- This topic has 5 replies, 2 voices, and was last updated 10 years, 6 months ago by
Damian Marek.
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May 8, 2014 at 12:23 am #11395
Bindu
ParticipantHi all,
Am looking for a complete design of duobinary modulation and demodulation system and working of it.
Please help me out.
thank you for the help.
Bindu
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May 12, 2014 at 2:20 pm #11452
Damian Marek
ParticipantHere is an example of using duobinary modulation in OptiSystem. These are back to back systems, so all you need to do is add a transmission section to the design.
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May 13, 2014 at 9:04 am #11464Participant
Hi Damian Marek,
I appreciate your great help.
Can you also please help me out in more doubts in Optisystem.1) Theoretically for LEO/GEO satellites has min BER of 10^-9 to 10^-12.
but when am trying out designs like QPSK,BPSK,Duo-binary systems in eye diagram analysis, Min BER shows ‘0’.
how can i vary it or change it.2) In optisystem in ‘report’ where we can view graphs. Is there any possibility to compare to parameters like BER vs Eye height etc..
How can i acheieve that.Please go through and help me out.
As am running out of time for my project submission. am looking for more information on Optisystem.Please assist me on the priority.
Thank you for the help.
Bindu
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May 13, 2014 at 11:39 am #11478Participant
Hi Bindu,
There are actually a couple ways that would make your BER 0. For example, the Duobinary design I sent earlier does not have a significant source of noise. To get a more realistic BER try adding a transmission link, like an Optical Fiber or a source of noise, like a White Light Source.
You also have to be careful with which component you are using, which could be the BER Analyzer and Eye Diagram Analyzer or the BER Test Set. The first two calculate the BER by directly analyzing the eye diagram. The test set actually compares the generated bit sequence and the bit sequence recovered at the output of the system. For all of these components the bit sequence length plays an important role on the accuracy of the calculation/measurement, especially for the test set since it is possible for bit sequence lengths of less than 1000 to almost never have a bit error.
Are you interested in plotting the BER vs Eye height and how it relies on the decision instant? Or do you want to plot the BER vs Eye height for systems with different noise levels or laser powers?
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May 13, 2014 at 12:18 pm #11483Participant
Hi Damian Marek,
Thank you for the quick response. Info was helpful.
Yes i want to know both of them “plotting the BER vs Eye height and how it relies on the decision instant and plotting the BER vs Eye height for systems with different noise levels or laser powers”
To make it more clear. Am doing my project on “Design & simulation of QPSK modulator for optic inter satellite communication”
So now that i have QPSK design, I want to compare with other systems (BPSK,DUO binary,etc) and to show that QPSK is superior compared to others.
So i need some graphs with respect to parameters like BER,Q factor, wavelength,eye height, power etc.Sorry for the trouble. Please assist me on the following.
With regards,
Bindu-
May 13, 2014 at 3:26 pm #11493Participant
Hi Bindu,
There is a great tutorial on how to perform Parameter Sweeps in OptiSystem at the following link:
It is also relevant to your questions as the tutorial shows you how to sweep input power and produce a graph of the BER. To get the BER as a function of Eye height you can just sweep through the Decision Instant parameter and then plot the min BER as a function of Eye height.
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May 16, 2014 at 8:08 am #11603
ANKIT
ParticipantYes Bindu,
Damian is right. You can apply sweeps for any parameter like input power, distance etc.
You can also do one thing, prepare one design (operating at 40 Gbps or you can go for WDM network if higher speed is required ) then apply sweeps to the two parameters : input power and distance.
for e.g. input power = -5, -3, -1, 0, 1, 3, 5 dBm
Distance = 50 Km x N spans (N = 1,2,3,4,5,6,7,8,9,10…..up to 100) , so total distance will be around 5000 kmNow simulate this design with three different modulation schemes : BPSK, QPSK and Duo Binary
I think, this will give sufficient no of results for your thesis or project submission. You can go for comparative analysis of all three modulation formats and come to know that QPSK is good.You can refer one paper also which also give the same kind of comparison but with three different modulation formats. here is the link:
Regards,
Ankit
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