OSNR and BER relation

[gaganpreet Kaur]

Hi my query is in some of simulation results WDM analyzer between input and output before receiver detection show OSNR as high as 93 dB but even of my best efforts no acceptable BER or eye diagram is achieved . when i compare it with sample file in terms of power detected at receiver with help of electrical power meter , power is more than in the sample file . my first concern why if more power is received at output and it is possible that we don’t get BER less than 10^-9 when compared to a system which has lower output power but still BER is >10^-9.

My second question is does OSNR andBER relation deifned by
Log10 (BER) = 10.7-1.45 (OSNR) hold true for all system designed in optisystem.
Kindly help it is important.

[Damian Marek]

I’m away from the office this week, so my responses will be limited. However, I believe this stems from the WDM Analyzer being used incorrectly. Look at the WDM Component Properties and it may give you a more in depth answer but here goes my quick explanation.

The WDM Analyzer calculates the OSNR in two distinct ways in the first method it simply compares the signal power to the Noise bins power. By default noise bins have been changed to be converted to a signal. Most likely any noise in your project has been added to the signal and no noise bins are present giving you an OSNR of 93 dB, which is quite high. Verify with an Optical Spectrum Analyzer if there is any noise present and what the expected OSNR should be.

The second method uses the peak signal power and lets the user choose how far to offset the frequency to choose the noise power. In WDM systems this is normally half the channel bandwidth which corresponds to the frequency directly between channels.

[gaganpreet Kaur]

Thank you Damian for answering to my query. it is first case where noise in WDM analyzer shows -100 dB so probably whole of signal is converted to OSNR. when checked with OSA it shows noise but at different set of frequencies. what does that imply?

[gaganpreet Kaur]

most importantly how do i get correct OSNR.

[Aabid Baba]

this may help you
https://cdn.optiwave.com/wp-content/uploads/2015/10/13043537/TC-Optical-Signal-to-Noise-Ratio-OSNR.pdf?b9cd8c

[gaganpreet Kaur]

Thank you so much aabid. it helped me a lot to understand the dependence and relation between OSNR,BER and eye openings. thanks again but my question stands for dual port analyzer results. Also in my simulations using the option convert noise bins does not effect the output results.

[Aabid Baba]

you are welcome gaganpreet.
well i think you need to go through post #29752 again where Damian sir had mentioned how we can use dual port WDM analyzer for calculating parameters. As such i haven’t used it for now in my project work.
Please post your response when you are done with it. It may be helpful for me too.

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