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Link Posted: 7/16/2019 8:20:45 AM EDT
[Last Edit: 7/16/2019 8:22:18 AM EDT by The_Beer_Slayer]
Link Posted: 7/17/2019 12:28:14 AM EDT
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Originally Posted By Gyprat:

My Samsung S5 has a removable battery. The phone is almost brand new. I bought it only 4 years ago and it does everything just fine. I don't plan to replace this phone anytime soon.
I really love the power saving feature. The power saving mode switches off all non-essential apps and features. The screen goes black and white and the battery will last at least a week without recharging (with moderate use). Charging ports went to crap on all of my previous phones. This phone takes a much wider plug and it's hard to damage.
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4 years old and almost new phone does not compute. You realize they’ve moved on to the 10 now right?
Link Posted: 7/19/2019 1:28:52 AM EDT
[Last Edit: 7/19/2019 1:35:46 AM EDT by jonathan2421]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By The_Beer_Slayer:
your phone can not only be tracked while off, the camera and mic can also be activated and monitored remotely while "off". i know for a fact federal and state law enforcement have access to those tools. i am sure bad guys with malware do as well. That said it requires a LOT of paperwork to get such things approved for use. it's not something the gov is going to do unless they are looking at you already. if the battery is in and charged it is never truly "off".

power it off and let it sit for a few days. you will notice the battery has dropped a minor amount while powered off.
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Yes, but if it's not communicating with cell towers there is no communicating with the phone, as you don't know where it is. And we know that except in circumstances where phones have been compromised with software to remain online when turned off, phones do not stay connected to towers while off.

It's certainly possible to listen passively for a signal sent to the phone somehow, but that would require being near the phone. It would also kill the battery pretty quick even when turned off.

ETA: I'm certain that there are all kinds of ways to compromise phones, but I think most of the stuff posted in this thread is little more than hearsay.
Link Posted: 7/19/2019 8:59:04 AM EDT
Something I just thought of: instead of pulling the battery, what would happen if you pulled the SIM card? Would that be enough to keep the cell phone from being tracked?
Link Posted: 7/19/2019 9:13:26 AM EDT
Link Posted: 7/19/2019 9:28:28 AM EDT
There's a reason they make the battery non removable on most phones.
Link Posted: 7/19/2019 10:28:44 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By JohnAdamsIII:
There's a reason they make the battery non removable on most phones.
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There sure is! They are all going water proof. When I bought my S6 active it was the only model in the S6 line that was water proof, and the only one without a removable battery. Now they are all water proof.

Apple sealed up the phone for the same reason they solder the memory onto their laptop motherboards now, because they are dicks who want you to buy a new device sooner.
Link Posted: 7/19/2019 11:03:33 AM EDT
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Originally Posted By intheburbs:
The "off" button works pretty well for me. No bag required.

Unless you're the tinfoil hat-type that believes your phone can still be tracked and is never truly off.
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Don't forget to remove the battery. It's never really off.
Link Posted: 7/19/2019 11:50:54 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jonathan2421:
There sure is! They are all going water proof. When I bought my S6 active it was the only model in the S6 line that was water proof, and the only one without a removable battery. Now they are all water proof.

Apple sealed up the phone for the same reason they solder the memory onto their laptop motherboards now, because they are dicks who want you to buy a new device sooner.
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Originally Posted By jonathan2421:
Originally Posted By JohnAdamsIII:
There's a reason they make the battery non removable on most phones.
There sure is! They are all going water proof. When I bought my S6 active it was the only model in the S6 line that was water proof, and the only one without a removable battery. Now they are all water proof.

Apple sealed up the phone for the same reason they solder the memory onto their laptop motherboards now, because they are dicks who want you to buy a new device sooner.
Or maybe Apple did it to make their phones waterproof too.
Link Posted: 7/19/2019 1:43:03 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By JohnAdamsIII:
There's a reason they make the battery non removable on most phones.
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and, what is the reason?

do you work for apple or samsung?
Link Posted: 7/20/2019 4:01:56 PM EDT
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Originally Posted By Josh:

Or maybe Apple did it to make their phones waterproof too.
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Well eventually, they did. There were many generations of iPhone without a removable battery that were definitely not water proof.
Link Posted: 7/21/2019 10:04:27 AM EDT
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Originally Posted By Josh:
I’m curious which part of “low power mode” you believe GPS and location reports over cellular data count as.
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Originally Posted By Josh:
Originally Posted By planemaker:
Originally Posted By draver:
Originally Posted By 96Ag:

Of course you would say that.

Except that no one has been able to explain how these devices are powered for tracking when they are off. The battery self discharge accounts for any battery drain over time, just like all devices using Li-ion battery tech. Flashlights, PVS-14's, drones, digital cameras, stored rechargables, etc. all experience battery drop over time. As I've stated, my ipads lose about 1-2% every few WEEKS when off. For a cellular device to reach out to a tower or black van, it needs power. Please tell us where it's getting it, because it does not seem to be from the internal battery.
Because they are not actually "off" switches, they are a logic switch to turn the device to an exceptionally low power usage mode. To actually turn it off, you'd have to remove the battery. I can't in my cell phone without destroying the phone, something that pi$$ses me off greatly. Note that carriers can and often do download software to your phone without your knowledge, primarily to maintain the security and availability of their network.

So, yes, you can track a phone while "off" because it's not really off. As for whether you can track a phone without a battery, that is much, much more difficult and you'd have to know a lot about that particular phone for the methods I've heard about to be effective. Battery out, in a Faraday bag, most likely not trackable. Not usable, mind you, but not trackable either.
I’m curious which part of “low power mode” you believe GPS and location reports over cellular data count as.
Don't need GPS in the phone if the unit is talking to the cell towers. Location can be derived from them.
Link Posted: 7/28/2019 1:25:11 PM EDT
Link Posted: 7/28/2019 1:29:32 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Taft:
Uh.....

How about a metal GI ammo can ?

Seems like that would work.
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As long as the closure gasket is effective from an RF POV, at the frequency of interest.
Link Posted: 7/28/2019 1:53:19 PM EDT
Link Posted: 7/28/2019 3:34:30 PM EDT
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Originally Posted By planemaker:
Don't need GPS in the phone if the unit is talking to the cell towers. Location can be derived from them.
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Originally Posted By planemaker:
Originally Posted By Josh:
Originally Posted By planemaker:
Originally Posted By draver:
Originally Posted By 96Ag:

Of course you would say that.

Except that no one has been able to explain how these devices are powered for tracking when they are off. The battery self discharge accounts for any battery drain over time, just like all devices using Li-ion battery tech. Flashlights, PVS-14's, drones, digital cameras, stored rechargables, etc. all experience battery drop over time. As I've stated, my ipads lose about 1-2% every few WEEKS when off. For a cellular device to reach out to a tower or black van, it needs power. Please tell us where it's getting it, because it does not seem to be from the internal battery.
Because they are not actually "off" switches, they are a logic switch to turn the device to an exceptionally low power usage mode. To actually turn it off, you'd have to remove the battery. I can't in my cell phone without destroying the phone, something that pi$$ses me off greatly. Note that carriers can and often do download software to your phone without your knowledge, primarily to maintain the security and availability of their network.

So, yes, you can track a phone while "off" because it's not really off. As for whether you can track a phone without a battery, that is much, much more difficult and you'd have to know a lot about that particular phone for the methods I've heard about to be effective. Battery out, in a Faraday bag, most likely not trackable. Not usable, mind you, but not trackable either.
I’m curious which part of “low power mode” you believe GPS and location reports over cellular data count as.
Don't need GPS in the phone if the unit is talking to the cell towers. Location can be derived from them.
Cellular radios use more power than GPS receivers.

You didn't answer the question.
Link Posted: 7/29/2019 2:08:39 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Taft:
Uh.....

How about a metal GI ammo can ?

Seems like that would work.
View Quote
The ammo cans use rubber gaskets (or whatever rubbery material they use). There will be an " RF transparent" gap between the can and the lid. This is enough to act as a slot antenna thus significantly reducing shield attenuation.

A cheap way to improve it: Use sandpaper and remove the paint from the can's opening edges (that sit against the gasket when the can is closed). Apply a thin layer of NoOx paste on bare metal of the the sanded edges. Bearing grease can be used if nothing else is available.
Cut a piece of uncoated aluminum foil, slightly larger than the can opening. Place the foil over the can opening and close the lid on top of it. Put the shiny side against the edges if the aluminum foil is coated on one side.
This should provide a much better shielding. You can also put some 2" aluminum HVAC sticky tape around the closed lid gap to further improve the shielding.
Link Posted: 7/29/2019 2:46:14 PM EDT
New to this site. Any phone is not allowed in a High Side discussion. Does not matter if it is on or off. That is Uncle Sams direction. I never take my phone with me to places I don’t want people listening to me.
Link Posted: 7/29/2019 4:09:01 PM EDT
[Last Edit: 7/29/2019 4:09:24 PM EDT by EXPY37]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Wazy:
New to this site. Any phone is not allowed in a High Side discussion. Does not matter if it is on or off. That is Uncle Sams direction. I never take my phone with me to places I don’t want people listening to me.
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Precisely!

Even if the [obvious] battery is removed.
Link Posted: 7/29/2019 9:23:11 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Josh:
Cellular radios use more power than GPS receivers.

You didn't answer the question.
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Originally Posted By Josh:
Originally Posted By planemaker:
Originally Posted By Josh:
Originally Posted By planemaker:
Originally Posted By draver:
Originally Posted By 96Ag:

Of course you would say that.

Except that no one has been able to explain how these devices are powered for tracking when they are off. The battery self discharge accounts for any battery drain over time, just like all devices using Li-ion battery tech. Flashlights, PVS-14's, drones, digital cameras, stored rechargables, etc. all experience battery drop over time. As I've stated, my ipads lose about 1-2% every few WEEKS when off. For a cellular device to reach out to a tower or black van, it needs power. Please tell us where it's getting it, because it does not seem to be from the internal battery.
Because they are not actually "off" switches, they are a logic switch to turn the device to an exceptionally low power usage mode. To actually turn it off, you'd have to remove the battery. I can't in my cell phone without destroying the phone, something that pi$$ses me off greatly. Note that carriers can and often do download software to your phone without your knowledge, primarily to maintain the security and availability of their network.

So, yes, you can track a phone while "off" because it's not really off. As for whether you can track a phone without a battery, that is much, much more difficult and you'd have to know a lot about that particular phone for the methods I've heard about to be effective. Battery out, in a Faraday bag, most likely not trackable. Not usable, mind you, but not trackable either.
I’m curious which part of “low power mode” you believe GPS and location reports over cellular data count as.
Don't need GPS in the phone if the unit is talking to the cell towers. Location can be derived from them.
Cellular radios use more power than GPS receivers.

You didn't answer the question.
And? Low power mode doesn't mean off. Any number of methods could be used to intermittently ping towers from which location can be derived directly. Using periodic control-only handshakes on an infrequent basis can be used to discern location. You do understand that even when the fone is "on" that it modulates the power level it uses to talk to cell towers, don't you? Why would you not think that "off" merely means using less power?

Link Posted: 7/29/2019 9:43:47 PM EDT
[Last Edit: 7/29/2019 9:44:28 PM EDT by Josh]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By planemaker:

And? Low power mode doesn't mean off. Any number of methods could be used to intermittently ping towers from which location can be derived directly. Using periodic control-only handshakes on an infrequent basis can be used to discern location. You do understand that even when the fone is "on" that it modulates the power level it uses to talk to cell towers, don't you? Why would you not think that "off" merely means using less power?

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I'm pretty sure you don't have the foggiest idea what you're talking about. You still haven't answered my question.
Link Posted: 7/30/2019 5:12:34 PM EDT
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Originally Posted By cms81586:

4 years old and almost new phone does not compute. You realize they’ve moved on to the 10 now right?
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The phone "computes" just fine. It makes and receives phone calls just fine. I can send text messages, access internet and even use the phone as a hot spot. Why the heck would I trade a perfectly good phone with a removable battery, for a new expensive gismo that has no removable battery and costs $800????
They moved to 10 now? Cool. I'll get a 10 when they move to 25...…….or maybe not. I wouldn't mind getting a flip phone with a decent prepaid plan. Unfortunately all prepaid plans really suck here in the US.
Link Posted: 7/30/2019 9:50:48 PM EDT
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Originally Posted By Josh:
I'm pretty sure you don't have the foggiest idea what you're talking about. You still haven't answered my question.
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Originally Posted By Josh:
Originally Posted By planemaker:

And? Low power mode doesn't mean off. Any number of methods could be used to intermittently ping towers from which location can be derived directly. Using periodic control-only handshakes on an infrequent basis can be used to discern location. You do understand that even when the fone is "on" that it modulates the power level it uses to talk to cell towers, don't you? Why would you not think that "off" merely means using less power?

I'm pretty sure you don't have the foggiest idea what you're talking about. You still haven't answered my question.
Actually, I do know a thing or two about a thing or two. What I am actually a little foggy on since I've been working 12-16 hours days for the last 3 weeks is what your question was exactly. I apologize for that. My memory isn't as sharp as it once was and even less so when I'm physically exhausted by the time I get home. I think I'm getting too old to work long hours.
Link Posted: 7/31/2019 8:32:40 AM EDT
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Originally Posted By ar-jedi:
and, what is the reason?

do you work for apple or samsung?
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Originally Posted By ar-jedi:
Originally Posted By JohnAdamsIII:
There's a reason they make the battery non removable on most phones.
and, what is the reason?

do you work for apple or samsung?
I would say that the number one reason is that its cheaper to have a non-removable battery than to build in a battery cradle, way to easily remove the back of the phone, etc.
Link Posted: 7/31/2019 8:58:55 AM EDT
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Originally Posted By ban-hater:
Would a potato chip bag work, saw it on a movie once. I know Arfcommers got chip bags somewhere.
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I was playing around at work one day and tried that. I was able to get a call to my phone. So I'm not sure if a chip bag works. Didn't for me
Link Posted: 7/31/2019 9:47:39 AM EDT
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Originally Posted By 55sixer:
You can get a small microwave for $35

Won’t fit in your pocket, but solid faraday cage
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Nope. Just tried that here at work. Phone rang when called.
Link Posted: 7/31/2019 9:10:27 PM EDT
[Last Edit: 7/31/2019 9:15:25 PM EDT by ar-jedi]
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Originally Posted By dreiwhit:
I would say that the number one reason is that its cheaper to have a non-removable battery than to build in a battery cradle, way to easily remove the back of the phone, etc.
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@dreiwhit
nope. go again.
Link Posted: 7/31/2019 9:14:47 PM EDT
[Last Edit: 7/31/2019 9:42:07 PM EDT by ar-jedi]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By aod886:
I was playing around at work one day and tried that (cell phone inside an aluminized bag). I was able to get a call to my phone. So I'm not sure if a chip bag works. Didn't for me.
(merged quotes)
Nope. Just tried that (cell phone inside a microwave) here at work. Phone rang when called.
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Originally Posted By aod886:
I was playing around at work one day and tried that (cell phone inside an aluminized bag). I was able to get a call to my phone. So I'm not sure if a chip bag works. Didn't for me.
(merged quotes)
Nope. Just tried that (cell phone inside a microwave) here at work. Phone rang when called.
this is EXACTLY why i wrote earlier in the thread:

Originally Posted By ar-jedi:
the particular Cheetos bag you have may provide just enough attenuation AT THE YOUR PHONE'S OPERATING FREQUENCY to decrease the currently available signal below the receiver's signal to noise threshold. THIS DOES NOT MEAN YOUR PHONE WILL NOT WORK IF YOU ARE CLOSER TO A CELL TOWER or if you walk outside and take the building attenuation out of the equation or if you are in an environment with less RF noise such as a park. IT ALSO DOES NOT MEAN THAT FREQUENCIES HIGHER OR LOWER THAN WHAT YOUR CELLPHONE IS CURRENTLY OPERATING AT ARE NOT PENETRATING THE BAG.
next, someone will be along to tell us (yet again) that an ammo can works, because it's made of metal.
Link Posted: 7/31/2019 9:41:37 PM EDT
[Last Edit: 7/31/2019 9:46:03 PM EDT by ar-jedi]
i am an engineer at an R&D facility which has on the order of 50 screened rooms and anechoic chambers -- they are used for a variety of purposes, including providing isolation of mobile terminals from the public cellular network, and "other".

the difficulty you face with realizing a shielded enclosure is neither engineering nor construction. the issues you will have surround apertures and long term reliability.

apertures are windows, doors, vents, registers, cableways, and so on. these leak RF to one extent or the other. it can be extraordinarily difficult to provide effecting shielding when there are windows, doors, vents, registers, cableways, and so on -- you know, the sorts of features that make the room liveable for people, and at a smaller scale a box usable.

long term reliability is a factor because whenever dissimilar metals are in contact in an environment containing water vapor (e.g. air), galvanic corrosion occurs. the corrosion increases the resistance between adjacent/adjoining pieces of metal, thereby decreasing shielding effectiveness.

the above are the two main problems associated with high performance shielded enclosure. it's also why it's easy to end up spending US$100K to implement a simple shielded room.

the building i work in has around 50 shielded rooms and labs, each typically about 20' x 30'. and when i say "shielded" i mean an industrial 6 sided solid wall room with >100dB attenuation of frequencies from DC to daylight. all AC power into the rooms goes through instrument-grade three phase EMC/EMI filters including LISN's. the typical door into one of these rooms is about 4 feet wide and 7 feet tall, with a raised sill and metallic finger gasketing around the entire perimeter. the metallic gasketing must be periodically cleaned in order to maintain contact conductivity, and periodically replaced to maintain contact pressure. this is the level of design and maintenance attention required to maintain 100db shielding effectiveness.

the anechoic rooms (example below) are a whole other matter. basically, an anechoic room is a shielded room into which one builds carbon absorber arrays which prevent signals INSIDE the chamber from reflecting from the floor, walls, or ceiling. the largest we have is a 10m (~33') NIST-certifed anechoic room, used for both radiated compliance and electromagnetic immunity testing. the floor is completely tiled with carbon absorber material, and the walls have carbon-impregnated trapezoidal absorbers (the white you see in the picture is from the removable foam protectors which prevent damage to the tip of the carbon absorbers, and they also make the room a hell of a lot brighter...)

ar-jedi



Link Posted: 8/1/2019 2:21:25 PM EDT
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Originally Posted By planemaker:

And? Low power mode doesn't mean off. Any number of methods could be used to intermittently ping towers from which location can be derived directly. Using periodic control-only handshakes on an infrequent basis can be used to discern location. You do understand that even when the fone is "on" that it modulates the power level it uses to talk to cell towers, don't you? Why would you not think that "off" merely means using less power?

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Sure, this is *possible*. But there is no evidence that every phone does this while powered off.

Just to make sure I am understanding you all correctly - You are suggesting that every cell phone is designed to stay in a "spy mode" when powered off, and every cell phone chip/firmware/OS manufacturer is in on this secret? And this is either kept a secret or has gone unnoticed by the hundreds of thousands (or millions?) of techs working on the technology and has also not been observed by anybody?

I know there are dev versions of phone firmware that allow you to do things like change your IMEI or one of any other completely arbitrary things. I'm not arguing that any of these things are not possible, it just seems that it requires modifying or compromising a phone.

Banning phones in a secure area doesn't imply all phones are always listening to you, just that it *is* possible and no risks are taken.
Link Posted: 8/1/2019 5:44:05 PM EDT
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Originally Posted By jonathan2421:

Banning phones in a secure area doesn't imply all phones are always listening to you, just that it *is* possible and no risks are taken.
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Good post and to add to this comment above....the bigger issue with cell phones in a SCIF is a phone can record video and audio and can also take pictures.....Both of which are not allowed inside a SCIF. It could even be someone who doesn't mean anything bad but accidentally capture classified information. Think of the Navy guy who took pictures inside a nuclear submarine. Yes you are prohibited from doing that too.

Feel free to keep your cell phone inside an ammo can or your cheetos bag if it helps you sleep at night. The only surefire method of avoiding being tracked if thats what you are scared of is to not have a phone.
Link Posted: 8/1/2019 9:06:07 PM EDT
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Originally Posted By ar-jedi:
i am an engineer at an R&D facility which has on the order of 50 screened rooms and anechoic chambers -- they are used for a variety of purposes, including providing isolation of mobile terminals from the public cellular network, and "other".

the difficulty you face with realizing a shielded enclosure is neither engineering nor construction. the issues you will have surround apertures and long term reliability.

apertures are windows, doors, vents, registers, cableways, and so on. these leak RF to one extent or the other. it can be extraordinarily difficult to provide effecting shielding when there are windows, doors, vents, registers, cableways, and so on -- you know, the sorts of features that make the room liveable for people, and at a smaller scale a box usable.

long term reliability is a factor because whenever dissimilar metals are in contact in an environment containing water vapor (e.g. air), galvanic corrosion occurs. the corrosion increases the resistance between adjacent/adjoining pieces of metal, thereby decreasing shielding effectiveness.

the above are the two main problems associated with high performance shielded enclosure. it's also why it's easy to end up spending US$100K to implement a simple shielded room.

the building i work in has around 50 shielded rooms and labs, each typically about 20' x 30'. and when i say "shielded" i mean an industrial 6 sided solid wall room with >100dB attenuation of frequencies from DC to daylight. all AC power into the rooms goes through instrument-grade three phase EMC/EMI filters including LISN's. the typical door into one of these rooms is about 4 feet wide and 7 feet tall, with a raised sill and metallic finger gasketing around the entire perimeter. the metallic gasketing must be periodically cleaned in order to maintain contact conductivity, and periodically replaced to maintain contact pressure. this is the level of design and maintenance attention required to maintain 100db shielding effectiveness.

the anechoic rooms (example below) are a whole other matter. basically, an anechoic room is a shielded room into which one builds carbon absorber arrays which prevent signals INSIDE the chamber from reflecting from the floor, walls, or ceiling. the largest we have is a 10m (~33') NIST-certifed anechoic room, used for both radiated compliance and electromagnetic immunity testing. the floor is completely tiled with carbon absorber material, and the walls have carbon-impregnated trapezoidal absorbers (the white you see in the picture is from the removable foam protectors which prevent damage to the tip of the carbon absorbers, and they also make the room a hell of a lot brighter...)

ar-jedi

https://ziva.losdos.dyndns.org/public/ham/reference/emc-chamber-inside.jpg

https://ziva.losdos.dyndns.org/public/ham/reference/emc-chamber-door.jpg
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@ar-jedi

I enjoyed your post very much. I have designed these in my mind, but have never actually seen any. Very COOL!
Funny, I thought you were a financial guy because your posts on those matters are always dead on. Turns out you are an engineer like me. I guess we can not help trying to figure out how all of the world works on a daily basis.
Thanks for the contribution!
Link Posted: 8/2/2019 2:35:43 PM EDT
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Originally Posted By MTBGunner:
I enjoyed your post very much. I have designed these in my mind, but have never actually seen any. Very COOL!
Funny, I thought you were a financial guy because your posts on those matters are always dead on. Turns out you are an engineer like me. I guess we can not help trying to figure out how all of the world works on a daily basis. Thanks for the contribution!
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@MTBGunner
one of the more interesting aspects (to me) of the anechoic room setup is the complete lack of metal above the ground plane. any metal located in the RF field can cause reflections and/or other anomalies in the chamber. for example, in the far corners of the chamber pictured above you will note two "stands" -- these are fiberglass masts which mount the antennas used to illuminate (RF-wise) the EUT (equipment under test) during immunity testing, or receive RF during emissions compliance testing. during testing, the height of the antennas must be varied, and the polarization of the antennas must be changed (vertical to horizontal). all of this is done entirely without metal -- instead, there are pneumatic cylinders made from nylon (and similar plastics) driven by air pressure carried over plastic tubing from compressors/tanks external to the chamber.

even the field strength characterization instrumentation utilized is optimized for minimal disruption of the uniformity of the RF field -- the wideband receivers are rechargable-battery-powered and housed in (wait for it...) pack-of-cigarette-sized faraday cages; the measurement signals are transmitted outside the chamber over RF-transparent fiber optics, where other instruments (spectrum analyzers) measure/record the field strength. in effect, it's as if you took the entire RF front end from a typical desktop spectrum analyzer and "remoted" it via fiber.

aside, the use of an shielded room is the primary reason why when you see DIY "EMP immunity" testing on youtube the results will differ dramatically depending on what size the room is, what frequency is being tested, how high the EUT is mounted off the floor, how big the EUT is compared to the room, and so on and so on. the reason for this is all the standing waves and reflections inside a shielded room; in fact at many frequencies the shielded room will be cavity-resonant. hence the primary purpose of an anechoic room, a completely homogeneous field environment -- from the EUT's perspective, it looks like an OATS but doesn't suffer from OATS problems.
https://interferencetechnology.com/emissions-test-facility-oats-vs-sac/
Link Posted: 8/2/2019 2:46:16 PM EDT
How about a foil lined, insulated lunch bag?
Link Posted: 8/2/2019 2:47:11 PM EDT
[Last Edit: 8/2/2019 2:52:40 PM EDT by Desert_AIP]
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Originally Posted By MarsRising:
ABC news drove around with a cell phone "off" and it was still tracked.

"Sources and methods" issues guarantee that the fact it can be tracked will be met with "tin foil conspiracy" allegations in any such thread.
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They didn't turn off data, gps and location services before turning the phone "off".
Link Posted: 8/3/2019 5:23:19 AM EDT
[Last Edit: 8/3/2019 5:24:28 AM EDT by CoyoteGray]
I have come across a problem along these lines..

I have a 12x20 portable building in my back yard I am finishing out to use as a shop.
The walls and roof have a layer of radiant heat barrier foil on the inside.
It works quite well. After I completed the AC wiring, insulation and pine tongue & grove paneling I installed a mini split.
At that point I noticed that my Wi-Fi signal from the house was limited and so was the cellular signal. Outside of the door of the shop both are great.
The windows are cheap but should work fine but I found some bubble pack type radiant barrier at Home Depot that I cut and placed into the windows to help with the sun..
Right now its crazy hot here.. At this point my Wi-Fi and cellular signal totally died. If your building a house I think using some type of radiant barrier is a great idea but you may need to install a cell signal booster.. Il be running a cable to an additional access point in the shop for Wi-Fi...
Link Posted: 8/3/2019 6:31:17 AM EDT
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Originally Posted By GoldenMead:
Lots of GD being brought into this forum again. Not sure why people dont just answer the question. Leave all the negativity out of here.

To the question. Just google faraday cell phone cases. You will see many that you can buy.

I’d also look into a wallet that stops rf so people can’t steal your credit card info.
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I prefer the old fashioned method for that... a credit card that doesn't use RF.
Link Posted: 8/3/2019 8:39:30 AM EDT
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Originally Posted By jonathan2421:

Sure, this is *possible*. But there is no evidence that every phone does this while powered off.

Just to make sure I am understanding you all correctly - You are suggesting that every cell phone is designed to stay in a "spy mode" when powered off, and every cell phone chip/firmware/OS manufacturer is in on this secret? And this is either kept a secret or has gone unnoticed by the hundreds of thousands (or millions?) of techs working on the technology and has also not been observed by anybody?

I know there are dev versions of phone firmware that allow you to do things like change your IMEI or one of any other completely arbitrary things. I'm not arguing that any of these things are not possible, it just seems that it requires modifying or compromising a phone.

Banning phones in a secure area doesn't imply all phones are always listening to you, just that it *is* possible and no risks are taken.
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Good post that demonstrates how unlikely it is that all this "Secret Squirrel" bullshit is just that. Puts the Never Off belief in the same unlikely category as "We Never Went To The Moon" because people could never keep that big of a secret for any length of time. Besides, if you put another sim in your phone, how does Black Ops know it's your phone anymore?
Link Posted: 8/3/2019 1:57:44 PM EDT
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Originally Posted By ar-jedi:
@MTBGunner
one of the more interesting aspects (to me) of the anechoic room setup is the complete lack of metal above the ground plane. any metal located in the RF field can cause reflections and/or other anomalies in the chamber. for example, in the far corners of the chamber pictured above you will note two "stands" -- these are fiberglass masts which mount the antennas used to illuminate (RF-wise) the EUT (equipment under test) during immunity testing, or receive RF during emissions compliance testing. during testing, the height of the antennas must be varied, and the polarization of the antennas must be changed (vertical to horizontal). all of this is done entirely without metal -- instead, there are pneumatic cylinders made from nylon (and similar plastics) driven by air pressure carried over plastic tubing from compressors/tanks external to the chamber.

even the field strength characterization instrumentation utilized is optimized for minimal disruption of the uniformity of the RF field -- the wideband receivers are rechargable-battery-powered and housed in (wait for it...) pack-of-cigarette-sized faraday cages; the measurement signals are transmitted outside the chamber over RF-transparent fiber optics, where other instruments (spectrum analyzers) measure/record the field strength. in effect, it's as if you took the entire RF front end from a typical desktop spectrum analyzer and "remoted" it via fiber.

aside, the use of an shielded room is the primary reason why when you see DIY "EMP immunity" testing on youtube the results will differ dramatically depending on what size the room is, what frequency is being tested, how high the EUT is mounted off the floor, how big the EUT is compared to the room, and so on and so on. the reason for this is all the standing waves and reflections inside a shielded room; in fact at many frequencies the shielded room will be cavity-resonant. hence the primary purpose of an anechoic room, a completely homogeneous field environment -- from the EUT's perspective, it looks like an OATS but doesn't suffer from OATS problems.
https://interferencetechnology.com/emissions-test-facility-oats-vs-sac/
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Originally Posted By ar-jedi:
Originally Posted By MTBGunner:
I enjoyed your post very much. I have designed these in my mind, but have never actually seen any. Very COOL!
Funny, I thought you were a financial guy because your posts on those matters are always dead on. Turns out you are an engineer like me. I guess we can not help trying to figure out how all of the world works on a daily basis. Thanks for the contribution!
@MTBGunner
one of the more interesting aspects (to me) of the anechoic room setup is the complete lack of metal above the ground plane. any metal located in the RF field can cause reflections and/or other anomalies in the chamber. for example, in the far corners of the chamber pictured above you will note two "stands" -- these are fiberglass masts which mount the antennas used to illuminate (RF-wise) the EUT (equipment under test) during immunity testing, or receive RF during emissions compliance testing. during testing, the height of the antennas must be varied, and the polarization of the antennas must be changed (vertical to horizontal). all of this is done entirely without metal -- instead, there are pneumatic cylinders made from nylon (and similar plastics) driven by air pressure carried over plastic tubing from compressors/tanks external to the chamber.

even the field strength characterization instrumentation utilized is optimized for minimal disruption of the uniformity of the RF field -- the wideband receivers are rechargable-battery-powered and housed in (wait for it...) pack-of-cigarette-sized faraday cages; the measurement signals are transmitted outside the chamber over RF-transparent fiber optics, where other instruments (spectrum analyzers) measure/record the field strength. in effect, it's as if you took the entire RF front end from a typical desktop spectrum analyzer and "remoted" it via fiber.

aside, the use of an shielded room is the primary reason why when you see DIY "EMP immunity" testing on youtube the results will differ dramatically depending on what size the room is, what frequency is being tested, how high the EUT is mounted off the floor, how big the EUT is compared to the room, and so on and so on. the reason for this is all the standing waves and reflections inside a shielded room; in fact at many frequencies the shielded room will be cavity-resonant. hence the primary purpose of an anechoic room, a completely homogeneous field environment -- from the EUT's perspective, it looks like an OATS but doesn't suffer from OATS problems.
https://interferencetechnology.com/emissions-test-facility-oats-vs-sac/
Wow! Amazing.

Do you have to pull the lights up into the ceiling and run the tests in the dark?
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