a jacket that doesn’t have magnets in it, but a different jacket is better than being buried alive.
  • Any electronics you do have keep them far away. A good rule is 30 cm away from any electronics. One source mentioned their recent avalanche rescue course used that number—which seemed to be the median for manufacturer recommendations—as a standard for use.
  • If you are in “search” mode, go out of your way to follow the above. The beacon is even more sensitive to interference when searching.


This winter do everything you can to avoid having to depend on an avalanche beacon save your life—but should you need it, make sure you have the best chance of being located.


Background Sources

Source One

Source Two



Comments (5)

Great Read. I Noticed you only emphasize "search" mode when it comes to interference, but what about the poor guy/girl under the snow with their ipod close enough to their beacon in "transmit" mode. Would it have the same effect as to throw off the readings for the people searching for them?
So I have to put my cell phone in my boot, and my Walkman in my helmet. That way they are 30 cm from my beacon. Not sure if that's practical.
The source from Beacon Reviews as well as mentions on TGR highlighted that it is more sensitive to interference in Search mode, but it would also affect readings when being searched for.
@SpikeDog, the odds aren't exactly a guarantee that devices are going to interfere with them working. But this article is more of an FYI. Everyone should at least know the risks that having devices near their beacon presents and be able to decide which weighs more important for them--having their phone/tunes or optimizing the function of their avy beacon.
As an RF engineer who has worked on technologies that are similar to Avalanche beacon (except to track cool stuff like Satellites and peoples cell phone from an airplane). I think this is a bunch of BS.

If not, there is a simple solution: Take off your go-pro when you are looking for a friend who got caught in an avalanche and throw them in a pack you aren't wearing. (The article says it was the searcher's Go-Pro that messed it up, not the person who was buried).
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