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fiber looping

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(joined April 2015)
Spectator

Hi everyone..
Does the bit error rate increase when loops are used…i have to keep the fiber length upto 150 kilometers and i am using loops with 30 km for each loop…but when i compare the results with the case when i am keeping the fiber length equal to 150 km the results are varying with the case when i am using loop.. The BER is higher and is varying with each simulation when i am using loops..please help

Responses (33):

    • #33006
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      jyoti raina
      Spectator

      Hi everyone..
      Does the bit error rate increase when loops are used…i have to keep the fiber length upto 150 kilometers and i am using loops with 30 km for each loop…but when i compare the results with the case when i am keeping the fiber length equal to 150 km the results are varying with the case when i am using loop.. The BER is higher and is varying with each simulation when i am using loops..please help

    • #33058

      HELLO JYOTI
      The use of the loop control is to control the amount of laps on a circuit involving a fiber and a amplifier for example, it is easier to control the dispersion and prevents unnecessary usage of many amplifiers for many large distances…I would suggest you to go through the design which shown in the link i am posting…it makes use of loop control..

      Dispersion Compensation Schemes – A System Perspective


      Can u upload ur osd file
      Thanks and regards

      +6
      • #33107
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        jyoti raina
        Spectator

        hi fayiqa naqshbandi… thanks for the reply
        the link u had posted has designed a system where it has used loop control fr both fiber link as vl as opt. amplifier….i am using it only fr optical fiber bt here it is bit complicated and it has used 2 fibers in between…i am using a single fiber and my distance is 150 km and i hv kept loops = 3..can u tel me why BER shows variation….thanking u in advnce

        +1
    • #33088
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      Ranjeet Kumar
      Participant

      Hi Jyoti,
      I agree with you that using number of loops for fiber is not equivalent to its equivalent fiber size in terms of BER and Q-factor, but i think not very much difference occurs. It is because when we multiply size of SMF and DCF we have to change its parameters. But when we use no. of loops , its configuration remains unchanged and hence we get different results.

      • #33113
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        jyoti raina
        Spectator

        hi ranjeet…thanks fr ur reply.
        i have learned that we can use loops for multiplying the fiber distance using a single fiber but using a loop control..but i did not undersatnd what you meant when u said that when we multiply size of SMF and DCF we have to change its parameters… does using SMF and DCF have to do anything with loop control..please can u explain it.. thanks in advnce

        +2
    • #33111
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      MHD NA
      Participant

      it is easier to control the dispersion and prevents unnecessary usage of many amplifiers for many large distances…I would suggest you to go through the design which shown in the link i am posting…it makes use of loop control..

    • #33117
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      jyoti raina
      Spectator

      hi MHD…thanks for ur reply…
      it is helpful the way u explained..but i am not able to find the link…can u please upload any simulation file which has used loop control component for fiber only..i am designing a very basic system with loop control so it u can upload nay simulation file it will be very helpful…thanks in advance

      +1
    • #33123
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      Aabid Baba
      Participant

      Hello jyoti,
      All have rightly mentioned that what prime purposed of loop control are and what for you should use it. As far as your query is concerned , there could be various reasons why your two results are varying. I suggest you to first set alike parameters for every component you are using in your system design. Also try to disable the ‘generate seed’ option. logically , the results should not vary much. I hope you implement all these things and check for the results.
      Regards

      +1
      • #33138
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        jyoti raina
        Spectator

        hi aabid baba..thanks for ur kind reply..
        i have checked all the parameters and every parameter in the system i am making is same….what i am doing is i am using a loop control component to replace 150 km fiber in terms of loops…
        please cn u tel me what is this generate seed option and where i hv to enable it…does it increase or decrease bit error rate..
        thanks in advnce

    • #33142
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      Naazira Badar
      Participant

      Hi Jyoti Raina..

      Well the generate random seed option has got to be disabled so that your results stay consistent. Whenever you open component properties of a component, you would find a tab ‘random numbers’ in properties of some components, there you should disable the generate seed option. This way your results would always remain same no matter how many times you simulate provided all the parameters remain same. I hope it helps.

      Regards.

      +2
      • #33152
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        jyoti raina
        Spectator

        hi naazira…thanks for ur kind reply..it will be very helpful infact…please can u tel me where is this random seed generate option..i cannot find it anywhere…has it any significance in increasing or decreasing bit error rate or it just stops variations of the results..??
        please can u gv me the path where i find it..
        thnx and regards

    • #33145

      HI JYOTI..
      I agree with aabid..The first thing you must keep in mind is keeping the system parameters same for for both cases and also disabling the generate random seed option..As naazira has mentioned correctly that it leads to variation of results in most of the cases..you try these things and hopefully your results will not vary and there won’t be huge difference between the two cases..
      thanks and regards
      Fayiqa

      +4
      • #33160
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        jyoti raina
        Spectator

        hi fayiqa…thnx for sharing information it is rather very helpful…
        i will try to keep all these things in mind and see how my results come out…bt plz can u tel me where i hv to find this random generate seed option where i cud disable this option…i am vry much thankful to u people for such suggestions..it ll hopefully help me a lt..
        thanks

        +1
    • #33158
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      Naazira Badar
      Participant

      Hi Jyoti Raina..

      You could double click on a component. A properties window would open having many tabs like Main, Simulation . ‘random numbers’ would be one of the tabs. You can disable it there.

      As far as BER performance is concerned, it would always be different if seed is kept enabled, but no specific trend can be seen, as in whether it would increase or decrease. I hope I am clear.

      Regards.

      • #33162
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        jyoti raina
        Spectator

        thank u naazira badar…i got it it means it has no effect on the bit error rate and quality factor…it just makes our results fixed with simulation..am i right ?? i wil try to disable this option and check the results if they so any betterment.. do i need to keep it disabled everytime..or it is not ncessary..
        thnx

    • #33159

      Hi Jyoti raina

      As far as loops are concerned there are few links i am posting that might help u and regarding variation i would suggest u to disable random seed as suggested by all by double clicking on every possible components and you might find a random seed option that u need to uncheck that to disable random seed.

      Lesson 3: Optical Systems — WDM Design

      why use loop control in circuit

      Regards

      Burhan

      +9
      • #33164
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        jyoti raina
        Spectator

        hi burhan…i had gone through the link and it has amplifiers also…i am using only loop control for fiber distance only not amplifiers and moreover it is not simulation file..anyways i am thankful to u for sharing such info..
        thanx

    • #33161

      Hi Jyoti Raina

      Ohhhh here i found one more link infact a pdf that might give u a better insight of the optical loops. I hope it helps

      http://cdn.optiwave.com/wp-content/uploads/2014/10/1_2171.pdf

      Regards

      Burhan

      +4
    • #33187
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      Ranjeet Kumar
      Participant

      Hi Jyoti,
      First i accept your thanks in advance.
      I was discussing that using number of loops for fiber is not equivalent to its equivalent fiber size in terms of BER and Q-factor, but i think not very much difference occurs. It is because when we multiply size of SMF and DCF we have to change its parameters. But when we use no. of loops , its configuration remains unchanged and hence we get different results. for more explanation i am attaching osd file in which we use symmetrical compensation techniques (DCF+SMF+DCF)….. IF WE change the the length of fiber (DCF, SMF) independently change the length of fiber, we have to change its internal parameters but when change the no of loops the length of fiber increases without changing the internal parameters.

      Attachments:
      • #34682
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        jyoti raina
        Spectator

        thanx ranjeet sir..i checked it n it was realy of some help..thnx agn

    • #34692
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      SAHIL SINGH
      Participant

      Hi Ranjeet,

      I agree with your view that using number of loops for fiber is not equivalent to its equivalent fiber size in terms of BER and Q-factor.. You have expained the concept very beautifully… Thanks for your efforts

      Regards
      Sahil Singh

      +4
    • #34700
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      aasif bashir dar
      Participant

      hi all,

      the problem is to how to repeat the same trsnamission link again and again , which in other terms is called as fiber looping..

      in optisytem we have the provision to repeat the same fiber link again and again using loop compononent. after using the loop compomponent you edit no. of loops there.
      with the use of iteration, can view the performance analysis right from the first loop.
      suppose you want to evaluate the system perform with one loop to 10 loops for same transmission link…you can put iteration values there.and simulste the .osd file.
      you can get graphs which value with loop no. 1 to 10..

      hope this is help full

      with regards

      • #34886
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        Aabid Baba
        Participant

        Hello Aasif,
        I think it was already mentioned in previous posts too. I think you didn’t read previous comments.

    • #34711

      Hi Jyoti raina

      You are welcome. I want to clearify the confusion you have regarding me being male or female.. I would suggest you to check my profile to confirm that i am female and hence should be called madam rather than sir.. Haha this is really humorous of you to refer me as sir ..

      Regards

      Burhan

      +1
      • #34979
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        jyoti raina
        Spectator

        hi burhan mam..sry i didn’t know..thanx fr letting me that n ya thanx fr the help also.

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