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VALUE OF Q IN ENCRYPTED SIGNAL

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(joined September 2014)
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HI EVERYBODY…
I AM WORKING ON OPTICAL SIGNAL ENCRYPTION-DECRYPTION SYSTEMS.SO WHEN I ENCRYPT THE SIGNAL I FIND VERY POOR EYE DIAGRAM WHICH IS OBVIOUS BUT SIMULTANEOUSLY I AM GETTING Q =ZERO .IS I NORMAL??
Q MEANS QUALITY FACTOR .WHAT EXACTLY QUALITY MEANS? I MEAN QUALITY OF SIGNAL IS SUBJECTIVE TERM WHICH INCLUDES MANY PARAMETERS MEANS QUALITY OF SIGNAL IN TERMS OF SIGNAL POWER/SIGNAL DISTORTION/BIT ERROR RATE ETC.
SO CAN ANYONE TELL Q VALUE DEPENDS ON EXACTLY WHICH PARAMETER OF SIGNAL.
THANK YOU.

Responses (5):

    • #15108
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      vipul
      Participant

      HI EVERYBODY…
      I AM WORKING ON OPTICAL SIGNAL ENCRYPTION-DECRYPTION SYSTEMS.SO WHEN I ENCRYPT THE SIGNAL I FIND VERY POOR EYE DIAGRAM WHICH IS OBVIOUS BUT SIMULTANEOUSLY I AM GETTING Q =ZERO .IS I NORMAL??
      Q MEANS QUALITY FACTOR .WHAT EXACTLY QUALITY MEANS? I MEAN QUALITY OF SIGNAL IS SUBJECTIVE TERM WHICH INCLUDES MANY PARAMETERS MEANS QUALITY OF SIGNAL IN TERMS OF SIGNAL POWER/SIGNAL DISTORTION/BIT ERROR RATE ETC.
      SO CAN ANYONE TELL Q VALUE DEPENDS ON EXACTLY WHICH PARAMETER OF SIGNAL.
      THANK YOU.

    • #15111
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      Heitor Galvao
      Participant

      Q factor measures the quality of an analog transmission signal in terms of
      its signal-to-noise ratio (SNR).As such, it takes into account physical impairments to the signal –
      for example, noise, chromatic dispersion and any polarization or non-linear effects – which can
      degrade the signal and ultimately cause bit errors. In other words, the higher the value of Q factor
      the better the SNR and therefore the lower the probability of bit errors.

      +2
    • #15112
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      Heitor Galvao
      Participant

      Watch as this well explained here in this pdf

      Attachments:
      • #15134
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        Damian Marek
        Participant

        The attached pdf explains the Q factor calculation for an eye diagram very well!

    • #15114
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      Ravil
      Participant

      Yes, low Q-factor, low OSNR and high BER are the main indicators of decryted signal distortion.

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