DDO-OFDM with OS12 OFDM components

[alistu]

Hi all,

I am trying to get the Optisystem direct detection optical OFDM (DDO-OFDM) sample osd file to work with Optisystem 12 OFDM components. So I have replaced the Optisystem 13 OFDM components with those of Optisystem 12, and I have also made some changes that I thought were necessary to the BER Test Set. But I can’t seem to be getting an acceptable answer from this implementation, even when I do the simulation for a back-to-back system and lower the bit rate. Please provide the necessary changes to the file so that it would give the results. hank you in advance.

Regards

[Ashu verma]

H! Alistu
I am not able to open the file attached.Every time i try to open file attached by you,i have same problem.All the files which simulated in latest version that easily open in my trial version.I can’t understand why it is so.I have tried with the way you mentioned in one of the forum topic but end up with no results.

[alistu]

Hi Sam,

The problem that is mentioned a couple of times in other forums occur when my file is saved in doc format. But here I have attached it in osd format and have been solved. I think it would be better to see if others encounter the same problem by using Optisystem version 13.0.3. If they can’t open it either, the problem is from my software. Otherwise, it’s from yours.

[Ashu verma]

Ok,I got the problem,I think since you have the 13.0.3 , so these updated files could not be open by trial version.It seems to me like this.I have attached a screen shot for what error system gave to me

[alistu]

If you are also using Optisystem version 13.0.3 like I do, then I don’t think the problem is from your software. As far as I am concerned, the 30-day trials of Optisystem function like a full version and I think this is mentioned at the start of the installation of the program if I remember correctly.

[Ashu verma]

Once i got same problem when damian attached file in Twdm pon.But damian then said that trial version is capable to open these files.But i couldnt at that time too.We will see the problem in my system or other member face it also or not.Thank you Alistu

[alistu]

If Damian has confirmed such a thing, then the problem is not most probably from my file. However, if somebody else faces the same problem, I will attach a new osd file, but it should work fine according to my experience.

[Damian Marek]

Hi all,

I successfully opened your project Alistu and I am using 13.0.3. I believe the problem may be that Sam has a slightly older version. Same what does the About window say about your version number?

[alistu]

Thank you Damian for checking the file and verification. Can you please help me with the implemented system if it is possible? I haven’t made any changes to the DDO-OFDM sample file except using OS 12 OFDM and unticking “using OFDM” option in BER test set, so it’s supposed to be working. Thank you again.

[Ashu verma]

Damian you may correct ,i think i have downloaded the version i am using ,a some time ago ,almost 5-6 months but run now.May be this would be the case.

[alistu]

Here I have attached another file from the same system, only with additional spectrum analyzers. Another thing I find strange is that the RF analyzers only show the range of 0 to 20 GHz. Even when I assign a frequency out of this range to quadrature modulator, the RF spectrum analyzer_2 (the one right after quadrature modulator) shows the signal with center frequency within the aforementioned range.

[Dhananjay Patel]

I have observed one issue with the downloading and opening of .osd files. Ifweare trying to download and open the file in mozilla then, it does not gets open. However when I tried using it with google chrome, the file is downloaded and open for working.

[Dhananjay Patel]

Dear Alitsu,

I have checked ur design and am not able to find the error in the same. However I am attacheing two of my design using )S12 components. I hope this helps.

First is the simple OFDM modulation and demodulation. the second one is the with optical uconversion. I am able to get the spectrum at the photodetector correctly. I hope you can make changes as per your requirement.

[Dhananjay Patel]

here is the another file

[alistu]

I appreciate your help, Dhananjay. As I mentioned, I have used the Optisystem sample file and for the default bit rate, the system is working. It seems that what I refer to as “the problems” are there in your implementations, too. Besides, when I change the bit rate to one GHz in your file, the simulation stops working with an error and the software closes. This is not my concern, though. Thanks again for your help.

[Dhananjay Patel]

Dear Alitsu,

Can you tell us, what design are you planning to implement. What will you do once the OFDM system is implemented. May be I can help better.

[alistu]

Dear Dhananjay,

Currently I am trying to get the acceptable results from the implementation I have attached, which is the Optisystem sample osd file for direct detection O-OFDM without version 13 OFDM components. I simply want to be able to change the bit rate and get appropriate results (not necessarily good results); Results that assure system is working fine.

[Dhananjay Patel]

Dear All,

I would like to ask an open question to all. When we try to implement a system on optiwave and if we get the outputs well. How do we decide that the output which we have got is correct.

We need to have a mathematical modelling for the same. This can be done in matlab. for mathematical modelling, we need to have equations for the entire system. Can optiwave provides us with the equations which they have used to implement the following blocks. (For eg. If I am trying to build OFDM system with optical transmission, then I need to have the equations for all the blocks used to design the same. Then I can write those equation in matlab and get the mathematical modelling for the same.)

Please correct me if I am wrong or provide some more information towards working of this step.

[alistu]

If my perception is correct, you want to have a way to check the results. The components available in Optisystem are supposed to be based on mathematical models of the real components and the information about which papers or references have been used for modeling are available at the help section of the components. I think if you want to see if a system is working fine, you can simply compare the results to those of a paper. In case one is not working based on a paper, they should use their general understanding of the system to determine whether the results are acceptable or far off the limits. Implementing all components models in Matlab is really hard and time consuming.

Regards

[Abhishek Shrama]

Hi Dhanajay
Your suggestion is good and this may be preferred to test the system performance.I have seen mathematical and simulation results comparison in many papers from some journals with good index.But as far as mathematical testing is concerns, don’t you think it is difficult to test every time about simulation.Optisystem made it user friendly software by using matlab and i have used some other softwares too for same purpose,but optisystem is very easy to use.
For you second question ,if you want the mathematical calculation of all the components then go to component > double click then at bottom of page there is reference from which that component realized. In case there is no reference than you may ask optiwave for the equations.Most of the equation described in help tutorial also.
But i like the idea which you suggested.
Thank you
P.s Fortunately we have given somewhat same answer Alistu ,simultaneously 🙂

[Dhananjay Patel]

I agree with you guys. But during presentations if you show simulayions results using a software people ask for its mathematical or hardware validations. Hardware validation is not possible due to lack of infrastructure and mathematical is difficult to achieve

Let us together, try to find a way out

[alistu]

You are right Dhananjay. However, the only practical way I can think of is to rely on our own knowledge of the system, based on which we expect certain results. If the results are very different from our expectations, then we might ask Optiwave team if the component is working right.

[Abhishek Shrama]

Dhanajay, I can understand what actually problem is? Alistu, confirmation for our work by ourself is one thing,but most of the times teacher require some proof that work is authentic or not.The two ways to get the confirmation is to realize a hardware of the same system which seems impossible, other is mathematical modelling to compare with simulation results.
Moreover may be you can choose a method to numerically check all the components from help, make a blue print of simulation in mathematical form and match the results. All formulae are given in components and cross check your results
May be it can help you theoretically.

[alistu]

I understand Dhananjay’s problem and as I have stated, the problem with mathematical modeling is its being not practical. Otherwise, can you please check the system I have discussed on this topic by mathematical modeling and numerical calculation of the optical wave passing through a 50km-long fiber with different nonlinearities and chromatic dispersion and so on? The modeling of such channels is what Optiwave engineers have done and now we wish to use their products to avoid these modelings.

However, now I can think of another option: to implement the design and check it with another software. Even doing this, I don’t think we would be able to get the same results as the ones obtained with the first software, but still it’s double-checking if someone is interested.

Regards

[Dhananjay Patel]

Dear Abhishek,

what you meant is correct. Here in research, the examiners always ask for the mathematical validation. Mathematical validations is compulsory. Hence cannot be avoided.

Moreover If we try to implement this equations of whole system, it would be difficult to do so and thus not possible to sohw our results validations.

Dear Alitsu,

Thanks for the help.

I would request all other forum members if they can help with some hardware facility in their organization for visiting students. This will help to create good bonding between the organizations and students too.

[Abhishek Shrama]

Thank you Dhananjay for quick response.Alistu also gave a good point of checking the simulation with other software too,but still validation is on software.Faculty also asks for mathematical proof as stated above.We dont if it only persists in indian universities or in other countries too.
As far as hardware part is concerned than i think it is little difficult to allow students in their colleges for work.But i have seen many government bodies in india which allow students to work in.Some of the organizations are central scientific instrumentation organisation(CSIO),National institute of technical training and research (NITTTR), these organization has many research labs in india and even allow students at their applications.
Thank you

[alistu]

As I mentioned before, I understand the reason for what what Dhananjay suggested, but I don’t think it’s practical. I’d be grateful if you answer the question I raised in my former comment: Can you please check my above system with mathematical methods and tell if the answer given by Optisystem is correct?

Cheers!

[Ashu verma]

Thank you Dhanajay for consider and post this important point to discussion.I have gone through all discussion and there are some good points like cross checking of system on other similar software.Also one of forum member suggested about rough calculations of system by using formulas from help section.I think it would be difficult to calculate all the value numerically however with correct knowledge and deep study may this happen.But for begginer like me 🙂 it is quite difficult to solve complex equations.

My simple suggestion is that we can make the system and get crosschecked by forum members by posting system on forum.However this may have some problem regarding research and sharing the concept and system with others.But rough systen can give the overall idea.I assume that Damizn also checks the answers given by members and posted systems too,.
For more ways we need to get answers from other members too.
Regads

[alistu]

Since I am a “beginner”, I believe that’s the reason why I can’t check the system using mathematical methods. Otherwise, all experts first run a simulation using a software and then start to solve the equations one by one to see if the simulation results are reliable 😉

However, I don’t think I’d like my system to be checked mathematically as much as I can use help to overcome the problem I have started the forum for. Thank you all in advance.

[Ashu verma]

Good one Alistu 😉 Thank you

[Dhananjay Patel]

Dear Sam,

I completely agree with what you have suggested. What can we expect from optiwave team is to provides us with the necessary equations of the system if we send our designed system to them. Once they provide us with all the equations, we can try to simulate them mathematically over the matlab.

I know that the equations are available in the help section of all the components block, but if the optiwave team provides us with the exact equations then lot of time will be saved. They can study the design and provide us with necessary equations.

Thanks Alitsu,

Me being a beginner too, becomes very difficult to check the results mathematically. So the suggestion by me and Sam might help for the mathematical validations.

[alistu]

I think having the equations is one thing, solving them is another. For example solving nonlinear Schrödinger equation for the light passing the fiber requires numerical calculations and takes a great deal of time. But please let me know of the results if you ever tried such a method for checking your simulations. Thank you.

Regards

[Ashu verma]

Thank you Dhananjay for your appreciation.This is a basic and very serious problem with our universities to get a proof or mathematical validations for work that we have proposed in research work.Somehow this is important to validate the work.Problem now days is that you can publish your work and there are many journal which give you acceptance even for work which not new or sometimes not correct.So for collages it become necessary to ask for a proof for secure side.
Again problem revolves to the calculations,as Alitu said above.Hope there will be easy way out to solve this thing.
Checking on different software again consumes very much time,because in the span of six month it is very difficult for student to learn one software and learning and checking in different software again make system hard.

[Dhananjay Patel]

I totally agree with Sam and Alitsu. If I ever will try to deal with mathematical validations, then I will put across the step done to achieve the same. I suggest We should together try and implement all this validations and also try to help each other.

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