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Confusion in setting Bit rate, Need Help ?

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(joined October 2014)
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Hi every one !
Hope u all are fine.

I am trying to send 1.25 Gbit/sec from each filter channel as u can see it from fig attached below (containing setting of Pseudo Random Bit where i have set the bit rate =1.25 Gbit/sec for each channel and scenario which contains complete setup).

But i have used initially Sine Generator of 12.5 GHz for Direct modulation and EAM, u can verify it from figure attached below of scenario.

Now the problem i am facing is that, the bit rate i want to send i.e 1.25 Gbit/sec is much lower then Sine generator frequency.

So kindly guide me whether,

1. Can I send data with this setting i.e data rate = 1.25 Gbit/sec and Sine generator frequency = 12.5 GHz ???
if not why ?

2. what should be my global setting for bit rate = ??

Either i should use 1.25 Gbit/s in global setting or i must use the Max repetition rate i.e. 12.5 GHz in global setting ??

Best Regards

Responses (5):

    • #19486
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      Ibn Aziz
      Participant

      Hi every one !
      Hope u all are fine.

      I am trying to send 1.25 Gbit/sec from each filter channel as u can see it from fig attached below (containing setting of Pseudo Random Bit where i have set the bit rate =1.25 Gbit/sec for each channel and scenario which contains complete setup).

      But i have used initially Sine Generator of 12.5 GHz for Direct modulation and EAM, u can verify it from figure attached below of scenario.

      Now the problem i am facing is that, the bit rate i want to send i.e 1.25 Gbit/sec is much lower then Sine generator frequency.

      So kindly guide me whether,

      1. Can I send data with this setting i.e data rate = 1.25 Gbit/sec and Sine generator frequency = 12.5 GHz ???
      if not why ?

      2. what should be my global setting for bit rate = ??

      Either i should use 1.25 Gbit/s in global setting or i must use the Max repetition rate i.e. 12.5 GHz in global setting ??

      Best Regards

    • #19511
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      Damian Marek
      Participant

      I would set the global bit rate to 1.25 Gb/s and just make sure that the samples per bit (which modifies the sample rate) is larger enough that you can represent the 12.5 Ghz signal.

      From Nyquist sampling theorem, you would need a sample rate of ~25 Ghz, which means your samples per bit would need to be at least 32.

      Regards

      +1
    • #19526
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      Ibn Aziz
      Participant

      Thanks ALot Damian, u clear my ambiguities.

      Best Regards

    • #19543
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      Ibn Aziz
      Participant

      Dimian,

      If i keep Global bit rate = 12.5 G Bit/sec, use RZ instaed of NRZ because it has twice bandwidth and keep Bit rate = 1.25Gbit/sec at Pseudo Randon bit Generator, then still its ok ?? Or i should change any parameter ??

      I am using samples per bit = 64 or above for this setup ??

      Is this still ok or i need any modification ?

      I am attaching pic of scenario below (consider RZ instead of NRZ)

      Best Regards

      Attachments:
      +1
      • #19560
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        Damian Marek
        Participant

        Yes I think it should be fine. A quick way to check is to use the RF Spectrum Analyzer to view the frequency content. You should have a peak at around 12.5 GHz.

    • #19615
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      Ibn Aziz
      Participant

      Thanks Damian Marek.

      Best Regards

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