Home Forums SYSTEM bit rate

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    • #19911
      faysal sarker
      Participant

      what is the meaning of the two bit rate at the given attachment.and which one is the data transfer rate?

    • #19914
      Dr Rk Sethi
      Participant

      1st one is the Global data rate and second is the PRBS generator data rate.
      The data transfer rate is given by the PRBS generated data rate.

    • #19916
      Ravil
      Participant

      Hi faysal sarker,

      As it has been noticed correctly by Rk Sethi, the first bit rate (from Layout 1 Parameters table) shows data transmission rate through your whole system (from output of your transmitter to the input of your receiver). The second table shows the bit rate of data generated by information source and launched to your transmission system. These two bit rates are differ due to implementation of different multiplexing and modulating schemes as well as the signal coding.

    • #19932
      Abhishek Shrama
      Participant

      Hi ,I have also a Doubt,In case if we do not use script mode in PRBS and enter data rate in PRBS at normal mode then on which data rate system perform ? Can we disable a Bit rate in global parameter window.Can we put iteration on Data rate in same layout?

      • #20140
        Ravil
        Participant

        Dear Abhishek,

        In my opinion, script affects the Global data rate first. As I indicated below, this data rate can be calculated through ‘the time window which, in its turn, is a sequence length over the generated bit rate’. I don’t think that you can disable the Global data rate since it is used for the calculation. However, I am not sure if that option is available in the last versions of OptiSystem. Not sure what you mean by ‘iteration in data rate’…

    • #19950
      Ashu verma
      Participant

      Well said RK sethi and Ravil.Abhishek if you use script mode then it use the data rate of system.If you use normal then this is the data rate of PRBS but system data rate is, as in global parameter window.Am i right ravil and Sethi ?

      • #20142
        Ravil
        Participant

        Yes, Sam Sung. The system data rate is in the Global parameter window and the data transfer rate is given by the PRBS.

    • #20125
      faysal sarker
      Participant

      please give me some source from where i can get explicit information regarding Global data rate and the PRBS generator data rate.

    • #20139
      Ravil
      Participant

      Hi faysal,

      I am pretty sure that the information you are requesting can be found in OptiSystem manuals. The example of Global data rate usage is shown in Lesson 6 (if I am not mistaken) online. You can also check the optsystem documents for the information about global parameter window optisystem>documents>global parameter. In general, you can calculate the Global data rate through the time window which, in its turn, is a sequence length over the generated bit rate.

    • #22081
      LALIT VERMA
      Participant

      By this discussion can i interpret that while design a system global parameter bit rate can differ from prbs generator specially for sac ocdma system.

      • #22103
        Ravil
        Participant

        Hi Lalit,

        Yes, you understood it right. These two parameters can be different.

    • #22091
      Taiwo Ambali Abiola
      Participant

      I think the explanation is still the same. Any parameter on a component or “module” run on a “script” automatically takes value from the global parameter. However, when such parameter is set on “normal”, it takes the manual value set for it. Read more about it in the documentation. When a module parameter is set on “script” and the value there is pointing to a parameter available on “global parameter” such as (bit rate, sequence length, time window, sample per bit and etc), it automatically take the value from the “global parameter”.

      A bit rate is the one you set on the PRBS either by accessing global parameter bit rate or through “normal” setting. it is possible to be different from the global parameter bit rate if you change it to “normal” and you assign a value. I hope is a bit clear?

      • #23303
        K. Esakki Muthu
        Participant

        Ravil,
        if you keep global bit rate and the PRBS bit rate then we can get proper results i think. that should be same for getting proper eye diagram and BER? Am I right?

        • #23305
          alistu
          Participant

          Hi Esakkimutho,
          I don’t think that’s necessarily correct. The bit rate applied to the implemented system is the one defined in the PRBS, and not the one in global parameters. We had a discussion in which there was another bit rate defined for PRBS, which you can read in here:

          Sac ocdma with MD code

        • #23499
          K. Esakki Muthu
          Participant

          Dear Alistu,
          I have tried this personally, if we keep Global bit rate and PRBS bit rate different, then the results are different.

        • #23500
          alistu
          Participant

          Dear Esakkimuthu, Very carefully I used the word “not necessarily” about what you have mentioned in your previous comment. The reason for what you have experienced is that the global bit rate defines some other global parameters and in some cases, this might cause problem. I have also experienced such cases, but in many cases it was ok.

    • #22092
      Taiwo Ambali Abiola
      Participant

      As for SAC-OCDMA, I think it is a function of how many transmitting points you have. For instance, if you have 4 transmitters, and each PRBS is running with 10Gbps bit rate, the overall data rate is 10X4 which is 40Gbps. I stand to be corrected if I have made mistake please.

    • #22106
      Ashu verma
      Participant

      Hello Taiwo
      You explained very well about the confusion regarding Bit rate for script mode and normal mode.Also the concept of total bit rate after multiplexing of no. of channels is right explained by you is right.Ravil gave some good points and links given by alisthu are very important for any beginner to use optisystem.

    • #22115
      Taiwo Ambali Abiola
      Participant

      Really! Thanks alot Sam sung

    • #22116
      gaganpreet Kaur
      Participant

      First one is the bit rate which goberns the complete system while pseudi random geebrator bit rate specifies the bit rate to b used by the transmitter.this bit rate is rate of input sequence generated which will modulate the laser source.

    • #22947
      Gurpreet Kaur
      Participant

      i hve a query related to same that if my prbs bit rate is 4gbps and i am using 3 users, then the global parameter bit rate should be set to 12gbps?
      and at the receiver side if i am using low pass bessel filter for single user then which bit rate is to be used for setting its cut off frequency? as in filter it is in script form 0.75*bit rate. so i shall simulate with prbs data rate or the global one?

      • #22950
        alistu
        Participant

        Hi Gurpreet, What you must do is to set the bit rate in global parameters to the bit rate of each user, which is 4 Gbps in your case. Then be careful that random sequence bit generators you use have their bit rates determined in script mode and the script should refer to the global bit rate, which it is on default.

    • #22951
      alistu
      Participant

      You have asked about the filters’ cut-off frequency. If you are using the filters for each user, you must as well consider the bit rate of each user in this case. The “bit rate” mentioned in the script of the filter is also the one that is determined in the global parameters. So setting the value of every parameter which might be used in many components in the global parameters and using the script mode for them can sometimes be really time saving, so you would just change it in the global parameters and its value changes for all of the components.

    • #22964
      Ashu verma
      Participant

      Hi Gurpreet
      Alisth have explained well about your question.I just want to add that run your system with script mode and change data rate in global parameter window.For filter(electrical low pass) ) 0.75*Bit rate is a cut off frequency,you can change it to o.8* bit rate and see the results beacaus for my some of systems it works well.In optiwaves example of CSRZ,MDRZ and DPSK they have considered cut-off frequency 0.8* Bit rate.

    • #22968
      Gurpreet Kaur
      Participant

      thanks alistu and sam sung for this.

    • #23577
      Ashu verma
      Participant

      Welcome Gurpreet
      All the forum participants are here to help each other.Please also participate more and help other new members as well as senior members.I am glad that suggestions made by me or from other senior members help you.Beat of luck for your future research work.Share more,Guide more and Learn more

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