Q-factor and BER results

[AMIR MURAD]

Hi friends,
I am new here, i see optisystem example Coherent 4 QAM.osd, and also see electrical modulations examples. for all these schemes i found constant value of Q-Factor,eye height=0, BER=1. also for eye diagram i only got one line instead of multiple lines to make eye.i attached BER result herewith. kindly guide me how to get plausible results please.
Thanks in advance.

[Damian Marek]

That is an older example and it really should not be set up that way. I’ll fix it.

A better example to look at would be one of the examples in the sub-folder 8 QAM, 16 QAM etc. Here a BER Test Set is used to experimentally count the bit errors. The BER Analyzer is not giving the proper BER because it is hooked up to the signal after it has been detected and regenerated, giving an “ideal” eye diagram, even though some of the bits may have been detected incorrectly.

Regards

[Lukas Koritar]

Hi Damian,
Could you to attach examples for 8QAM and 16QAM, please? Now we have Optisystem 14 but examples of modulation scheme I see from Optisystem 12 where are the old examples. I have done 4QAM but now I don’t know how to set up M-ary threshold detectors for higher QAM modulation. If it’s possible, you could send also 8-PSK. Thank you very much..
Regards

[Ranjeet Kumar]

Hi Amir sir,
Here i am attaching an osd file of coherent 4 QAM design. you can vary different parameters to see varitions in ber and q factor.

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