[linux-audio-user] how to synthesize this sound

Hi

I can't figure out how to do this classic sound that's heard on this
file http://www.atte.dk/download/sound.ogg. The one I'm talking about is
the rising sound in the background. I guess it's modulated with a square
lfo, but I can't figure out what's filter and what's pitch. If someone
did this sound a zillion times an could explain the idea, I'd really
appreciate it.

BTW: My main weapon is om...

-- 
peace, love & harmony
Atte
http://www.atte.dk