Sine: Weird Harmonic in FFT

Discussion in 'Programmer's Corner' started by jasonkee111, Dec 7, 2009.

  1. jasonkee111

    Thread Starter New Member

    Mar 7, 2009
    4
    0
    Hi. I have a set of data of 22k sine wave feed it to fft. The result is
    very smooth as shown in attachment fft magnitude. However, when i do the
    0.5sin22k, it results of a lot of harmonic in attachment fft_0.5sin22k.

    May i know the reason causing this?


    FYI, the set of data of sin22k is in integer form.

    When i do the 0.5sin22k, i only take the integer output by truncating the fraction. i did some zero padding. It is due to my sin generator can generate 24 bit output. In order to multiply with a fraction(precision
    0.001), i add another 10 bit (zero padding).
     
  2. jasonkee111

    Thread Starter New Member

    Mar 7, 2009
    4
    0
    sorry. I have found out the problem. There is something wrong with my raw data.

    Thanks
     
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