?? fftdll.htm
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<b><font face="Times New Roman,Times"><font color="#FF0000"><font size=-1><a href="http://drhe.tripod.com" target="_top">美國站首頁</a><a href="http://drhe.topcool.net" target="_top">北京站首頁</a></font></font></font></b>
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<center><b><font face="Times New Roman,Times"><font color="#CC0000"><font size=+2>FFT
DLL</font></font></font></b>
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<font face="Times New Roman,Times">FFT DLL 是我們設計的一個免費的 32 動態鏈接庫，它提供了最基本的Fourier變換功能，配合本站提供的</font>
<br><font face="Times New Roman,Times">Sound Daq, Jpeg Api動態鏈接庫，你可以很容易設計一個簡單的基于聲卡的譜分析程序。</font>
<br><font face="Times New Roman,Times"><font color="#000000">Press here
to <a href="fft.zip">download</a>.</font></font>
<br>
<hr WIDTH="100%">
<br><b><font face="Times New Roman,Times"><font color="#CC0000">FFT DLL
package include four file:</font></font></b>
<br><b><font face="Times New Roman,Times"><font color="#3333FF">1.fftdll.h</font></font></b>
<br><b><font face="Times New Roman,Times"><font color="#3333FF">2.fftdll.lib</font></font></b>
<br><b><font face="Times New Roman,Times"><font color="#3333FF">3.fftdll.dll</font></font></b>
<br><b><font face="Times New Roman,Times"><font color="#3333FF">4.fftdll.htm
(Help file)</font></font></b>
<br><b><font face="Times New Roman,Times"><font color="#3333FF">5.testfft.zip
(VC++ Example program)</font></font></b>
<br><font face="Times New Roman,Times"><font color="#CC0000">.</font></font>
<br><b><font face="Times New Roman,Times"><font color="#CC0000">Functions
in FFT DLL:</font></font></b>
<br><b><font face="Times New Roman,Times"><font color="#3333FF">1. void
fft(short sw,short n,float *x,float *y)</font></font></b>
<br><font face="Times New Roman,Times"><font color="#000000">sw=0 FFT ,
sw=1 IFFT</font></font>
<br><font face="Times New Roman,Times"><font color="#000000">n=256/512/1024/2048/4096</font></font>
<br><font face="Times New Roman,Times"><font color="#000000">x: Array of
data</font></font>
<br><font face="Times New Roman,Times"><font color="#000000">y: Array of
data</font></font>
<br><font face="Times New Roman,Times"><font color="#000000">.</font></font>
<br><b><font face="Times New Roman,Times"><font color="#3333FF">2.void
spectrum_r_i(float *wave,float *re,float *im)</font></font></b>
<br><font face="Times New Roman,Times"><font color="#000000">wave: raw
data of signal, 1024 sample point</font></font>
<br><font face="Times New Roman,Times"><font color="#000000">re: real part
of spectrum</font></font>
<br><font face="Times New Roman,Times"><font color="#000000">im:imaginary
part of sprectrum</font></font>
<p><b><font face="Times New Roman,Times"><font color="#3333FF">3.void spectrum_a_p(float
*wave,float *a,float *p)</font></font></b>
<br><font face="Times New Roman,Times"><font color="#000000">wave: raw
data of signal, 1024 sample point</font></font>
<br><font face="Times New Roman,Times"><font color="#000000">a: amplitude
of spectrum</font></font>
<br><font face="Times New Roman,Times"><font color="#000000">p: phase of
sprectrum</font></font>
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<blockquote>
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<td><b><font color="#990000">Example of VC++:</font></b>
<br><img SRC="fft.gif" height=351 width=549>
<br>
<hr WIDTH="100%">
<center>1999.12.20</center>
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