VALUE OF Q IN ENCRYPTED SIGNAL

[vipul]

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.

[Heitor Galvao]

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.

[Heitor Galvao]

Watch as this well explained here in this pdf

[Damian Marek]

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

[Heitor Galvao]

Yes, explains very well even

[Ravil]

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

[Author]

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