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Another Reason to not carry a cell phone while skiing

post #1 of 16
Thread Starter 
I thought everybody should read this.

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Fwd: Avalanche Transceivers & Cell Phones Date: Wed,
21 Feb 2001
Subject: avalanche transceivers and cell phones

Just yesterday I was forwarded a posting from a backcountry skiing
newsgroup. It detailed an accident at a European ski hill
where a skier was buried by an avalanche. He was carrying a digital beacon
and his partner, alone, began an immediate
search using his beacon, but the victim could not be located.
Later investigation revealed that the lone searcher was carrying a mobile
phone and that the phone was turned on. It
interfered with the function of the digital beacon he was carrying and gave
false readings, directing the searcher to an area
approximately fifty metres away from where the victim was buried. The
victim's body was later found using an analogue
beacon, though the article is not clear as to whether or not the phone was
still on and nearby.

A group of manufacturers and distributors conducted tests afterward and
found that analogue and digital beacons are both
somewhat affected by mobile phones. They recommend that all mobile phones
and other electronic devices be turned off
while carrying an avalanche transceiver. Please consider these facts when
using avalanche transceivers.

Regards, Mike
Quality Assurance Manager - Mountain Equipment Co-op

From: Dan D Subject: phones and tranceivers
Date: Tue, 6 Feb 2001 09:22:49 -0700
Digital Avalanche Transceivers affected by mobile phones
A manufacturer's investigation has revealed that the search mode of ARVA
9000 and Ortovox M1 avalanche transceivers
can be affected by mobile phones.

A pisteur died at Pra-Loup on the 25th of December. He was caught and buried
in an avalanche while securing the ski area.
His colleague tried to find him using an ARVA 9000 avalanche transceiver.
The ARVA indicated a direction and distance
that were completely incorrect. 50 meters away from where the pisteur was
buried. He was later found with a classic
analogue ARVA but too late. Inquiries revealed that the searcher's portable
phone was turned on.

The search facility of ARVA 9000 and also the Ortovox M1 can be affected by
mobile phones that are not turned off. After
testing this problem has been confirmed by the manufacturers. It would also
seem that there is some affect on analogue
transceivers. It is recommended that all mobile phones are switched off when
a search is made and it is advisable to turn off
all mobiles while carrying an avalanche transceiver.

CAF Toulouse/Bureaux des Guides Bourg St Maurice
post #2 of 16
Thanks for the info...I use a DTS Tracker, any info on them? I also carry dog treats in my shell, I figure it can't hurt .
post #3 of 16

As I understand it, the problem is related to the signals involved, not the type of transceiver.

These reports have prompted most searchers to adopt a policy of making *certain* that everyone who might be involved in the search turn off their cell phone (if they are carrying one) before beginning the transceiver search.

The potential for interference is significant enough that everyone ought to be aware of it.

post #4 of 16
Since it is so easy for my Nokia to be turned on accidentally by having a button pushed I would probably remove the battery if I were going to carry the phone while skiing (I don't).

This post brings up the question of other devices interfering with beacons. I DO carry a "talkabout" radio. It would be interesting to do some testing of it's affect on beacons before I find out the hardway. Turning off all radios while in search mode would eliminate one of the reasons for carrying a radio. Perhap a disciplined radio check once every 10 minutes or so... But if you're the one under the snow it's a little hard to turn off your radio.

<FONT COLOR="#800080" SIZE="1">[ January 16, 2002 04:09 PM: Message edited 1 time, by PowderJunkie ]</font>
post #5 of 16
The problem described is to do with the transmitted signal being messed up not whether the searching transceiver is digital or analogue.

All transmitting signals are the same whether it is from a digital or analogue transceiver.

Another thing is that the Arva 9000 and M1 are not real digital transceivers. They use a single antenna like all analogue transceivers but use a simple chip to give a more precise indication of signal strength (approximate distance).

True digitals like the Tracker and Red 457 use two receiving antennas to give a signal strength (approximate distance) and direction indicator.

However regardless of the type of transceiver, if the phone is creating a false strong signal away from the victim, any transceiver would give that same indication. The guy who found the victim probably just had a more open mind and ignored the false signal and tried in other areas to find other spikes in the signal.

It was a matter of time and experience searching for a confused transmitting signal, rather than a digital vs analogue search problem.

I do wonder what the phone was doing to the signal though, was the phone transmitting and intefering with the transceiver signal, or was the emf field of the battery and electronics distorting the transmitted signal?

I have oftan carried handheld radios while wearing a transceiver and sometimes when the transceiver is too close the radio will make pulses of static when the transceiver transmits. It should be an important issue for patrollers who nearly always carry both pieces of equipment.

Does anyone have any experience with problems searching for a trancsceiver next to a handheld radio?
post #6 of 16
I think the problem with cell phones is that if they are switched on, they send a location signal at regular intervals so when a call is made to them, the call is routed to the correct cell.
With a two way radio, they only transmit a signal when the talk button is pressed, otherwise they are passively "listening" for other signals.

Don't know if that's the reason, but I know it does cause problems in other areas of life.

post #7 of 16
Cell phones on the hill are just as inappropriate as on a golf course. And dont get me started on those f'ing radios every schmuck seems to carry.
post #8 of 16
Just to perhaps clarify a bit...

The problem is related to the periodic message all cell phones transmit every few seconds to "look for" the nearest cell site. That transmission is what the avalanche transceiver may detect and give a false reading. The only way to eliminate that transmission is for the phone to be completely off.

One of the complicating factors is that it's hard to be calm and thorough when one of your buddies is suddenly covered up with snow. More likely, you're scared s**less and not thinking totally straight.

Knowing in your living room that you should turn off that cell phone before going to search mode doesn't necessarily mean everyone in your party will remember to turn off their cell phones when the chips are down and you're starting the search.

Personally, I solve the problem by leaving the phone off and only turning it on if I need it. Not everyone looks at it that way.

post #9 of 16

<<Cell phones on the hill are just as inappropriate as on a golf course.>>

When you say "on the hill", do you mean in-resort skiing or backcountry skiing?

If you mean backcountry, I think you're wrong. If something goes bad and someone gets buried in an avalanche (or other kinds of injuries), minutes count and the better trained the searchers are the better your chances are.

I do most of my backcountry skiing in the Wasatch Range in Utah. Under the right circumstances, a cell phone call could have a helicopter full of trained searchers (plus avi dog) on the site of an avalanche in less time than most victims die from suffocation.

Having the ability to call in the cavalry - if you need it - only makes sense. It's one more safety tool.

post #10 of 16
Yeah...in area. I can see why you might take a cell phone into the BC (just don't assume it will work in tahoe though...lots of dead spots).
post #11 of 16
And make the phone call then turn the phone off before starting the search...

We could start a whole non-skiing related thread about the appropriatness of cell phones and DRIVING!!!

<FONT COLOR="#800080" SIZE="1">[ January 16, 2002 04:17 PM: Message edited 1 time, by PowderJunkie ]</font>
post #12 of 16

We carry phones into the back country turned off, but never thought of disconnecting the battery -- great idea.

And from what I'm reading, two way radios do not disrupt the beacons, right?

post #13 of 16
In the "Big Picture", cell phones in an emergency situation have saved MANY more lives than they cost. (Not that losing one life because of them is OK).

Since off-piste trees are the preferred terrain of the group of people with whom I ski, I take comfort that most of them have cell phones in addition to radios.
post #14 of 16
let's not forgot these europeans are presumably using GSM cell phones, which interfere with -everything-. I know a second or so before my GSM phone is going to ring, because the speakers in my car will go on the fritz, my computer monitor will distort, and other fun stuff happens. I imagine that a CDMA cell phone might have an effect as well, but not nearly as pronounced of one.
post #15 of 16
Interesting subject!
For time being, i would rely on manufacturer's advise. I do not think GSM vs. CDMA makes a difference.
I checked out the specs of the listed tranceivers. They work on 457 kHz, far away from the frequency bands GSM phones are working (800/900 MHz worldwide/US). If they intefere, CDMA will propably do as well.
post #16 of 16
Aha! Now we might be getting near the reason for the interference, and excuse me if I get the terminology wrong, my memory of frequency nomenclature is pretty bad!
Two of the mobile phone frequencies (I think) are: 900MHz (as mentioned by jpf) and 1900MHz.
457MHz x 2 (i.e. it's first harmonic) = 914MHz. This is kinda close to 900Mhz.
457MHz x 4 (i.e. it's third harmonic) = 1828MHz. Which is reasonably close to 1900Mhz.
So we could end up with signal interference on the harmonics, but becasue they are not an exact match, they would be slightly out of phase which could cause ghost readings on the transceivers that would seem to move.

This might all be wrong, but I think that the closeness of the mobile phone frequencies to the harmonics of the transceivers could explain the problem.

(As for using a mobile while driving: 1. don't. 2. if you must, use a hands free kit. 3. pull over to the side of the road)

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