BER analysis of OD8PSK

[Mohammad Boroon]

Hello,

I downloaded the OD8PSK module from optiwave website and am using it. The problem i am facing is that the module cannot define a BER on an eye diagram. I cannot get the module to work logically. Because BER analyzers only show a 0 for BER and the eye diagram analyzers are also not showing the correct BER for a b2b condition. I re-arranged the module as shown in attachment and the BER analyzers show a eye diagram which is correct but BER is always 0. Moreover if a medium is added the eye diagram doesn’t change and neither the BER which means the medium isn’t affecting the detected signal. Anyone knows how to fix it?

Attachments:

1. 

   OD8PSK.tif
   

[Damian Marek]

This is a common misconception about the use of the BER Analyzer and Eye Diagram Analyzer for higher order modulator formats. Please search the forum for BER Test Set and you can find many similar topics.

Briefly, the BER Analyzer in the example is set to Measured mode, so it is not using the eye diagram it is only comparing the detected and transmitted sequences. The eye diagram looks strange and the BER does not change because it is not counting any errors. Probably because the sequence length is so short and the true BER is so small that there are no errors.

Also the eye diagram analyzer works well for RZ/NRZ OOK systems but it doesn’t correctly calculate the BER for higher modulation formats. IT is only there as a tool to visually inspect the eye diagram.

Regards

[Mohammad Boroon]

Thank you Damian,
The thing is i don’t know exactly how to parametrize my BER test set for OD8PSK. I tried using it for 1 of the channels using instructions in https://optiwave.com/resources/applications-resources/optical-system-ber-calculation-using-the-ber-test-set/
I am using Optisystem 11.0 by the way. so i enabled single iteration and run it, but the BER was wrong. I tried it with different sequence lengths and etc but it didn’t show me BER yet. I attached the file here. could you please tell me what’s not right?

[Damian Marek]

I can’t find your attached file, could you please attach it again?

[Mohammad Boroon]

oh sorry, there was a connection issue i guess. here it is.

Attachments:

1. Optical-Differential-8-Level-Phase-Shift-Keying-OD8PSK.osd

[Damian Marek]

I ran your simulation and after a very long time I got the the simulation completed without any Bit errors which is expected for a back to back system. What do you mean the BER was wrong?

[Mohammad Boroon]

Thanks Damian,
May i know what order number you used? single iteration or more? And may i know which version of Optisystem did you use? Did you get a Log of BER of a Back-to-Back system of a very negative number (say -50, -100)? Because i still can’t get it to work. it shows a log-of-BER of -0.303 all the time (back-to-back and after introduction of fiber).

[Damian Marek]

I ma using the most recent version of OptiSystem 13.0.3 also the Log I get is -1000. Try using the PSK modulator and encoders instead of this really complicated example. The simulation will be much faster. You should of examples even in your version of PSK modulations.

[Mohammad Boroon]

Sorry for the late reply Damian. I tried running it using a version 13 but i still can’t get a -1000 for log-of-BER. Can you send me the file that you ran? did you make any changes in the file i sent you? yeah this is a quite complicated example but i wish i can get it to work because i really really really need it for my project. thanks

[Damian Marek]

Unfortunately, I can’t send you my file (which should be exactly the same as yours because I did not change it at all) because since my OptiSystem version is more recent yours will not be able to open it.

[alistu]

Hi Damian, Considering the fact that Optisystem trial version can be installed on every computer for thirty days, can we also install the new version trial, for example v.13.0.4 after its release for thirty days on the same computer as we had installed v 13.0.3 before? (I know we can install version 14.) Thank you.

[Damian Marek]

Hi all,

You can re-evaluate major releases only. E.G. You could download 13.0.2 and then a couple months later download 14.0, however you can not re-evaluate point releases. You could not download 13.0.2 and then download 13.0.3.

The smaller point release notes are sent out to users by email and we only put major release notes on the website. You can email support@optiwave.com and ask for the OptiSystem 13.0.3 release notes.

Regards

[Taiwo Ambali Abiola]

Hi Damian, Thanks for your usual support. How can we get the PdF documentation for optisystem version 13.0.3. We currently have version 13.0 and would like to have information on the latest version.

Thanks

[alistu]

Hi Taiwo, If by PDF documentation for Optisystem version 13.0.3 you are referring to the release notes, it is there in the following address:

https://optiwave.com/download-1/optisystem-13-0-3-release-notes/

There are installation notes, software and hardware compatibility and list of updates and changes in the components there.

[Ashu verma]

Thank you Alisthu for link as it is almost cleared the new updates by optiwave.Now we are waiting for optisystem 14.Hope it includes some other components like MDM,FMF,PCF etc.

[Taiwo Ambali Abiola]

Interesting issue raised by Muhammad Boron., However the topics relating to the usage of BER test set in place of BER analyzer have been discussed previously in some of the earlier posts. Any of these might be beneficial to you. I think you have to check the components property of the BER test set before you can actually read the received BER information.

DPSK with optical modulation

WDM QPSK THROUGH FSO LINK

OWC QPSK Design

visible light coomunication

https://optiwave.com/forums/topic/how-do-we-connect-bre-analyzer-to-a-dp-qpsk-reciever/ and several others.
enjoy!!!

[alistu]

Hi Taiwo, Thank you for the links and the willingness to help. However, I went through the links and did not find the answer to the exact question Mohammad has asked. I believe it would have been much more time saving if you had just copied the relevant answer that you had found in the previous forums in here as well as the links. Othewrwise it is easy to find all these forums just by a google search, but finding the one that is the answer in here is tricky. Thank you again for your help.

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