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Java FFT Analyzer


This applet is a powerful signal analyze toolkit. It turn you computer into a waveform generator and a spectrum analyzer. It can read from a WAV file. The Spectrum, relation, histograms, waterfall, transfer function and digital filter are integrated into this applet. You can also download a local version of this applet, which can run in windows 95/98 or windows NT.
If you can't see a RUN button and a STOP button below, you browser do not support JAVA applet, or you closed the support to JAVA applet in security setting of your browser. Use a browser that support JAVA applet, such as IE3.0, or open the security switch.
Press RUN below to start this applet and to see how strong it is.


For the security of browser, a JAVA applet can't access local resources of you computer, So it can't read or write files in your computer. This is very inconvenient for designer and user in some occasion. To add a JAVA applete the ability of access local resources, we design a little program, Localman, to work with this applet. Download Localman and run it in your computer, then the applet can access the local resources via Localman. Otherwise the applet can only used as a demo.
I had tested that IE3.0 support Localman, but Netscape 4.0 do not support it. To check whether  your browser support Localman is very simple: Run Localman first, then open SAT switch in the applet. If it show success, you browser support Localman, otherwise your browser do't support it.


Help Message
1.Toolbar

a)Open a data file of WAV, TXT, or DAT. (This function need support of Local man.)
b)Save signal to a WAV, TXT or DAT file. (This function need support of Local man.)
c)Curve cursor: This function is used to show the value of a special point in the curve. Move mouse to the point you want to know.
d)Peak List: This function is used to list the peaks in curve. Move mouse to the point you want to know, then click mouse to select it. You can select many points at one time, then press "show" button to see the values of them.
e) To Clipboard(BMP): This function copy the analyze result to clipboard.
f) To BMP File: This function save the analyze result to a Bitmap file.(This function need support of Local man.)
g) To Word: This function insert the analyze result to Word. Before use this function, You should run Word first, and open a new file, then go back to this applet. (This function need support of Local man.)
h) To Printer: This function copy the analyze result to a printer.(This function need support of Local man.)
i) To Editbox: This function copy the analyze result to editbox in applet, Press "show" button to see.
j) To TXT File: This function save the analyze result to a TXT file. (This function need support of Local man.)
k) To Excel: This function insert the analyze result to Excel. Before use this function, You should run Excel first, and open a new sheet, then go back to this applet. (This function need support of Local man.)
l) Help: Show help message. (This file.)
m) Demo: Show the main functions of the applet. This will take about two minutes.
n) Home: Show the WWW address of designer.
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2 Level Scroll
The level scroll is used to move the signal in display window.
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3 Vertical Scroll
The vertical scroll is used to zoom in tht signal wave.
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4.SAT Switch
This button is used to open or close the local resources accessing switch. If you chose open, a echo client function is  active, it transmit the related requests of applet to Localman(echo server) to access local resources.
Caution: Localman must run first, otherwise the applet should be blocked.
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5.Show Button
This button is used to open editbox to see data transfer to it.
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4. Menus
(1) Signal
a) Read File (This function need support of Local man.)
This function read signal from a WAV, TXT or DAT data file format. The DAT data file format is defined as:
"ILFI"            /*File Mark                  4 char     */
Nch               /*Channel number         1 int      */
Mlen              /*data length                 1 long int */
dt                   /*sample interval           1 float    */
v[1]                /*CH 1 scale factor       1 float    */
:
v[Nch]           /* CH N scale factor     1 float    */
x[1][1]           /*data 1 of CH 1           1 int      */
:
x[N][1]          /*data 1 of CH N           1 int      */
x[1][2]           /*data 2 of CH 1            1 int      */
:
x[N][2]           /*data 2 of CH N           1 int      */
:
x[1][M]           /*data M of CH 1          1 int      */
:
x[N][M]           /*data M of CH N         1 int      */.
b)Save  (This function need support of Local man.)
This function save signal to a WAV, TXT or DAT file.
c) Signal Generate
This function is used to produce a stimulate signal source of white noise,sine, and so on.
d) A/D(Sound Card) (This function need support of Local man.)
This function is used to record a signal from a sound card.
e)Exit
This function close applet window and return to browser.
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(2)Wave
a) Wave of CH1: This function display waveform of CH1.
b) Wave of CH2: This function display waveform of CH2.
c) Wave of CH1&CH2: This function display waveform of CH1 and CH2.
d) Shaft Centerline Orbit
This function display a shaft centerline orbit composed by CH1 and CH2. CH1 is X direction signal and CH2 is the Y direction signal.
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(3)Time
a) Auto Correlation
This function display the auto correlation signal of CH1 or CH2.
b) Cross Correlation
This function display the cross correlation signal of CH1 and CH2.
c) Power Cepstrum
This function display the power cepstrum signal of CH1 or CH2.
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(4)Spectrum
a) Power Spectrum
This function display the power spectrum of CH1 or CH2.
b) Amplitude-Phase Spectrum
This function display the Amplitude-Phase Spectrum of CH2 or CH2.
c) Real-Imaginary Spectrum
This function display the Real-Imaginary Spectrum of CH1 or CH2.
d) Transer Function
This function display the transer function of CH1 or CH2. That CH1 is input signal and CH2 is output signal.
e) Coherent Function
This function display the coherent function of CH1 or CH2. That CH1 is input signal and CH2 is output signal.
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(5)Array
This function display the spectrum array(Waterfall) of CH1 or CH2.
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(6) ZOOM
This function use ZOOM FFT technique to display a zoom spectrum.
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(7) Histogram
This function display the histogram of CH1 or CH2.
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(8) Filtering
a) Filter Design
This function is used to design a internal digital filter.
c) Signal filtering
This function use the internal digital filter to filter the signal of CH1 or CH2.
d) Signal Enveloping
This function use the internal digital filter to extract the envelop signal of CH1 or CH2.
e) DC Remove
This function is used to remove the DC part in  CH1 or CH2.
f) Resample
This function is used to resample all channel signal.

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