Phone Faraday

[total_immortal]

Came across this product today.

https://www.tightchutes.com/product-page/phone-faraday

It's a faraday cage for you phone to stop interference with your beacon. Any of you techies have any insight if this is worthwhile or just a gimmick?

[Core Shot]

I use one when scoring fentanyl.
And visiting my mistress.

[dunfree]

You can get soft faraday phone cages for $10 from Amazon.

[nickinbc]

Well if it works as a truly effective Faraday cage you might as well turn the phone off. Save the cost of buying it and make your battery last longer.

[Ørion]

Well if it works as a truly effective Faraday cage you might as well turn the phone off. Save the cost of buying it and make your battery last longer.

Devil's advocate, but for those that use their phone for pics and GPS enabled maps, it would be helpful to be able to pop it out of the Faraday bag and have it already booted up. Battery loss would be minimal if the phone is already in airplane mode.

[TBS]

Anything that creates an electrical field - phone, GoPro, vape - can interfere with a beacon’s reception.

[lucknau]

Unless it is solidly grounded, I don’t think a Faraday cage will stop electromagnetic radiation. It will disrupt the signal to and from the device inside, but the signal originating from inside the bag will still have to dissipate atmospherically, and thus have some potential to mess with the beacon signal. It’s more useful as a security measure than anything else. I’m shooting from the hip, though. RF isn’t my specific area of expertise. Would be cool if someone could get ahold of a spectrum analyzer and run some experiments.

Edit: I just asked one of my comm buddies, and gleaned a few points. The disruption of the cell signal will also reduce its field dissipation, and this is a logarithmic (exponential) effect. Given that the phone’s signal range is miles, the attenuated field could still be hundreds of feet.

The disrupted signal will also lose most of its potential for generating harmonics with the beacon signal, and this could be the most significant detail, since the phone is actually operating on several bandwidth ranges: cell, wifi, Bluetooth, etc(?).

I think the use of a Faraday bag is worth consideration, but if you do this, you might want to keep your phone in airplane mode anyway, because the loss of link drains the phone battery faster while it searches for a cell tower.

I’d probably skip the bag and just use airplane mode.

[Ørion]

I’d probably skip the bag and just use airplane mode.

My AT experience is entirely theoretical but isn't the rule of thumb that even in airplane mode phones can potentially disrupt a beacon in search mode?

You're supposed to keep the beacon 20 inch away from any electronics when searching for this reason. Fairly easy to do as long as you keep your phone in a lower pant pocket while the beacon is in your hand, but I wonder how many people use their beacon with a sport/smart watch on their wrist which has similar, if smaller, disruptive effects.

[lucknau]

My AT experience is entirely theoretical but isn't the rule of thumb that even in airplane mode phones can potentially disrupt a beacon in search mode?

You're supposed to keep the beacon 20 inch away from any electronics when searching for this reason. Fairly easy to do as long as you keep your phone in a lower pant pocket while the beacon is in your hand, but I wonder how many people use their beacon with a sport/smart watch on their wrist which has similar, if smaller, disruptive effects.

I think by this logic you would want to keep the Faraday bag 20” away from the beacon, as well. Just seems like extra clutter to me, unless maybe you’ve got a radio key fob or something with an antenna you can’t disable

[adrenalated]

Yes, phones can still cause interference in airplane mode. Keeping it away from the beacon (20cm in transmit, 50cm in search) regardless of whether or not you're in airplane mode is advised. Turning it off is even better.

[Ørion]

I think by this logic you would want to keep the Faraday bag 20” away from the beacon, as well. Just seems like extra clutter to me, unless maybe you’ve got a radio key fob or something with an antenna you can’t disable

The original idea of the OP, I think, would be that a Faraday bag would reduce the distance needed to avoid interference.

Not certain I'd trust a random bag to actually do the job nor do I have the equipment to test such a thing. Rather just keep the phone off

[lucknau]

The original idea of the OP, I think, would be that a Faraday bag would reduce the distance needed to avoid interference.

Not certain I'd trust a random bag to actually do the job nor do I have the equipment to test such a thing. Rather just keep the phone off

Ahh.

It would reduce the distance. Not sure how much. Could also constitute as an obstruction, if you think about it, given that EMF can’t pass through it easily. It would be cool to test the signal of the beacon while inside the bag. The little bit of reading I did about the bags warned about degradation of the mesh, over time.

What does cell EMF do to the beacon signal, exactly? Does it reduce the antenna range? Or like mess with the triangulation of distance? I’ve done beacon tests with my cell and my beacon in the same pocket, and the beacon was always visible to my friends beacons.

As a rule I’m downright annoyingly paranoid and careful, but I’ve always considered this guideline as either spillover from the brick phone era, or total bullshit like turning off electronics before your flight takes off. I’ve never worried about it.

[adrenalated]

Different phones and different beacons respond to each other differently. Some won't have interference problems at all.

On an older beacon and phone combo I had, having a phone on and close to the beacon would result in a ghost second signal that would flicker in and out of reception. In other words, while searching, the beacon would sometimes pick up the phone and try to point you towards that rather than towards the buried beacon.

Other friends have reported that the beacon was slower to respond and sent them in a less direct route if their phone was on versus when it was not in back-to-back practice testing.

I'm not enough of an expert to explain the physics of what's happening but I have personally seen and experienced cell phone interference with an avalanche beacon. I've also had phone beacon combos that did not display any unusual behavior. I haven't experimented with my current phone/beacon combo, mostly because I have my phone turned off 95% of the time.

[total_immortal]

Ahh.

It would reduce the distance. Not sure how much. Could also constitute as an obstruction, if you think about it, given that EMF can’t pass through it easily. It would be cool to test the signal of the beacon while inside the bag. The little bit of reading I did about the bags warned about degradation of the mesh, over time.

What does cell EMF do to the beacon signal, exactly? Does it reduce the antenna range? Or like mess with the triangulation of distance? I’ve done beacon tests with my cell and my beacon in the same pocket, and the beacon was always visible to my friends beacons.

As a rule I’m downright annoyingly paranoid and careful, but I’ve always considered this guideline as either spillover from the brick phone era, or total bullshit like turning off electronics before your flight takes off. I’ve never worried about it.

I have done pretty thorough testing with my phone and beacon (Tracker 3) and I don't have any issues while in SEND mode, but I have had problems in SEARCH mode (once in a real life search!). The interference while in SEARCH isn't consistent and I think it has to do with proximity to my phone. I have simply added turning off my phone as one of my first steps when starting a beacon search, but this just caught my eye as a potential tool to save me from that step.

[lucknau]

I have done pretty thorough testing with my phone and beacon (Tracker 3) and I don't have any issues while in SEND mode, but I have had problems in SEARCH mode (once in a real life search!). The interference while in SEARCH isn't consistent and I think it has to do with proximity to my phone. I have simply added turning off my phone as one of my first steps when starting a beacon search, but this just caught my eye as a potential tool to save me from that step.

Oh, damn. That is really good to know, thanks. I don’t remember learning that (not saying much), and had never thought of it. Should be able to test it out by wrapping a cell phone in a couple layers of tin foil.

[1000-oaks]

The interference while in SEARCH isn't consistent and I think it has to do with proximity to my phone.

I've suspected the interference pops up when the phone is periodically querying the cell tower for data updates, but it's just a guess.

[sfotex]

If you put your beacon in the cage it will be safe from interference...













Joking!!! That's a horrible idea.

[total_immortal]

I've suspected the interference pops up when the phone is periodically querying the cell tower for data updates, but it's just a guess.

That's a good theory, I have also noticed that turning on the screen with my beacon right next to it produces a ghost signal.

[ASmileyFace]

That's a good theory, I have also noticed that turning on the screen with my beacon right next to it produces a ghost signal.

I noticed this while playing with my beacons last season as well. Not sure why, but the screen being on makes a difference for sure.

[sfotex]

I noticed this while playing with my beacons last season as well. Not sure why, but the screen being on makes a difference for sure.

The screen throws out a lot of noise. You can get two beacons in search mode close to each other and observe the same thing.