FftLab Java Applet - Revisited

Hi all,

this is a short note that I've invested a few hours of my spare time
to improve and adapt Dave Hale's free FFT Laboratory Java applet. The
original is at his Stanford web site at
http://sepwww.stanford.edu/oldsep/hale/FftLab.html. I found this
applet to be highly instructional for explaining the Fourier transform
basics and therefore a valuable addtion to my dspdimension.com web
site. The new version is at
http://www.dspdimension.com/html/Lab/FftLab.html and offers many
improvements wrt. drawing behaviour as well as a new magnitude/phase
display.

It should work on any of today's Java compatible browsers, but since I
don't have a PC within reach I'd like to hear comments especially from
the PC people out there (and of course from the rest of you as well).
Comments, suggestions, bug reports, anything. If you'd rather wish to
email me instead of posting here please use the contact form on my web
site at http://www.dspdimension.com .

Have fun!
--smb

http://www.dspdimension.com/html/Lab/FftLab.html

Very nice tool!
Tested it with both Opera 7 and IE 6 on Windows XP. 
Is there any chance to run it local on my PC too?

Hans

Hi Hans,

thanks for checking it out. I'm not familiar with creating standalone
applications in Java but I'm sure there is a way - I think that's an
excellent idea!

Viele Gr��e,
--smb


Eder Hans wrote:
> http://www.dspdimension.com/html/Lab/FftLab.html
> 
> Very nice tool!
> Tested it with both Opera 7 and IE 6 on Windows XP. 
> Is there any chance to run it local on my PC too?
> 
> Hans

Eder Hans wrote:
> http://www.dspdimension.com/html/Lab/FftLab.html
> 
> Very nice tool!
> Tested it with both Opera 7 and IE 6 on Windows XP. 
> Is there any chance to run it local on my PC too?
> 
> Hans
> 
> 

Works with Netscape 4.6 and Mozilla 1.6 under Windows XP

Stephan M. Bernsee wrote:

> Hi all,
> 
> this is a short note that I've invested a few hours of my spare
> time to improve and adapt Dave Hale's free FFT Laboratory Java
> applet. The original is at his Stanford web site at
> http://sepwww.stanford.edu/oldsep/hale/FftLab.html. I found this
> applet to be highly instructional for explaining the Fourier
> transform basics and therefore a valuable addtion to my
> dspdimension.com web site. The new version is at
> http://www.dspdimension.com/html/Lab/FftLab.html and offers many
> improvements wrt. drawing behaviour as well as a new
> magnitude/phase display.
> 
> It should work on any of today's Java compatible browsers, but
> since I don't have a PC within reach I'd like to hear comments
> especially from the PC people out there (and of course from the
> rest of you as well). Comments, suggestions, bug reports,
> anything. If you'd rather wish to email me instead of posting here
> please use the contact form on my web site at
> http://www.dspdimension.com .
> 
> Have fun!
> --smb

Works fine here on Mozilla 1.7/Win2000.

It took some time until I happened to find out that curves can be 
modified using the mouse pointer.

I'd propose that you add a hint for newbies...

Bernhard 

Eder Hans wrote:


> Is there any chance to run it local on my PC too?

Not that difficult. I tried it out and it works fine here.

Run the applet once through the browser (this will have it download 
all necessary class files). You'll find them in the browser's 
cache.

You need the following files (names maybe modified by browser):

Fftlab.html
ComplexSamplesPanel.class
ControlPanel.class
Fft.class
FftLab.class
FftLabController.class
LabeledChoice.class
MainPanel.class
Samples.class
SamplesPanel.class
SamplesView.class

Copy these files to a directory, let's say /home/my/download/fftlab.

Another way: with a tool like 'wget' download them from within the 
newly created directory.

wget http://www.dspdimension.com/html/Lab/FFTlab.html
wget http://www.dspdimension.com/html/Lab/Java%20Classes/<filename>
with <filename> replaced by either of the above files.

Now you have to modify the file FFTlab.html:
replace the string "Java%20Classes" by a single "."

Then launch the local file FFTlab.html with your browser. 
Should work.

If you're familiar with your java console:
add the local directory to the classpath (or move the .class files 
there), and then run the application directly from the console:
java  FftLab

Works for me, too.

Bernhard

Hmm, I'm not sure what you mean... you can click and drag the mouse
within these "lollipop" displays to change the curves... is that what
you're referring to? That's the whole point about the applet. Do you
find that in any way unclear?

--smb

Bernhard Holzmayer <holzmayer.bernhard@deadspam.com> wrote in message news:
> 
> It took some time until I happened to find out that curves can be 
> modified using the mouse pointer.
> 
> I'd propose that you add a hint for newbies...
> 
> Bernhard

I believe some browsers can download content for offline browsing,
which should do all this for you without having to change the path
manually. I could also upload a ZIP file that contains all the
required files... that's probably the best solution for now.

--smb

I've included a downloadable offline version on that page.

--smb

These things are always clear to the person who has developed the 
program, and almost always unclear to the new user who may be far from 
sure what they are supposed to do, and why!

I suggest providing a few preset waveforms (bandlimited square/saw etc). 
freehand drawing is a somewhat haphazard procedure at the best of times 
(since you are in effect only drawing the top 20dB or so of the shape), 
and interpreting the results of it equally so. So the pedagogical 
question is, what should the novice draw, in order to observe something 
significant, to learn something? People who already know, may not need 
the applet in the first place. The ~really~ cool thing to add would be 
real-time synthesis of the waveform!

Richard Dobson



Stephan M. Bernsee wrote:
> Hmm, I'm not sure what you mean... you can click and drag the mouse
> within these "lollipop" displays to change the curves... is that what
> you're referring to? That's the whole point about the applet. Do you
> find that in any way unclear?
> 
> --smb
> 
> Bernhard Holzmayer <holzmayer.bernhard@deadspam.com> wrote in message news:
> 
>>It took some time until I happened to find out that curves can be 
>>modified using the mouse pointer.
>>
>>I'd propose that you add a hint for newbies...
>>
>>Bernhard