Pieps DSP - (apparently) iPhone related failure mode

[Jonathan S.]

Hey Jonathan, did you mean iPod or iPhone?

By iPod I meant . . . iPod.

[Tye 1on]

Interesting Suit. Does 'airplane mode' kick off all of the browser and text message functions too? My last two phones, a flip and a crackberry, both seem to send some interference, sort of a tone, through my work phone if they are close together.

Regardless, I think my take home lesson is to keep the phone turned 'off' while skiing, checking messages at the bottom/lodge if need be...That way the lesson isn't to not buy an iPhone!

[SchralphMacchio]

This is an informative thread.

I was taking an avalanche safety class with a guy this last weekend, and noticed the beeping randomly coming from his PIEPS DSP transceiver as well. We were all stumped by it, but this explanation is very likely applicable.

Great research Suit. People should understand that high-frequency communications can cause localized EMF near circuit boards containing computing circuits. You don't need an antenna because the components and traces in the circuit boards will generate the electromagnetic flux. I never would have suspected that this EMF would trip up an avalanche transceiver, but the PIEPS DSP is very sensitive. In our range tests this last weekend, the PIEPS was consistently among the receivers that could get a signal the furthest from the target transceiver.

[MakersTeleMark]

Another data point: My S1 HATES interference.

[g.rosen]

I was taking an avalanche safety class with a guy this last weekend, and noticed the beeping randomly coming from his PIEPS DSP transceiver as well. We were all stumped by it, but this explanation is very likely applicable.

Hi Alex. Thanks for the "heads-up." I just tested my Pieps (current model - version 5.0 firmware) and found some interesting results. After multiple tests, I consistently got the E04 error message about 3 seconds after placing my cell phone (t-mobile GSM) on top of the transciever in the "send" mode. However, I could not re-create the beeping we heard. I also found something that could be equally disturbing in the field. In the search mode, if I brought the pieps within 6 inches or so of the cell phone, it would register multiple burials. For both tests the cell phone was turned on, but I was not making or receiving calls.

[Wolfmansbro]

has anyone had these results replicated with other beacons?

[Jonathan S.]

Over the past year I've tested all the beacons on the market for cell phone interference . . . but with a CDMA phone, not GSM.

[Bunion 2020]

X-post and I am not him.

http://www.telemarktalk.com/phpBB/viewtopic.php?t=42207

I recently updated the http://BeaconReviews.com website.

The updates include a new review of the Ortovox S1, an updated comparison table, retesting of the multiple burial features of the ARVAs, Pieps DSP, Barryvox Pulse, and Ortovox S1, and testing of the Pieps DSP using the latest software update (version 5.0). I also updated of the range chart, added a new page with 20 online users’ manuals, added more avalanche news (updated ~daily), added more information regarding cell phones and electronic interference, and added preliminary information on the Pieps Freeride transceiver, the Pieps iProbe, and the Tracker 2.

Steve
BeaconReviews.com

[Arty50]

By iPod I meant . . . iPod.

Sorry, I just wanted to make sure. The gadget freak in me was like noooooooooooooooooooo.....

I should note that I never tour with my iPod, and for similar reasons I almost never mountain bike with it either. I just think being able to hear is too important in both of those activities since your partners are your safety net and vice versa. So far, I've only used my iPod inbounds; but I do beep inbounds often too. They day I rode an inbounds slide at Kirkwood was a wake up call.

So, it looks like when I'm beeping I'll be leaving my iPod in the car and keeping the cell turned off. Thanks for all of the info, everyone. This is a great thread.

FYI, I have a DSP.

[The Suit]

Sorry to be coming up with data piecemeal. I really need to do some systematic testing.

Anyway, I've found that I can make a DSP return the "E04" error code simply by holding it directly next to a piece of metal. I'm not sure if ferrous/non-ferrous makes a difference.

However, I've also found that even though the indicator LED stops flashing while the beacon shows "E04" it is nonetheless still transmitting and therefore searchable. So maybe my worries are somewhat overblown.

I really need to test to track down the "rebooting" behavior. I've now seen that with three different units, apparently triggered by an iPhone and by a handheld radio.

[smolakian]

Over the past year I've tested all the beacons on the market for cell phone interference . . . but with a CDMA phone, not GSM.

I think the real point to take away from this discuassion is, like Suit said, any electronic device has the potential to interfere with your beacon.

The fact that the devices in question (cellphones) are transmitter/recievers, I think may be besides the point. Cellphone communications are carried in the hundred of MHz range while beacons operate at 457 kHz.

Most battery powered devices that you might carry with you in the BC are probably using SMPS (switching power supplies)...including your beacon. SMPS are extremely power efficient. The nature of the way switching regulators work causes more EM "noise" to be generated. The frequency of the regulator is gonna effect the nature of the radaited emissions (current switching on and off through a conductor causing EM at specific frequencies) I am just using the regulator as an example. An oscillator (clock for a microprocessor etc...) or some other component may also cause EMI.

I know it is confusing stuff, but you can think of it this way if you remember a little bit from physics class:
Think of a trace (you can think of it as a wire if you dont know what a PCB trace is) in your electronic device in question just like your beacon transmitter. When an electric current passes through it an electromagnetic field is generated. (remember electromagnets) The field is exactly what the flux lines are that you follow when doing a search. It also works in reverse: Wires, traces or any other conductor in an electronic device can be effected by these electromagnetic fields coming from somewhere else. this can cause voltage and current to appear where ther shouldn't be any. (Thus causing errors,glitches,noise or possible failure)

All of this stuff is completely design dependant and quality compliant devices should be using good design techniques to eliminate or reduce the amount of EM radiation that escapes the device AND also to mitigate the effects that EM from the outisde world effects any sensitive electronics (say the Analog to digital converter in your beacon).

The short answer:
Long range signals from a beacon/cellphone/radio should be clean. But, electronics do not need an antenna or transmitter to create their own meaningless signals. Those "noisy" signals are what they test for and if there are any, they should be very low power. So, as long as any other devices aren't kept next to, or very close to, your beacon stray EM shouldn't be reaching it (unless the device is very noisy). If your beacon and cellphone/radio/gps aren't total pieces of crap, they should not be leaking stray noise out of their transmitting bandwith. So you should be able to sefely leave them on.

Of course, there are TONS of variables and other issues to consider (EMI/EMC is a nuanced subject). So, I may be missing a piece. But, that's pretty much my feelings on the subject of beacon/cellphone interference.

[sethschmautz]

Hey Suit, That piece of metal that you put your DSP up against wasn't an aluminum shovel blade, was it? I can't think of any time when my beacon (a Pulse) would be transmitting and up against my shovel, but that is probably the largest piece of metal that any BC skier would be carrying on them. Any idea if any shielding occurs if said aluminum shovel is between your beacon and your rescue party?

[pechelman]

This is just a really random off the wall idea here, but having a good amount of exposure to EMI\EMC sensitive items and designing RF barriers and such, it might be interesting to design a "Dead Zone" pocket in your jacket or pants to place items such as cell phones or iPods. One negative side effect though is that whatever inside the pocket would not be able to get an outside signal, ie cellphone, but it would not effect items such as an Ipod, where you only care about the signal coming out of the headphone jack.

Essentially all that would have to be done, is to line a pocket with a fine metal mesh.
Probably add about 1-3grams to the weight of any garment, pack, or item.
as seen here
http://www.lessemf.com/fabric.html

[Telenater]

I'll confirm that my iPhone produces enough interference that it's detectible by my beacon (Early model Tracker DTS) in search mode from about 1m away in both airplane and nonairplane modes. By detect I mean that the Tracker flashes and say that there was something at some distance. The displayed distance appears to be unrelated to the real distance of the iPhone. This is particularly noticeable if the phone is rotated in relation to the beacon (ie you change the axis of the flux lines in relation to the beacon).

I have no evidence that it interferes with the beacon in transmit mode, but it's not something I particularly want to test under real world conditions.

[straight outta sultan]

Friend of mine could make his DSP turn on or off just by placing a motorola 2-way radio near it. Anybody else tried 2-way radio interference w/ the Pieps or had similar results?

[The Suit]

Friend of mine could make his DSP turn on or off just by placing a motorola 2-way radio near it. Anybody else tried 2-way radio interference w/ the Pieps or had similar results?

Mine rebooted once when the only electronic device near it was a handheld 2-way radio. It was not transmitting at the time.

I was cleaning up dog shit when it happened, so I didn't pay a lot of attention to the details.

[powslut]

Interesting comments put on the skiinggolden.com website regarding magnetic interference and digital transcievers. I guess a heli and cat skiing operations are starting to not allow jackets with magnetic clasps in them.

http://www.skiinggoldenforums.com/viewtopic.php?t=74

[smolakian]

This is just a really random off the wall idea here, but having a good amount of exposure to EMI\EMC sensitive items and designing RF barriers and such, it might be interesting to design a "Dead Zone" pocket in your jacket or pants to place items such as cell phones or iPods. One negative side effect though is that whatever inside the pocket would not be able to get an outside signal, ie cellphone, but it would not effect items such as an Ipod, where you only care about the signal coming out of the headphone jack.

Essentially all that would have to be done, is to line a pocket with a fine metal mesh.
Probably add about 1-3grams to the weight of any garment, pack, or item.
as seen here
http://www.lessemf.com/fabric.html

Yeah an iPod pocket with a faraday cage!
Or, you could just turn them off. Blasting tunes while you're skiing in the backcountry probably isn't that wise anyway.

[JayTurcot]

*bump*

Just gonna boost this up in hopes that any new TGR readers who missed it the first time see it.

Just did my AST-1 and if it weren't for an email forward I got from a buddy (which I came to confirm on TGR) I would never have known.
iPod for the long tours was on my Xmas wish list. Scratch that.

[khyber.pass]

hey folks, yes, cell phone should be OFF when beacon is ON. Interesting to see that this rule of thumb is not as widespread as I thought.

As for a Faraday cage for the iPod, all you have to do is wrap it in tinfoil (same goes for anything with RFID, btw, such as new passports and some IDs, if you want to avoid being tracked).

As for 2-ways, it's a pain as they appear to interfere periodically with digital beacons. I'll ask some patrol colleagues what they do.

[sfotex]

Interesting comments put on the skiinggolden.com website regarding magnetic interference and digital transcievers. I guess a heli and cat skiing operations are starting to not allow jackets with magnetic clasps in them.

http://www.skiinggoldenforums.com/viewtopic.php?t=74

It's not interference - the dps (and pulse,opto 3000 and other's I'm sure) use a magnetic switch to turn them on and off. You can take 2 beacons and use them to turn each other on and off w/o moving the switches..

From the Mammut site:


My Opto3000 can be turned off using the magnetic buttons of my jacket. Why is this possible?

An avalanche transceiver must be 100% waterproof. This requires the use of a special on/off switch. The Opto 3000 has a magnetic switch. It is waterproof and maintenance-free; however, other magnets may interfere with its function. Therefore, we highly recommend refraining from the use of clothing with integrated magnets if you are using an avalanche transceiver at the same time.

[Jonathan S.]

- Update: ran some tests with an iPhone today. When held close to a searching beacon, interference (in S1, DSP, Pulse) was far worse than other previously tested devices. (Finding the target beacon would have been essentially impossible were the iPhone to have been kept immediately adjacent to the searching beacon.)

– When I asked a member of my patrol who is both an electrical engineer and an NSP avy instructor, he thought it was all the internal processing and maybe also the power convertor, and not the actual cell transmission.

- So basically like this quote from earlier in the thread (if I'm understanding it correctly, which I might very well not be):

Most battery powered devices that you might carry with you in the BC are probably using SMPS (switching power supplies)...including your beacon. SMPS are extremely power efficient. The nature of the way switching regulators work causes more EM "noise" to be generated. The frequency of the regulator is gonna effect the nature of the radaited emissions (current switching on and off through a conductor causing EM at specific frequencies) I am just using the regulator as an example. An oscillator (clock for a microprocessor etc...) or some other component may also cause EMI.

[sparkletarte.]

Thanks for the great website Steve.

I have a Burton jacket with magnet closures, and I use an SOS analog beacon. I was told that it was only the Barryvox beacons that were affected by the magnets, but it sounds like all of the digital ones are. I'm looking at getting a new one. I don't really want to cut the magnets out but it sounds like I will have to if I do get a new one. Can anyone clarify the Pulse changing from digital to analog? I see that you can manually set it to analog- would this eliminate the magnet issue and/or would it cause other problems in using it (not being able to take advantage of its digital features)?

Some friends that work at a cat operation here that uses Burton jackets said they cut them all out of their staff jackets. I find it irresponsible of Burton (or whoever makes jackets with magnets) to not include info about this with their gear- yet they include a note about not listening to loud music when you ride. I had no idea when I bought the jacket.

[Jonathan S.]

Can anyone clarify the Pulse changing from digital to analog?

My attempt (from my upcoming review) follows below.

****
Alternatively, the Pulse can be switched over into an “Analog” backup mode, whose exact behavior depends on user programming. I put “Analog” in quotes because with a 180-degree rotating arrow and no spikes/nulls in the pinpointing phase, the Pulse is still using all three of its antennas and digital processing: the difference is that the signal separation and hence marking/masking is turned off, as well as the forward/backwards capability of the rotating arrow. Combined with full sensitivity control and even a multiple-burial indicator, even if the Pulse had only this backup mode and not its regular mode, its design would be an impressive technological accomplishment. The Pulse can also be switched into a pure analog mode that shuts down the display entirely and receives on only one antenna.

If the preceding paragraph is completely overwhelming to you, then rest assured that you need never use “Analog” mode or ever be concerned about it.

[Bunion 2020]

A couple of things.

1. I will be selling my DSP ASAP. After another blown double search today, I have had it. The processor doesn't keep up fast enough for my taste. I have never felt 100% with this beacon and I need to feel sure about a lifesaving tool.

It is a 2 yr old unit with upgraded software. The mark/isolate function seems flukey and today while standing still, the numeric dispay was all over the place. From 62 to 67 and back again w/o changing orientation.

2. I will be ordering a new Ortovox F1.
I had one before I had my Tracker and my DSP. It was solid and reliable.

3. I now want my patrollers to leave their cell phones at our PHQ before beginning A/C routes. The risk of a problem/interference is not worth it.

Back to analog. Yippee!