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Do not understand the BB11BPMDSpreadFIR4SSE in dot11b and the TQuickPulseShaper in dot11b brick。 RRS feed

  • Question

  •       Hi, I have read the code of dot11b in previous versions and brick model。However,I do not know the FIR function。

         In previous versions,for instance the code in  bbb_tx.c which was located in  src\bb\dot11b,    in funtion BB11BPMDPacketGenSignal, after BB11BPMDPacketTx4X, the sample had been 4x upsampling with zero-padding.I really do not understand the function BB11BPMDSpreadFIR4SSE,could you tell me the detailed information about  function BB11BPMDSpreadFIR4SSE ,I do not know the instructions of SSE.  By the way,11b uses 4x upsampling with 44MHz Sampling Rate,and does it has some relationship with the 802.11b chip rate 11Mc/s ?

         Hope to reply,thank you.

    Thursday, February 13, 2014 2:03 AM

All replies

  • Hi d kd,

    Yes, BB11BPMDPacketTx4X upsamples (zero-padding) the frame.

    Then BB11BPMDSpreadFIR4SSE processes the frame by a raised cosine filter, to shape the final basedband signals proper for TX.

    We recommend you refer the TQuickPulseShaper brick implementation for the same idea, which has better modular code. Both implementation uses SSE instructions to optimize the processing speed. You can refer Vector1 library (vector128.h) for the SSE wrapper types and functions.

    Thanks, -Qi

    Friday, February 14, 2014 5:18 AM
    Answerer
  • Thank you. I will look for some more information. 
    Monday, February 17, 2014 8:28 AM