Sine: Weird Harmonic in FFT

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jasonkee111

Joined Mar 7, 2009
4
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).
 

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