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Ultra-Small Bluetooth Location Stickers
Posted: 09 January 2013 10:10 PM  
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I wonder what the range through snow will be like. Could be useful for finding lost skis!

http://sticknfind.com/product/

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Posted: 10 January 2013 12:35 AM   [ # 1 ]  
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They are not waterproof! I guess the cold will also affect the battery. Great idea though and I am sure further developments will be in the pipeline. Maybe even a very inexpensive and widely available alternative to the avalanche transceiver?
Also that website is a great portal for product developments - some interesting stuff there.

 
 
Posted: 10 January 2013 12:34 PM   [ # 2 ]  
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I’d want 100% sure hard and fast info that they didn’t interfere with transciever signals before even considering it personally.

 
 
Posted: 11 January 2013 12:19 AM   [ # 3 ]  
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Surely, it’s highly likely they’ll interfere!

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Posted: 11 January 2013 05:21 PM   [ # 4 ]  
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Not professing to be an expert on this but the Bluetooth frequency at about 2.4GHz compared with a transceiver at about 457KHz are miles apart, therefore there should be no interference. In addition, some people carry a myriad of communicating devices these days, such as handheld radios, mobile phones, GPS, car key fobs and even your Mifare tagged lift pass. These all broadcast a radio signal.

 
 
Posted: 11 January 2013 05:52 PM   [ # 5 ]  
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I’m not an expert on this but there’s a couple of things I think make a difference. For example, if I have it right, cell phones aren’t really on the same frequency as transceivers but we know they interfere with receiving transceivers and we know they don’t make a deal of difference more than 30 or 40cm from devices anyway as the signal deteriorates on an inverse square anyway. I *think* interference comes in two flavours one of which is primarily magnetic close up and that’s more generic, the other type if the 2.4Ghz electronic smog our homes have which (as you suggest) probably isn’t relevant here.

So, if you’re buried and the ski ends up bang next to your transceiver there might be a problem but I’m not even sure about that. If your ski is a metre or more away, i.e. still on your feet, I’d say it’s all OK. I’d not want to risk it without testing it first though grin

There’s another project here :  http://www.kickstarter.com/projects/akka/akka-ski-retriever-deep-powder-ski-finder not sure about the claims made there about it being more directional than transceivers.

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Posted: 11 January 2013 07:28 PM   [ # 6 ]  
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All that electronic stuff interferes, but they do need to be close together. Gopro’s are bad and they aren’t supposed to emit anything!

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Posted: 11 January 2013 08:28 PM   [ # 7 ]  
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Contradicting some of my comments - I can substantiate the consensus that no matter what the frequency, there could be interference.
My company uses a low power wireless product known as Zigbee. We use it at 2.4GHz to communicate between a battery powered door handle set (similar to what is often fitted to a Hotel room door) and a Wireless Gateway connected to a PC network. When initially installed and tested in an empty building, it works fine. Once the building is occupied and other systems put in (admittedly some of these will also operate on 2.4GHz), we often have to re-commission our systems, as some units fail to communicate. This sometimes necessitates resiting and/or installing additional Gateways.
As suggested in previous posts, comprehensive testing by an unconnected party would be essential.

 
 
Posted: 11 January 2013 08:38 PM   [ # 8 ]  
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My new avalanche beacon grin.

They say 100’ range. I tested the Loc8tor system which uses the same 2.4GHz frequency with powered RFID and they get 600’ in air. I tested in spring snowpack and got a range of around 20 meters with a transmitter buried under 1.5 meters of snow. That’s similar to a current digital beacon. Of course the transmitter could have a bigger antenna which would give a better range. The 2.4GHz is more directional so you tend to walk straight towards a buried device rather than round a long flux line as is the case with 457KHz which is nice but it is close to the resonant frequency of water so the losses through snow are greater (it is no conincidence that microwaves, which heat the water in food, use a similar frequency).

I can publish a bit more about my Loc8tor experiences. BCA have experimented with this frequency for beacon use in the past but at the last ISSW Franz Kroll of Ortovox said their is no chance of moving off the 457KHz frequency in the near term.

 
 
Posted: 11 January 2013 08:42 PM   [ # 9 ]  
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Here is a video I did a few years back about interference as few people believed it was possible with devices on very different frequencies. The problem is everything radiates harmonics as well as the fundemental frequency although I suspect it is just the switching circuitry and electronics that is giving off the interference.

http://www.youtube.com/watch?v=DVQ4NK63txM

 
 
Posted: 17 January 2013 10:42 AM   [ # 10 ]  
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There’s a recently published piece on transceiver interference here :

http://www.tetongravity.com/blogs/How-Electronics-Interfere-With-Avalanche-Transceivers-6497429.htm

including a video showing a GoPro interfering with a searching transceiver.

Martin

 
 
Posted: 17 January 2013 11:12 AM   [ # 11 ]  
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There’s a couple of good quotes from that :

The video clearly shows that when a GoPro camera is on and in close proximity to a searching avalanche transceiver it can cause interference.

But we know that already and have done for years. It’s not highly original to go and test every device you can think of to prove a premise that’s already proven.

However, Barkhausen did find that within a range of 17 inches, electronic devices will alter the ability for a transceiver to search for a signal properly. Above 17 inches, interference is minimal, but within that distance, problems are persistent

Or, 40cm in metric. We already knew that as well. In fact I said that above grin

Clearly, more study is needed to be able to provide full conclusive data regarding different brands and products that represent the most risk for users.

I can’t see why we need more study. We already understand the science pretty well. You can’t go and test every device combination because that would be impractical and, by definition, you’d never complete the task. You can also reliably predict the result of pretty much every test.

I happened to be out with some guys preparing for their winter IML yesterday and we were messing around a bit with transceivers. I pointed out to them there was a good argument for turning your transceiver on with it stowed in the harness and on your body with all your usual gadgets in the usual places. The reason for this is a device like the Mammut Pulse does a fairly elaborate self check. That check will show up gadgets too close by or generating powerful interference. Or, turn it on holding it where you’re going to search with it. Or, better still, do both from time to time. I appreciate some people aren’t going to be as organised (sad) as me, but I do keep the same stuff in the same pockets and place in my sack all the time.

By and large this isn’t a big deal for anyone. We’re all carrying loads of stuff (me: two phones, gps, camera and sometimes a radio). We talk about going “radio silent” before starting a search but that can be a real pain if things are buried in internal pockets.

But there’s obviously a particular problem with a helmet or chest cam and that’s because it’s on your head and you’ll usually bring your transceiver in search mode to within 40cm of your face to read it*. So, turn it off. Which is a shame, there’s several good reasons to have footage of searches.

* unless you’re a ski tourer and your average age means a) you’ve not got a helmet b) there’s no camera on the helmet you’re not wearing and c) your eyesight isn’t great and you hold everything at arms length to read these days anyway.

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Posted: 17 January 2013 12:21 PM   [ # 12 ]  
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ise - 17 January 2013 11:12 AM

There’s a couple of good quotes from that :

The video clearly shows that when a GoPro camera is on and in close proximity to a searching avalanche transceiver it can cause interference.

But we know that already and have done for years. It’s not highly original to go and test every device you can think of to prove a premise that’s already proven.

Is that info re. GoPros on this website somewhere? The search function only brings up endlessride’s comment above.

Martin

 
 
Posted: 17 January 2013 01:38 PM   [ # 13 ]  
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Maybe I didn’t phrase that brilliantly.

My point was we’ve known for years that devices with their own electromagnetic field do interfere with receiving transceivers if they’re within around 40cm. What I was trying to say is that’s true for a goPro, a phone, another head cam that’s not released until 2014 and so on.

So if someone announces it’s a problem for a new model of contour for example, it’s not really news. I’d just be particularly cautious about helmet or chest cams, because there’s that issue where you’re deliberately moving your transceiver inside that 40cm range.

I’m not an RF engineer but I think the fact transceivers are near-field devices makes them susceptible to this sort of interference. Don’t forgot large things, with big footprints, have an effect beyond 40cm like lift pylons, cables, power lines etc.

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Posted: 17 January 2013 11:02 PM   [ # 14 ]  
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martinday - 17 January 2013 12:21 PM

ise - 17 January 2013 11:12 AM
There’s a couple of good quotes from that :

The video clearly shows that when a GoPro camera is on and in close proximity to a searching avalanche transceiver it can cause interference.

But we know that already and have done for years. It’s not highly original to go and test every device you can think of to prove a premise that’s already proven.

Is that info re. GoPros on this website somewhere? The search function only brings up endlessride’s comment above.

Martin

The search function probably isn’t great. Jake told me about the Go Pro stuff in November 2012

http://pistehors.com/news/forums/viewthread/1335/#4310

and an article from 2004 about Tikka Headlamp

http://pistehors.com/news/ski/comments/transceiver-tikka-masala/

and, as far as I am aware, the article that started this all

http://pistehors.com/news/ski/comments/digital-avalanche-transceivers-affected-by-mobile-phones/