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I'm looking for a way to shield or protect produced signal or wave. In mechanics suppose you run the wave in tunnel. Is there a way to do it in transmitting the signals or waves created by mobile phone or wifi or in the internet?

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    $\begingroup$ What are you trying to protect the signals against? $\endgroup$
    – MBaz
    Feb 13 '16 at 18:48
  • $\begingroup$ You say you don't want cryptography. Mobile phone network and Internet transmissions are handled by service providers which is out of your control, so cryptography would be the only option. So I think you are asking for too much. $\endgroup$ Feb 14 '16 at 7:27
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    $\begingroup$ Thanks @OlliNiemitalo, the question relates to the ways the signal until it reaches the networks and alternatively if there is a way to transmit it between 2 people with protection with no need to use service providers. For instance to use wifi networks that the signal will pass through. $\endgroup$
    – Avi
    Feb 14 '16 at 8:31
  • $\begingroup$ Can you use a cable or does it need to be aerial? $\endgroup$ Feb 14 '16 at 9:59
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    $\begingroup$ @Avi have you considered steganography / security through obscurity? Say you would send innocuous-looking packets and embed information in the times you send them. $\endgroup$ Feb 15 '16 at 9:35
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Signal integrity is a full area of electrical engineering and signal engineering. A few examples :

  • To protect a propagating signal in free-space you can emit it louder (=more transmitting power, hence increasing signal to noise ratio (SNR)).
  • Numerical transmissions often include error correcting codes.
  • To protect propagating signals in cables, most of them are electromagnetically shielded.

I may detail my answer according to what you want to know exactly.

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  • $\begingroup$ Thank you all. I would like to protect the signals that I transmit from my mobile phone and my wire phone and the transmitted information via internet. $\endgroup$
    – Avi
    Feb 13 '16 at 19:04
  • $\begingroup$ So you are looking for data encryption software, maybe you should ask crypto.stackexchange.com $\endgroup$
    – MaximGi
    Feb 13 '16 at 19:08
  • $\begingroup$ @Avi Allow me to insist: it's impossible to protect something if you can't describe what the threat is. Are you protecting against noise, interference, distortion, eavesdroppers, aliens, ...? $\endgroup$
    – MBaz
    Feb 13 '16 at 19:09
  • $\begingroup$ Thanks, MaximGi. I don't want to encrypt the information I would like to protect it in its origin - the signal. $\endgroup$
    – Avi
    Feb 13 '16 at 19:09
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    $\begingroup$ Well...once your signal is in the air, it can be intercepted by anyone. The only way to protect is to encrypt the information contained in it, or to use a military grade frequency shift keying modulation. $\endgroup$
    – MaximGi
    Feb 13 '16 at 19:16
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You could use an antenna array to focus the transmission to the intended receiver only and to send a more powerful jamming signal to all other directions.

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  • $\begingroup$ Thanks @OlliNiemitalo, but first I don't know the exact location of the receiver and second someone can intercept the signal that was sent to receiver. $\endgroup$
    – Avi
    Feb 14 '16 at 11:03
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If you send a signal wirelessly, your options would be: 1) avoiding that a bad guy gets the signal in the first place (antenna, beamforming, frequency hopping) 2) avoiding that a bad guy can make any sense of the signal (eg encryption)

Some schemes might blur the distinction between 1 and 2.

I have a hard time coming up with any other scheme.

Is this an academic exercise, or a practical problem?

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