- This topic has 8 replies, 4 voices, and was last updated 9 years ago by
alistu.
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November 12, 2015 at 12:36 pm #27687
SashaParticipantHi all,
I am trying to connect the optical fiber between QAM modulator and demodulator. Can anyone please help me out, what components should I use to connect optical fiber between them?
I tried to implement the QAM sample file given in optiwave tutorial.
At the transmitter side, the constellation diagram is good as shown in the tutorial. I tried connecting the constellation diagram in the receiver side. I will attach the output screenshot. Please help me out whether it is right or not.
Thanks in advance.
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November 12, 2015 at 1:35 pm #27690
alistuParticipantHi Sasha,
Can you please upload your implementation osd file if it is possible? Thank you.
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November 12, 2015 at 2:30 pm #27691SashaParticipant
Hi Alitsu,
I am working in Optisystem version4 and it is available in my school. You can find the file QAM – Transmitter and Receiver.osd in samples library. I will upload the file when I am in school.
Thanks in advance.
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November 16, 2015 at 1:54 pm #27798SashaParticipant
Hello all,
I attached a file here. Please take a look at it.
Thanks in advance.
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November 16, 2015 at 2:09 pm #27804SashaParticipant
Hello all,
I implemented the Coherent Optical Transmission Optical System given in optiwave tutorial.
I got the different constellation diagram at the receiver.
Can anyone please help me out.
Thanks in advance.
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November 17, 2015 at 4:13 am #27817
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ParticipantThere is always some issue if you simulate system designed in older version in a newer version. So what you can do is install the newer version and try it. If the problem still exists please do share.
Regards.
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November 17, 2015 at 8:33 am #27825alistuParticipant
Hi Sasha,
I checked it by comparing it to the OptiSystem sample coherent 4-QAM and I must say I got really different constellations by the changes I applied to the implementations. By changing M-ary pulse generators bias and gain (gain=-2, bias=2) which were the main problem I think, I managed to get the constellation you can see. It was the best I could achieve although I tried make changes exactly according to the QAM sample. Here I have used coherent receiver component, even though yours was all right.
Regards
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November 18, 2015 at 12:59 am #27849
Dr. Dhiman KakatiParticipantHi Alistu,
I have seen in many cases that the constellation points gets elongated in a circular fashion as that you have attached in the comment above #27825, So can you tell me the reason for waht it happens so ??in some another cases I have seen that if we do not connect the fiber the constellation comes quite good and clear points at the receiver side but when we add a fiber (Standard single mode fiber) the constellation points are shifted (not elongated) in anticlockwise direction. What may be the cause for this? Please anyone make me clear.
I need to mention that I don’t want to use DSP in this case as using DSP we can correct this. I don’t have the design file with me now, If anyone has faced the same problem as me please answer here.
With regards,
Dhiman-
November 18, 2015 at 11:35 am #27877alistuParticipant
Hi Dhiman,
I really don’t know the problem with the above simulation, as I tried to change it according to the sample file but did not manage to get the proper result. As for the rotation, you can refer to the below topic which I had started a while ago to read a whole discussion:
Regards
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