Paging Jonathan..... Go-Pro camera interfering with beacon search?

[SchralphMacchio]

My question is, for people who have tested this out, the intereference that is caused by other electronics on a buried victim cause the beacon to pick up other signals from the electromagnetic field of the device right? Does this screw with how the beacon measures the distance (digital beacons) to the buried victim? In other words would it tell you that the person is closer or further away than they actually are? Seems like if it just picks up an extra signal that it would only really be an issue if the person lost a pack with the device in it causing the interference and leading the rescuer away from the buried victims location. In other words, arent all signals leading to a buried person a good thing whether it comes from their beacon or another electronic device? Or have I missed the boat completely?

(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.

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?)

[rmnpsplitter]

(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.

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?)

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.

[Jonathan S.]

^ 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

[SchralphMacchio]

^ 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.

[rmnpsplitter]

^ 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

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?

[LightRanger]

the industry should campaign to do something similar to aircraft takeoff and landing (shut off all electronics?)

'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.

[djrez4]

Beacon reads EM flux lines. Other EM devices alter those flux lines.

I turn everything off in avy terrain.

[SchralphMacchio]

Beacon reads EM flux lines. Other ELECTRONIC 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:
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.

[djrez4]

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.

[neck beard]

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!

[SchralphMacchio]

^ 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.

[oldbastard]

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

[SchralphMacchio]

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 ...

[snowgod5]

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?

[CupoDamus]

The new H3 has a WiFi option. I bet if it's turned off then there'd be no interference.

[bertrenolds]

The new H3 has a WiFi option. I bet if it's turned off then there'd be no interference.

This is good to know with the hero 3, is there an option to turn off the wifi? Has anyone sent gobro an email about this?

[TBS]

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?

Does it run on electricity - from batteries, solar, extension cord to wind turbine? If so, then YES, it MIGHT mess up your ability to pick up a buried beacon.

Again, as stated several times in this thread, any device that uses electricity - GPS, iPod, digital camera, headlamp, smartphone, laptop, sex toys - has the potential to interfere with your beacon. The issue has nothing to do with WiFi capability and everything to do with the power consumed by the other devices, the distance between devices, and the frequency of the stray signals.

The level of interference has an inverse-square relationship with distance, so holding your beacon with the same hand that your Suunto hangs from will magnify the likelihood of interference. OTOH, the power used to run the watch may not be enough to create much in the way of stray signal. The frequency of the watch's emissions may not be close enough to the 457kh frequency of the beacon to impact the search either.

Only one way to tell for sure - get a fix on a transmitting beacon, then move your Dick Tracy watch/gps/communicator/etc toward your searching beacon and see if the tracking goes wacky. Would be interesting to hear your findings.

[TBS]

The new H3 has a WiFi option. I bet if it's turned off then there'd be no interference.

This is good to know with the hero 3, is there an option to turn off the wifi? Has anyone sent gobro an email about this?

Have the two of you been paying attention? Did you read Shralp's explanations above? Beacon interference has nothing to do with the presence of a wifi signal!

If stupidity emitted an electronic field, the two of you wouldn't be allowed within 100 KM of a transmitting beacon.

[spook]

has anybody seen a skull that looks like a tibia fibula?

[NatEE]

(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.

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)

This point got me thinking... Beacons have the CE mark on there, which probably means they are subject to the European standards for EMC/EMI, which are usually fairly robust (FCC by comparison generally only regulates noise emission not noise immunity). It turns out there already are a fairly comprehensive looking set of standards.

Unfortunately there's a lot of tedious digging involved to get at all the particulars in there, but from first glance it looks like there is at least a requirement to meet some type of "immunity" test- meaning the device gets placed in a lab, bombarded with a known amount of noise and has to operate through it. Usually in order to pass these tests products have to be fairly well designed in terms of shielding, filtering and other noise considerations.

That noise interferes with a search and produces incorrect search readings is unavoidable, however, IMO, noise should not cause a beacon to "reset", go nuts, or otherwise have issues outside of the poor search readings. If beacons are doing that, reports and pressure on the manufacturer to improve designs is warranted.

[SchralphMacchio]

That noise interferes with a search and produces incorrect search readings is unavoidable, however, IMO, noise should not cause a beacon to "reset", go nuts, or otherwise have issues outside of the poor search readings. If beacons are doing that, reports and pressure on the manufacturer to improve designs is warranted.

Ding ding ding. I am talking industry standards here ... perhaps even a new class of UL product with agreed upon test procedures written by consortium.

Disclaimer: as an industry outsider, I have ZERO knowledge or visibility into existing, or planned, test standards, proprietary or universal, that apply to these products. I am unaware of any developments within ISO / IEC / CE / UL / IEEE to create/adopt universal standards for operation and frequency protection, but this would be the path forward.

The CE logo could be little more than indicating safe use of power circuitry, trace spacing on the circuit board, etc and nothing about the transceiving operation of the unit. To their credit, BCA and Ortovox actually publishes that they are compliant with EN 300 718, one of the three standards linked on NatEE's link above. I don't know if every manufacturer has adopted this, and it is certainly not a required marking on the device, and does not appear to be a common marketing-driven marking on webpages or packaging. So ... the standards do not have *that* much weight yet, or else we'd know more about them as technical consumers.

If we had anyone here with NatEE's background, and other product development leaders, we could certainly write a joint letter to be sent to BCA, Mammut, Ortovox, PIEPS, etc ... but ultimately it's going to take consumer pressure and interaction with leaders from each of these corporations to drive more transparency and better data. I don't know if ISSW is the forum to motivate updated progress from the industry, but I can't think of a more relevant convention at the moment.