- This topic has 4 replies, 2 voices, and was last updated 9 years, 8 months ago by
xiaoyong chen.
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December 10, 2014 at 7:56 am #16585
xiaoyong chen
ParticipantHello everyone,
I have a problem in design of a Niquist-filtered 100 Gbps PM-DQPSK transmitter. I tried to use the optical raised-cosine filter to shape pulse of the generated PM-DQPSK signal, but it failed. I also tried to use the electrical raised-cosine filter to shape the driven NRZ signal, then to generate narrowband (25GHz) optical PM-DQPSK signal, but it failed either. Is there someone can tell me how to design a Niquist-filtered 100 Gbps PM-DQPSK transmitter? Thank you very much!
Best regards,
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December 11, 2014 at 9:54 am #16614
Damian Marek
ParticipantHello,
I fixed up your project and got it working there was problems with the transmitter!
Be careful when copying components from example files into a new project, because sometimes they will be referencing parameters that might not exist in your layout. For example I had to add a layout parameter called “rolloff” to your project so that the M-ARY Raised Cosine Pulse Generator would give reasonable results.
Moreover, careful consideration of the biasing and driving of MZM’s is needed. I added an electrical gain and bias to the inputs so I could copy close values from the example file. Then I played with the gain until I got good results. It is also possible to modify the gain and bias inside the parameters of the MZM, but I prefer explicitly setting the gain and bias before and only changing the Vpi of the MZM.
Regards
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December 11, 2014 at 11:17 am #16620
xiaoyong chen
ParticipantDear Damian,
Thank you very much for your help. Now the program works and I have successfully changed the bit-rate to 100 Gbps.
Thank you!
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December 12, 2014 at 9:07 am #16673
xiaoyong chen
ParticipantHi Damian,
Sorry for bothering you again. I have another question about Nyquist-filtered QPSK signal. In the last file you attached to me the Q-factor of the Nyquist-filtered QPSK is only 7, is it possible to improve the Q-factor to more than 10? Thank you!
Best regards,
Chen
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December 11, 2014 at 11:16 am #16619
xiaoyong chen
ParticipantDear Damian,
Thank you very much for your help. Now the program works and I have successfully changed the bit-rate to 100 Gbps.
Thank you!
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