waterfall not doing as I expect.

PlotLab

Thread Starter: Andre C Started: 2/28/2007 9:19 PM UTC

Replies: 1

2/28/2007 9:19 PM UTC

waterfall not doing as I expect.

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Andre C

I do not think I am using the waterfall component properly in c++5.

I am working on a program which takes the line-in of the soundcard sas
the sound source (a shortwave radio.)

I want a waterfall scope to show the sound form, this is useful to
identify types of transmissions such as morse code where a pure tone
is sent. I therefore want the water fall to show hte pure tone. MixW
is a good example of this.

So I have dropped a audioin and audiotoread component on the form. But
when I get audio into the form the waterfall generates a green screen
with specules of blue tones. Even when I can clearly here a morse code
I see no obviouos line. What I do note is that when atone is received
the blue specules increase but across the entire screen.

My soundcard in on-board. Running XP pro on Athlon 2600. the waterfall
component is presently with default settings.

Any thoughts. I am quite noob at c++.

Andre

5/27/2007 12:34 AM UTC

Re: waterfall not doing as I expect.

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jimmy cortes

Actually I have the same issue. I think it doesnt calculate the Short time fourier trasform (Short FFT). I have used Mathlab waterfall and that does what I have expected. I used a sine signal generator to produce an almost pure harmonic, so that way, I could see just a line for all time, but it doesnt happended. It prints a lot of lines and colors like a rainbow. Try first calculating the FFT and then use the waterfall. I can not try this because I have another installation issue. I have published the same question at signalab.net forum.

Good look,

jimmy