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.
When searching, your consumer electronics (e.g., phones, cameras, headlamps, heated gloves, music players, etc) need to be further away from your transceiver than when transmitting—transceivers are much more susceptible to interference when in search mode. (These devices haven't been shown to interfere with a beacon's transmissions.)
As a rule of thumb, you should keep your electronics at least 50 cm (20 inches) from your avalanche transceiver when searching. And if you are on a call on cell phone, it should be
much further away—25
meters or more.
To be even safer, turn your electronic devices off anytime you are searching (which is what most manufactures suggest). And since this would be easy to overlook during the inevitable panic of a real rescue, it best to turn them off before you enter avalanche terrain.
Here are some of the manufactures' recommendations:
The Tracker3 and Tracker S manuals recommend at least 50cm (20 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).
ARVA and Mammut say electronic devices should be kept at least 50 cm (20 inches) from other electronics.
It is preferable to turn your electronics off when
transmitting so you don't forget to turn them off (or move them further away) when searching. If you choose to keep your electronics turned on when transmitting, keep them at least 20 cm (8 inches) from your avalanche transceiver. Although the actual distance where your electronics will interfere with your transmitting beacon is less than 20 cm, you don't want the items to get within a few inches, or touch, your avalanche transceiver if you are tumbled in an avalanche. For example, you wouldn't want your transceiver harness to shift in such a manner that your transceiver is touching a radio in a chest harness.
Metal can partially block a beacon's
transmission. In our testing, we discovered that something as seemingly innocuous as a few Gu gel packs (which contain metal sandwiched in between plastic layers) can drastically shorten a beacon's transmission range. Don't keep any suspected metallic layers in a clothing pocket that might overlap your transceiver. Likewise, don't allow your cell phone, pocket knife, or two-way radio to get within a few inches of your transceiver—even when transmitting.
A few avalanche transceivers, including several ARVA transceivers (including the
Neo Pro) and the Mammut
Barryvoxes, will recommend a narrower
search strip if they sense interference. For example, the Barryvox will display "20m" if it detects interference or that the transmitting beacon is transmitting outside the standard frequency.
All of the Pieps transceivers that were released after 2013 have a feature where they will
transmit on the shorter (i.e., x-axis) antenna if the transceiver senses interference with other electronics (e.g., a cell phone) or if there is damage to the primary (i.e., y-axis) antenna. You can test this by waking up your phone (you don't need to be on a call) and holding it against the transceiver as shown in this picture. The display will then show that the shorter antenna is transmitting.
transceiver comparison table has rows that show which transceivers adjust the search strip and transmitting antennas based on interference.
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. And as mentioned above, don't let your cell phone get within an inch or two of your transceiver even if your cell phone is turned off—it's still metal.
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."
Here's some irony: when a Pieps transceiver is in
search mode, it can interfere with other
searching transceivers that are within one or two meters. This can result in the other transceivers not receiving a signal.
This is most noticeable when the searching transceiver is near its maximum reception range. As soon as the searchers move at least two meters apart (e.g., they begin their
signal search) the interference will no longer affect the search.
This is primarily a concern when testing the reception range of transceivers (i.e., when two or more searching transceivers are very close to each other and near their maximum reception range). This shouldn't be a concern during an actual rescue.
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.
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'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 heated gloves is one more thing you'll need to remember should calamity strike.
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, and maybe the
Barryvox S). 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.
Several transceiver manufactures mention that people with heart pacemakers should "follow the pacemaker manufacture's recommendations" and suggest that people with pacemakers should wear transceivers on the
right side of their body.