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Sine Waveform:Weird Harmonic in FFT

 
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jasonkee111
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PostPosted: Mon Dec 07, 2009 1:57 pm    Post subject: Sine Waveform:Weird Harmonic in FFT Reply with quote
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).

thanks
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jasonkee111
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PostPosted: Mon Dec 07, 2009 3:50 pm    Post subject: Reply with quote
sorry. I have found out the problem. There is something wrong with my raw data.

Thanks
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