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Education Blocking Mobile Phone Signals

Discussion in 'General' started by .//TuNdRa, 24 Aug 2017.

  1. .//TuNdRa

    .//TuNdRa Resident Bulldozer Guru

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    Hi all,

    I'm hoping one of you will Out-Nerd me here;

    Bit of a fun one today - I'm testing a failure case for a mobile phone where, when it loses network, it'll fail to reconnect. Problem is; I need to be able to control when and where it loses network in order to figure out exactly what it takes to cause the phone to entirely fail.

    I've tried a couple of basic things already, making up a foil lined box that happily killed all signal on my Smartphone (Xperia X) But the device just shrugged, stepped down to GSM and carried on without a care.

    Anyone have any further ideas on what I could do to completely cut this thing off from signal? I've even thrown this thing into a Microwave and it still doesn't give up on connecting.

    Any help would be appreciated.
     
  2. RedFlames

    RedFlames ...is not a Belgian football team

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    Turn Airplane mode on...
     
  3. .//TuNdRa

    .//TuNdRa Resident Bulldozer Guru

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    I appreciate the thought, but this only happens when the device is meant to be connected and loses it, I'm not trying to turn off connections, just provoke a failure I know does happen.
     
  4. BigAde2072

    BigAde2072 New Member

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  5. mrlongbeard

    mrlongbeard Well-Known Member

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    Drive out into the countryside.
     
  6. jrs77

    jrs77 Well-Known Member

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    ...
     
    Last edited: 2 Jan 2018
  7. legoman

    legoman breaker of things

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    Faraday cage?
     
  8. Guest-23315

    Guest-23315 Guest

  9. .//TuNdRa

    .//TuNdRa Resident Bulldozer Guru

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    Device is annoyingly resilient, Microwave does kill signals on my smartphone, but this thing is apparently a tougher nut to crack than my smartphone, also checked; Microwave is working normally, heating outside to surface of sun while inside is still frozen, no problem here!

    Plausible, but long iteration time, this thing falls over once in every couple of tests, definitely keeping it in mind as a fallback if all else fails.

    Now just to find somewhere to source that sort of thing for a one-off set of testing, I don't routinely need to kill signals, just enough to tell the OEM I'm not making things up when I report the issue.

    Does work! Problem is purely a practical one, I'm testing a couple of different locations and I'd rather not have to lug a minifridge or Microwave with me for it, seems that it'll only work properly if the cage is Grounded too, for a relatively dumb phone; it's very resilient.

    I have considered giving up and seeing if anyone will make me a lead Box.
     
  10. wolfticket

    wolfticket Downwind from the bloodhounds

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    Windowed faraday bags are apparently a thing you can buy.
     
  11. teacherboy

    teacherboy Part Carbon/Nylon/Bovine

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    Wrap in tin foil and drop into a metal filiing cabinet?
     
  12. Ramble

    Ramble Ginger Nut

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    Faraday cages are surprisingly difficult to build, it's still the number 1 foolproof way of doing it though. Make sure you wrap with multiple layers (and seal very well, RF can leak in through tiny holes) and earth the foil - it will not work correctly if it is not earthed, attach it to some plumbing or something.
     
  13. Stotherd-001

    Stotherd-001 Member

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    I would open it up and break its antenna lines. Alternatively a local university might have a signal blocked room available? If they have any electrical research labs they'll probably have one.
     
  14. boiled_elephant

    boiled_elephant Whitelist Bit-Tech in your adblock!

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    Ditto any old military structures build in the war era. Anything with 3 floors or more; they tend to have double-brick reinforced walls, metal in the structure, lots of concrete. I work in one and my phones are all 0 bars inside on the ground floor.
     
  15. Dr. Coin

    Dr. Coin Active Member

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    This is the most critical step that is most often missed. Also foil all sides, floor, ceiling, and walls. Conductive foil tape should help with the construction.

    Do you need to be able to operate the phone while it is without signal?
     
  16. gagaga

    gagaga Member

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    If it's testing when the phone thinks it's got connection, but not really, then use wifi - attach it to an access point then pull out the internet uplink cable from the back. The phone will still have a strong wifi connection but no internet. Our app developers took an age to deal with that setup (happens in conference centres with lots of WAPs but poor uplink).
     
  17. Corky42

    Corky42 Where's walle?

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    Wouldn't sticking it in one of those EM bags that come with things like GPU's, MoBo's and other similar phone sized sensitive electronics.
     
  18. MiNiMaL_FuSS

    MiNiMaL_FuSS ƬӇЄƦЄ ƁЄ ƇƠƜƧ ӇЄƦЄ.

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    Come to my place (Norfolk), none of that signal nonsense here boyo.
     

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