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Thread: How to do FFT spectrogram plotting using QWT

  1. #1
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    Default How to do FFT spectrogram plotting using QWT

    Hi
    I am bit unaware of qwtspectrogram plot. I went through the example but its not of much help to me.
    I want to do spectrogram plotting of my FFT data.
    The details of my FFt computation is
    1) Window Size = 2048
    2) Sampling frequency = 10 Mhz
    I used FFTW for fft computation.
    My question is:
    1) how to map my complex buffer data to QWT rater data ?
    2) How to set frequency axis and time axis ?
    Looking forward for your help
    Last edited by shivendra46d; 1st June 2018 at 11:07.

  2. #2
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    Default Re: How to do FFT spectrogram plotting using QWT

    You have to have a QwtRasterData object that acts like a bridge between your data and the spectrogram.
    You can implement your own or copy the data into a buffer, that can be used by QwtMatrixRasterData.

    But when implementing your own data object be careful with what you do inside the YourRasterData::value - it gets called for every pixel.

    Uwe

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