 Poster: A snowHead
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Where are you see that graph?
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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Its on the overview tab of the review, in the "A Note on Wearing an Avalanche Beacon" section, about 20% down the page.
I also like this site beaconreviews.com
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You need to Login to know who's really who.
You need to Login to know who's really who.
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Ahhh, thanks!
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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WOW this is interesting..
quote:
There have been at least two high profile deaths in the last three years because a cell phone interfered with the wearer's beacon. At least one of these cell phones was off.
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You'll need to Register first of course.
You'll need to Register first of course.
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| GlasgowCyclops wrote: |
WOW this is interesting..
quote:
There have been at least two high profile deaths in the last three years because a cell phone interfered with the wearer's beacon. At least one of these cell phones was off. |
Hmm - will have to adjust as I normally store my phone (switched off) in my inside pocket. I guess backpack a safer option. I'd like to understand the rationale behind that though
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Avalanche beacons work by detecting the field lines of the transmitting beacon. Practically any metal will cause a distortion in this field, leading to a reduction in range/accuracy. Any metal should be at least 30cm away from the beacon, as phones, Go-pros, knives, even energy gels packs can be demonstrated to effect the field. Black Diamond heated gloves carry a warning that if the gloves are turned on, detection accuracy may be limited to 50cm. So no electronics, metal or magnetic items.
Taken to its extreme, if you placed your beacon in an earthed ferrous metal box, you would have practically zero range.
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| Quote: |
| Taken to its extreme, if you placed your beacon in an earthed ferrous metal box, you would have practically zero range. |
Not only the range but also the registered distance is affected. The BCA Tracker 2's maximum signal detection distance for a transmitting Mammut Barryvox inside a microwave oven is 7-8 metres but it actually registered that distance as 32 metres.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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| moffatross wrote: |
| Quote: |
| Taken to its extreme, if you placed your beacon in an earthed ferrous metal box, you would have practically zero range. |
Not only the range but also the registered distance is affected. The BCA Tracker 2's maximum signal detection distance for a transmitting Mammut Barryvox inside a microwave oven is 7-8 metres but it actually registered that distance as 32 metres. |
Thank you for that practical demonstration of my comment. Next time I take my microwave into avalanche terrain to make some hot snacks, I'll make sure my Barryvox is not in it 
In all seriousness, it does amaze me the number of people I see with a beacon correctly strapped to their chest, but then place a switched on mobile in a chest pocket, and then a chest mounted Go-Pro with all 3 practically on top of each other.
It is easier to demonstrate interference with a Barryvox, due to the matrix display. Put the Barryvox in send mode, then place a switched on smartphone on top of it. You will probably see a 457 Send Failure message, moving the phone away clears the message. Since most other beacons do not have matrix screens, they are limited in the type of message they can display, so it is not clear that they are being effected.
This is a dedicated Mammut, showing such a failure site: http://www.mammutavalanchesafety.com/2012/10/mammut-pulse-457-send-failure.html
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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I'm very surprised the 3+ came so low down. I find the fine search and multiple burrial features excellent
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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@moffatross, where do you find to plug the microwave in when you are out skiing?
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| PaulC1984 wrote: |
| I'm very surprised the 3+ came so low down. I find the fine search and multiple burrial features excellent |
I find the multiple burial function to be quite buggy. Once I've marked the first victim, direction and distance to the next nearest victim is not as accurate. It gets worse for the third victims and so on. There is a firmware update to fix this but the dealers listed on the Ortovox site who have the hardware to do the update in Chamonix were mystified when I went in to have my 3+ updated.
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You know it makes sense.
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@jbob, haha !! Next time it snows in Moffat, perhaps mrs moffatross will find me burying the microwave in the garden. 
I'd love to understand the phenomenon that makes the signal distance detected drop by a factor of 4x. The box/mesh of the oven is designed to reflect/contain 100% of microwave radiation with a mesh of just a few mm but the wavelength of an avalanche transceiver signal is hundreds of metres long so there'll be a lot of diffraction. How that might affect the reading, I don't know but I guess Haggis_Trap could probably answer that in his professional capacity.
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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I'm no expert but I guess the distance is not triangulated but calculated on signal strength, which is attenuated (weakened) by the mesh.
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Poster: A snowHead
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| moffatross wrote: |
| ... The box/mesh of the oven is designed to reflect/contain 100% of microwave radiation with a mesh of just a few mm but the wavelength of an avalanche transceiver signal is hundreds of metres long so there'll be a lot of diffraction. |
The wavelength and the grating have to be of the same order, from what I recall of my school physics.
So Microwaves don't get through because they're cm and your mesh is mm; radio waves are longer wavelength => there will be less diffraction/ less transmission. It's a Faraday cage.
The other stuff with mobile phones... well you're looking at crosstalk I suppose plus the business of the mobile could cause some trouble I suppose. Real off piste people would be be no where near a cell tower anyway
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FAQ
I think it would be a one time experiment though and as I still use the Barryfox for practice searches, not one I'm likely to perform. 
