Home Forums SYSTEM how to separate even and odd bit.

Viewing 15 reply threads
  • Author
    Posts
    • #25245
      Debanjan Sarkar
      Participant

      hi
      How to separate even and odd bit from a bit stream and i want the odd bit to be delayed by 1 bit period how to do that without using PSk generator and electrical signal time delay.
      i have tried with PSK generator and electrical signal time delay. when i used the delay block the last portion the odd bit stream is adding with the first portion but i donot need that.i want the odd bit stream to be shifted by one bit period i.e the portion from 0s to one bit period should be zero.i have the waveform that i need.
      Thank you

    • #25252
      Ashu verma
      Participant

      Hi Debanjan
      Interesting question,may i ask is this your own idea or requirement? Or you trying to reproduce some research article? If this is from research article then kindly attach the paper for better understanding
      Thsnk you

    • #25254
      alistu
      Participant

      Hi Debanjan,

      Since I cannot understand clearly what you intend to do (by delaying just odd shifts, the odd and even shifts are simultaneosly there), can you kindly introduce any paper you are doing the current work on the basis of? Thank you very much.

      Regards

    • #25259
      Damian Marek
      Participant

      I am not sure what you mean either. When you say odd bits do you mean binary sequences that make up odd numbers? Or do you want to split the binary sequence in two with every other bit in one of the two streams.

    • #25263
      Debanjan Sarkar
      Participant

      i want to implement MSK system on my own rather than using MSK modulation block.
      yes,i want to split the binary sequence in two with every other bit in one of the two streams.In MSK system i need In- phase bit and Q- phase bit and in the Q-phase i need to do delay by 1 bit duration . i have separated the bit stream using psk sequence generator but delay portion showing some problem. please check the attachment. and compare the q-phase output of my design and q-phase output of msk generator. Then you will find that my delay is not working properly and please suggest me how to get that delay as in msk generator.

      • #25264
        alistu
        Participant

        I think in this case, you can use two separate PRBS generators, and set the bit rate and sequence length in the layout parameters as half of what you intend to set for your whole system (for example, if your system should have a bit rate of 10e9, set the bit rate 5e9). And you can use two BER analyzers (or BER Test Sets) for the two PRBS generators (In case you use BER Test Set, you don’t need to use PRBS generators).

        P.S. There is no attachment to your post.

    • #25268
      Debanjan Sarkar
      Participant

      Thank you for your reply.
      sorry…here is the attachment.

      • #25277
        alistu
        Participant

        Thank you for attaching the file. I think you can do as I have suggested in my former comment. you can assume each of the PRBS generators correspond to either odd or even bits. And changing the bit rate in the way I told you would eliminate the need for using time delay. Finally, the use of a separate BER analyzing component for each PRBS ensures you can get the total BER by using the mean value of the two BER values.

        Regards

    • #25276
      Debanjan Sarkar
      Participant

      Hi alistu
      I have attached the osd file please check and help me.

      • #25278
        alistu
        Participant

        Refer to #25277 please.

    • #25281
      Debanjan Sarkar
      Participant

      Thank you Mr. alistu.

      • #25282
        alistu
        Participant

        You’re welcome!

    • #25326
      Debanjan Sarkar
      Participant

      Hi Alistu
      I have understand what you have written in your earlier comments. But i need one more help from you can you suggest me how will I get wave from as in Q-arm of msk genertor from my design as i have already attached. I think i am getting the waveform in I-arm and also getting the waveform in Q-arm also but delay block is giving some problem.what parameter i have to change to gave the desired waveform after delay.please help.
      please find the attachment of .osd file and my output and desired output. visualizer 7 shows my output and visualizer 17 showing msk generator output of Q -arm.

      If anyone have the solution then please help.
      thank you

      • #25398
        alistu
        Participant

        Hi Debanjan,

        Unfortunately, I can neither figure out why the delay component is not making any delays. I even used another delay component after the sine wave generator and still, the visualizer shows the signal beginning from zero (in time domain). I will let you know if I manage to solve the problem.

        • #25431
          Debanjan Sarkar
          Participant

          Thank you for your reply.
          Is there any one who is from Optiwave?? May be he can do something related to this

      • #25442
        Damian Marek
        Participant

        If I were you I would use the Serial to Parallel component for making the two separate bit streams. Also as mentioned in other posts the “Delay” component is a bit confusing but it does not introduce a time delay. It is used to create a null signal for bidirectional components so that they can be simulated. You should be using the Time Delay component in the Passives Library.

    • #25448
      Debanjan Sarkar
      Participant

      Dear Damian Marek,
      Yes, I am using the delay from passive library. What delay shall i use to get the desire output??please explain.

      Actually i am working on MSK and i Have implemented it in MATLAB and now want to implement the MSK modulation step by step in opti system. so i followed the inbuilt structure of MSK modulation that is in the component library and there is delay. PLease see the attachment in replay #25326 above. I have attached the step by step .osd file inducing the MSk generator.
      I am getting the waveform in my design like MSk generator in I- arm. But I am not getting the output waveform in Q-arm as per the MSk generator. I have attached the waveform also.
      Please check and Inform me if i have done anything wrong in design as i need to implement this urgently.

      As you have mentioned in earlier reply “Delay” component is a bit confusing.please explain me as i want to clear the concept.
      Thank you.

    • #25449
      Debanjan Sarkar
      Participant

      Dear MArek,
      Is there any serial to parallel component in optisystem?
      Thank you

      • #25451
        alistu
        Participant

        Hi Debanjan,

        The serial to parallel component is there in the signal processing library, in the “Binary” folder in the “Tools” section. However, I think it has been added since Optisystem v. 9 and therefore you can’t use them in v.7 (but please check for it). As for what you asked about “electrical time delay” component, I can access it in version 13 in “passive library” and inside “electrical” folder. It has the same function as what you were looking for here, so there should not be any confusion.

        Regards

    • #25452
      Debanjan Sarkar
      Participant

      Dear alistu
      I have used the electrical time delay from passive library-> electrical folder as you can see from .osd file. is there any delay component which can delay the signal by one or required time duration as required in my design?
      thank you

      • #25465
        alistu
        Participant

        You’re right. I have addressed the component Damian has proposed, but you have already used it. This is the component that is supposed to make the delay you want to make, according to Damian’s statement. The other component, “Delay”, is the one Damian has probably thought you had been using.

    • #25467
      Debanjan Sarkar
      Participant

      thank you alistu
      may be.what you told is right.but i need the delay which can shift the signal by one bit. I am trying my level best to find the solution but unable to solve the problem why delay is not working?need help from Damian. may be he can help.
      thank you.

      • #25605
        Damian Marek
        Participant

        The Electrical Signal Time Delay is working for me. The scale of the attached photos is in bit period and you see the edge shift from the 2 position to the 3 position, demonstrating the proper delay. It might be hard to see visually because your sequence length is so short and the samples per bit is pretty low. The other thing that could be confusing you is the PSK Sequence Generator is slowing the symbol rate from “Bit rate” to “Bit rate/2”.

    • #25788
      Debanjan Sarkar
      Participant

      Thank you Mr. Damian Marek
      Actually i am also getting the same waveform as you have send.
      But in this case the last portion of the signal is coming infront of the first bit.But i need the signal should start after the delay duration. please see the attachment for better understand my problem what type of delay actually i need.
      Help me and suggest me what to do t get such signal.after delay.
      thanks

      • #25848
        Damian Marek
        Participant

        I see, thanks for the explanatory picture. This is expected operation of the component because since the computer program can not represent an infinite time window any data that is delayed passed the largest time is simply looped back to the front. You will see this also happens in long fiber simulations with lots of dispersion.

        A simple solution would be to increase the layout parameter sequence length to a larger value. Then in the bit sequence generator changed the leading and trailing zeros to a large enough value that the bits sequence can be delayed without reaching the end of the time window.

        Regards

    • #25921
      Debanjan Sarkar
      Participant

      thanks for your reply . please see the attachment.

      • #26024
        Damian Marek
        Participant

        The only difference between your signals is that delay section which ends up have little effect on the demodulated signal. The MSK Pulse Generator is probably hard codes to output the 0 signal for the first bit period while the delay component does not work like that.

        If you really want the exact same signal you could use an electric multiplier as in the attached project to force it to 0. I multiply it by a bit sequence of “011111111” because I changed the total bit sequence to a longer one.

        • #26028
          Dr. Dhiman Kakati
          Participant

          Hi Damian,
          the design file you have attached in reply no. 26024 is using MSK sequence generator but the constellation is not that for MSK.
          please check once.

          Regards

    • #34176
      Sanjeev kumar
      Participant

      w can we use the component in reverse as said in the replies?

Viewing 15 reply threads
  • You must be logged in to reply to this topic.