A friend was over at Cooke City with a buddy of his. To sharpen the buddies beacon skills my friend set up a simple single beacon drill and the buddy attempted to locate the buried beacon while using a running Go-Pro camera to record the search and his time.
While the HD camera was running he got strange distance readings and conflicting arrow directions. When he turned off the Go-Pro things cleared right up.
Any thoughts?
Awaiting beta, it matters.
no idea off the top of my head but i'll test this in the beacon park with a few different beacons tomorrow. looking forward to hearing other opinions though
Randy,
What transceiver was he using? And what transmitting transceiver was he searching for? I have no experience or a GOPRO camera on hand to test this.
HM
I wouldn't be surprised at all. I use my Gopro for another hobby of mine which uses wireless video transmission and having the Gopro on nearby significantly reduces the video range and quality. It's known to be quite "dirty" when it comes to electromagnetic interference that it emits.
However, it has only been a problem for me when it’s within about a foot or so of my video transmitter so when it comes to beacons, it might be safe to wear on your head but a chesty mount is probably a bad idea. Although beacons may be much more sensitive to this kind of interference. I’ll try to do some tests with my beacon this weekend.
Maybe a follow up question after this one about gopro is answered, does it also happen with a Contour or other video cams?
I think you've pretty much already conducted a very well-controlled test.Quote:
Originally Posted by Bunion
In general, comprehensive beacon testing ends up becoming a never-ending cycle of repetitive mind-numbing tedium, as it's always possible to coming with new testing configurations to highlight various quirks, and then new firmware versions are always coming out, and results are seldom reproducible 100% of the time which means repeated trials and trying to discern patterns, etc.
By contrast, testing interference with specific combinations of beacons and other electronics devices is pretty straightforward, and you've already done it for this particular combo. I wouldn't be at all surprised though if you find different results with a different beacon and/or different video camera. Plus even in cases of bad interference, just relaxing the proximity a bit would probably help enormously ... although with a helmet-mounted camera, well, the natural reaction to encountering strange readings might be bring your head and beacon even closer to each other thereby exacerbating the situation.
I'm also very grateful to you for bringing this to our attention. In the avy courses I teach, I always stress the importance of maintaining a big distance between a beacon and any smart phone or MP3 player (or preferably keeping them off in the first place). I'd never even though about a POV video camera though, just b/c I don't know anyone who has one. (Pretty amazing, huh?) But the potential to mess up a beacon search, and furthermore be unaware of the cause, is very scary!
I was recently told by an ACMG guide they see this happening with the chesty-mounted newer Hero models and the Mammut digital transceivers specifically.
We saw a lot of anecdotal problems with the iPhone and an older version of the Pieps DSP. Jonathan hits it right on, though. Any electronic device puts out a field that interferes with a beacon- keep them separate and off.
Although I can see, in the future, a mixed-use device that is really just a phone (which is a computer) that transmits and receives, using GPS capabilities.
I think that is a really bad idea:-Quote:
Originally Posted by homemadesalsa
Now which menu and do I go to to turn to search?
Shit, it fell out of the pocket I put it in after that last call.
Damn, the batteries have died because I was using it to phone/take photos/play music.
Keeping essential safety equipment simple is a good idea IMHO. Combining it with a toy (sorry, essential social networking device) is not.
If someone has a GoPro in the Front Range area, I have access to a $2M electromagnetic compliance chamber that we could throw it in and do a quick 2-axis scan to see what bands a GoPro spikes in. PM me.
Through snow?Quote:
Originally Posted by homemadesalsa
Not going to work.
That is pretty rad.Quote:
Originally Posted by coreshot-tourettes
FWIW I just did a search with a tracker 1 and 2 both ways vs. Gopro and only noticed 1 small spike of .1 difference 1 time when I had the tracker 2 touching the Gopro but could not repeat it. I tried with the Gopro a couple feet away and then again right next to the transmitting beacon. Totally non scientific and I claim nothing...take it for what it's worth. Using the last gen Gopro HD...not the newest one.
O.K. some updates now that I have had a chance to talk with the guy involved.
The Search Beacon was a Barryvox Pulse 2 yrs old.
The Go-Pro was the newest model, has the LCD screen on the back.
Symptoms: When searching for the buried beacon (target) a 3-4 yr old Arva there was no signal until the searcher got within about 15 meters of the target. At that point the search beacon would register the target but the distance would vary between 15meters, then 22 meters and then no signal.
Puzzle over that.
FWIW, the instructors for my avalanche L1 course this weekend advised that any device with a microphone (e.g., an iPhone or POV camera) should be kept a minimum of 30cm from your beacon.
Interference is interference... that's sort of how it works. no sort of consistency.Quote:
Originally Posted by Bunion
Probably a good rule of thumb. I doubt this is actually limited to devices with microphones though... It's likely that switching power converters are the culprit in generating the interference, both because of the frequency involved, and the fact that those circuits have a tendency to be noisy. So anything with one of those circuits in it has a possibility to generate interference. This would include almost all digital devices. Even headlamps commonly use "pulse width modulation" for dimming (where the LED gets shut on and off quickly, generating a kind of strobe-light effect), and it wouldn't surprise me if one of those was enough to throw off a beacon.Quote:
Originally Posted by McCorduroy
Dammit my beacon won't work near the microwave either. POS! I'll post it for sale in Gear Swap for anyone interested. I'm switching to an airbag pack now.
Or perhaps you found your wavelength on the signal? I'm assuming as these beacons are low frequency they will have a longer wavelengthQuote:
Originally Posted by Bunion
I know F-all about beacons, well, but a little about electronics. I have an analog beacon (F1). Since it's analog, it should pick up interference as an audible signal, and it does. By playing around with it in my house, I can verify that various electronic devices cause static on it. Most of the time this is a low background hiss, but if you get something close to the beacon, it can be quite loud. The AC power brick for my laptop causes a large amount of interference (more than the laptop itself), which confirms what you suggest. Switching power supplies are known to cause a lot of RF noise. My cellphone causes a little noise but if I do something to wake it up and ping the tower, there is a noise spike. An LED headlamp wasn't too bad. A camera caused a little noise, I didn't try running it in video mode. Interference is unpredictable, so two different camera models could easily differ by a lot.Quote:
Originally Posted by NatEE
This is analog so I just hear static hiss. I wouldn't be surprised if strong static caused digital signal processing to behave oddly.
Interference falls off fairly rapidly with distance from the device. I suspect that the offending Gopro was on a chest mount rather than head?
Bottom line is sort of common sense: I don't think you want an active electronic doodad (Gopro, ipod, cellphone, ...) close to the RECEIVING beacon.
Did this ever happen?Quote:
Originally Posted by coreshot-tourettes
Coldfeet's comments above mesh really well with this report from Beacon Reviews http://beaconreviews.com/transceivers/Interference.asp
Upshot - any device that emits an electromagnetic field (i.e. anything that requires an electrical current) can potentially interfere with a beacon's reception. Distance between devices seems to matter a lot.
I've done practice searches with/without my iPhone playing music and have only had a problem once - which was enough to spook me. Better to keep them off when traveling in avy terrain - you can always turn them on for GPS, recording observations, doing a naked snow dance to Ullr or whatever.
Thanks so much for posting this. Another great reminder to enforce with our touring partners to keep their electronics off and/or well away from your chest while touring.
It's too easy to say "yeah, well it's only a problem while I'm searching, so I can have this iPod or GPS or SPOT in tracking mode banging away for now and keep it in my convenient chest pocket and turn it off later," when in reality, you won't remember to turn it off later, and that is going to be the last thing on your mind if your friend is somewhere down below and all you see is a big debris field.
BUMP
for truth, relevance, thread police
(Without testing this out) the short answer is, no, not all "signals" are a good thing and certain DSPs can become overwhelmed or screwed up.Quote:
Originally Posted by rmnpsplitter from the "Video - Tahoe Skier Burial" thread
The way the avalanche transceiver system works is like this:
- A transmitting device emits a near field magnetic wave on 457 kHz with a regular pattern. This is our target signal.
- A receiving device has 1, 2, or 3 antennas tuned to 457 kHz to attempt to receive this signal
- The information from each of the antennas is processed by a digital signal processor (DSP) to discriminate the difference between signal and noise (random electrical information detected on that antenna), and also to interpolate the information from each antenna to determine the direction of the field line and approximate distance of the transmitting device (given an expected field strength of signal)
- Some DSPs, which are highly sensitive or asked to do processing for secondary purposes, can become confused or overwhelmed by certain noise that is difficult to discriminate from signal
- Electronic device power supplies and processors create local electromagnetic noise radiated locally - the device does not need to have an RF transmitting chip (radio, GPS, wifi, bluetooth) to create noise!
- In the worst case, the code in a DSP can become so overwhelmed by confusing noise that is not a proper signal, that it can lock up or reboot the firmware in the avalanche transceiver (thank goodness for watchdog timers)
- Again, if the signal to noise ratio becomes compromised, then not all electromagnetic radiation generated from the buried subject's body will be of assistance to the searcher
Bottom line:
-not all "signals" are good or equal
-keep running electronics at least 30cm away from a transceiver (and only if necessary to use them)
further thoughts
-I think it's time for avalanche transceiver designers to create standard test procedures around use near consumer electronic devices ... triple check watchdog timers and isolate processing (hopefully the receiving DSP is on a different chip than the one which controls LED/LCD readouts and master state machine etc)
-unfortunately since we are stuck with 457 kHz as the standard and I don't really see this situation improving due to proliferation of switching DC-DC power converters, high frequency processors and other advanced (noisy) elements in our consumer devices
-most consumers will NOT think to expect interference problems with helmet cams and cell phones ... the industry should campaign to do something similar to aircraft takeoff and landing (shut off all electronics?)
Quote:
Originally Posted by SchralphMacchio
Thanks for the breakdown and the info! I'm not EE and really a tech jong. I know enough about beacons (following the signal arcs) to use one and how to perform a proper search with one but that's where the line is drawn. I should prob have a better knowledge of exactly how it works.
^ True that, but the easier answer to that inquiry is that the interference is with the searching beacon, not the transmitting beacon.
(So if you care only about yourself, might as well film all your runs with a POV and simultaneously be uploading them to your FB page, since it probably won't affect how quickly you're found ... even if all your gadgets will produce all sorts of weird false signals when you are searching for someone else. And if your partners are the Echo Peak crew, might as well add in some sort of music player, since you'll be waiting for awhile. BTW, the burial victim has now publicly posted his account, although it provides no new information, other than that he was the only one who sort of knew what he was doing.)
Sent from my ADR6300 using TGR Forums
^ not a good thing if the buried victim's GoPro reboots the searcher's DSP inside of 2 meters!
I haven't seen a documented case recently, and as I said in the other thread, my hypothesis is that the signal to noise ratio of a buried transceiver next to a buried GoPro is likely to be interpreted without issue by the searching device, but there is always a chance for weird behavior that can derail the searcher.
Quote:
Originally Posted by Jonathan S.
What I was getting at is that if you are the skier that is buried and you have a go pro it would cause interference with the people searching for you and whether this would give them problems accurately locating you. If I was the person doing the searching I wouldn't want to have my go pro filming it anyways. Not something I would want to go back and watch. That being said I rarely use or even carry my go pro, mostly just take stills with my digital camera. The phone and gps are good ones to remember because I do usually carry them in my snowpants pockets for emergency use (phone) and to track my hiking speed (gps). But as others said just keep it off and in the pack until its needed and problem solved right?
'Cept the FCC (and various members of Congress) have been leaning on the FAA and their shifting justifications for the electronics rule because, per a number of different tests, the interference issue isn't an issue in that case. So not a perfect analogy, but yeah. :)Quote:
Originally Posted by SchralphMacchio
Beacon reads EM flux lines. Other EM devices alter those flux lines.
I turn everything off in avy terrain.
Fixed it for you. I'm being pedantic for sure ... But beating a dead horse:Quote:
Originally Posted by djrez4
An electronic device does NOT need to have a radio to interfere with an avalanche transceiver. The interference is caused by standard components such as the power supply. This means iPods can cause just as much problems as iPhones.
Thanks for the fix.
What the Schmarate Kid said - any flow of electricity creates a magnetic field that can alter flux lines. There don't have to be any transmitters. iPods count; so do GoPros.
I tried to find a more general beacon interference thread than this one.... But couldn't.
I'm using a Mammut Element right now. I have it in search mode often and it is surprisingly good beacon for the price. Just as good as a Peips DSP it seems to me.
Anyway. I carry a metal crystal screen in my pocket. Don't give me a hard time - it is part of my volunteer "job", and having useful tools handy makes them useful and fast to use whilst always on the move.
All my right hand side jacket pockets have had zips blow out and I had to sew them all shut. I'm poor. So I briefly started to carry my stuff in my left hand jacket pockets, right over my beacon.
On a pretty regular basis the crystal screen causes the Element to beep with an E3 error: "Failure to transmit". It says as much on page 27 of their manual, so I have no gripe with the beacon - it performs as advertised.
http://issuu.com/mammut/docs/1210_el...emanual_web_en
Just worth pointing out that reading the manual is worth while. And so to is keeping metal objects away from your transceiver.
I need a damned pocket sponsor!
^ that's pretty awesome that the circuitry can detect standing wave reflections or whatever the hell it is detecting while in transmit mode. Makes me almost want to by a Mammut. Almost.
Hero 3 both has WiFi built in....this could be a huge issue and effectivly make having a GoPro on during a decent (particulalry a hero 3 or other hero with WiFi backpack) could render your beacon essentially useless....I am not a electrical engineer but certainly more needs to be investgated. I'll be sending a e-mail to GoPro....shortly asking for any data on electromagnetic interference with avalanche beacons. If anyone can test the unit independantly to verify it would be valuable information....probably some emails to Beacon manufacturers is in order as welll.....
The interwebs is a vast repository if knowlege....
WiFi Interference
http://en.wikipedia.org/wiki/Electromagnetic_interference_at_2.4_GHz
Avalance Beacon Interference
http://beaconreviews.com/transceivers/Interference.asp
GoPro Hero 3 has a WiFi remote and the ability to send streaming live preview video to a smartphone running software....I woulds assume for it to do this it has special circuits to handle the transmission of video...this chips can create a significantly higher amount amount of electro magnetic interference as it would be similiar to running a Roku or other wireless video tramsmission device in the home....
Here is a tear down of a GoPro Hero 3
http://connect.dpreview.com/post/477...wn-gopro-hero3
This issue is huge....if a GoPro interferes with a successful recovery of a buried victim that would be a huge needless tragedy...
More on Ambarella Chip Cameras
http://www.ambarella.com/products/co...d-cameras.html
Hero 3 is a known offender, FYI.
Once again, to beat a dead horse. Not caused specifically by the Wifi chip, but the processing on the device in general. So, a Delorme GPS with advanced functions can be just as bad ...
I am going to apologize in advance, this may be a stupid question.... does a techy watch like a Suunto with gps and all the other things it does have an impact on a beacon search?
The new H3 has a WiFi option. I bet if it's turned off then there'd be no interference.