# finding bugs

**URL:** <https://boards.straightdope.com/t/finding-bugs/174769>\
**Category:** Factual Questions\
**Created:** [May 12, 2003, 7:08pm UTC](https://boards.straightdope.com/t/finding-bugs/174769 "2003-05-12T19:08:48Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![susie426](https://avatars.discourse-cdn.com/v4/letter/s/41988e/32.png) [@susie426](https://boards.straightdope.com/u/susie426)\
**Post date:** [May 12, 2003, 7:08pm UTC](https://boards.straightdope.com/t/finding-bugs/174769/1 "2003-05-12T19:08:48Z")

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So…not that I’m paranoid or anything, but how does one “sweep” for electronic surveilance in a home or office? Been watching too much tv and reading too many spy/government conspiracy books…but exactly how would I find out if Big Brother is watching me and listening to my phone conversations?

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**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\
**Post date:** [May 12, 2003, 7:13pm UTC](https://boards.straightdope.com/t/finding-bugs/174769/2 "2003-05-12T19:13:54Z")

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There’s several techniques for detecting bugs and wiretaps. Wireless bugs can be detected with RF “sniffers” that pick up radio signals. Telephone taps can be detected using a device called a reflectometer. This sends a pulse down the phone line (or any other wire or cable, in fact) and displays the singal reflected back from it. Any change in the impedance of the line causes a bit of signal to be reflected back with characteristics dependant on the nature of the imedance variance.

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**Author:** ![susie426](https://avatars.discourse-cdn.com/v4/letter/s/41988e/32.png) [@susie426](https://boards.straightdope.com/u/susie426)\
**Post date:** [May 13, 2003, 1:56pm UTC](https://boards.straightdope.com/t/finding-bugs/174769/3 "2003-05-13T13:56:56Z")

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Thanks Q.E.D -I’ve always wondered about that!!

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**Author:** ![Mort\_Furd](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mort\_Furd](https://boards.straightdope.com/u/Mort_Furd)\
**Post date:** [May 13, 2003, 2:29pm UTC](https://boards.straightdope.com/t/finding-bugs/174769/4 "2003-05-13T14:29:45Z")

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Then there are active detectors that transmit a signal. Any bug contains diodes of some kind (any p-n or n-p junction will do, even in a transistor) and the wiring will pick up some of the signal. The diode will produce a harmonic of the transmitted signal and the wiring will re-broadcast it. This kind of detector will find bugs even if they are turned off. It will also detect any kind of electronic device.  
I read once that when the US built a new building for the US embassy in Moscow, the Russians had the local construction workers dump sacks full of diodes into the cement. The US then had a building that they could never be sure wasn’t bugged. I don’t know if the story is true, but it sounds good, anyway. Does anyone know the truth of this story?