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On Which Factors Cut Off Frequency Of Rectangular Low Pass Filter Depends

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(joined March 2015)
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Dear Members
I have two questions please guide me.I am working on Radio over Fiber System.

(Q-1)–I want to inquire On Which Factors Cut Off Frequency Of Rectangular Low Pass Filter Depends
When i set cut off frequency 0.1*Bit rate then it shows good eye diagram while when i move towards 0.2*Bitrate—–0.75*Bitrate the eye diagram gradually starts rough and distorted???

(Q-2)–is it practically possible to set the cut off freq 0.1*Bitrate or 0.2*Bit rate or 0.3 *Bitrate???

Best Regards

Responses (4):

    • #18411
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      Abdullah Baig
      Participant

      Dear Members
      I have two questions please guide me.I am working on Radio over Fiber System.

      (Q-1)–I want to inquire On Which Factors Cut Off Frequency Of Rectangular Low Pass Filter Depends
      When i set cut off frequency 0.1*Bit rate then it shows good eye diagram while when i move towards 0.2*Bitrate—–0.75*Bitrate the eye diagram gradually starts rough and distorted???

      (Q-2)–is it practically possible to set the cut off freq 0.1*Bitrate or 0.2*Bit rate or 0.3 *Bitrate???

      Best Regards

    • #18418
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      Ravil
      Participant

      Hi Abdullah,

      In general, the cut-off frequency of any low-pass filter depends on 2 parameters: internal resistance and its capacitance. Rectangular filter is considered as an ideal filter in this case, I think.

      This cut-off frequency defines the passband of your signal. Your bit rate will be defined by signal bandwidth and type of coding you are using.

    • #18721
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      Heitor Galvao
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      The Bessel filter transfer function depends on two factors of insertion loss and order parameter of a normalizing constant. While the transfer function of a rectangular filter depends also on the insertion parameter, depth parameter, a center frequency and bandwidth.
      It is interesting to note that in the “help” of the Bessel filter he makes an important observation:
      Important: Previous versions older than OptiSystem 7.0 used a different equation to estimate the 3 dB bandwidth. The following table provides the multiplication factor that has to be multiplied by the current bandwidth in order to obtain the same results of versions older than OptiSystem 7.0:
      (attached image)

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    • #18776
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      Ibn Aziz
      Participant

      Heitor Galvao is right i endorsed his views.

    • #18794
      Ajay Vyas
      Participant

      Abdullah Baig
      May I know which type of work you are doing on RoF link. Can be share it

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