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From: gd@milkfs.istc.sri.com.uucp (Greg DesBrisay)
Newsgroups: comp.dsp
Subject: Re: What's a waterfall display?
Message-ID: <28435@sparkyfs.istc.sri.com>
Date: 17 Oct 89 18:25:27 GMT
References: <1989Oct16.213117.20589@polyslo.CalPoly.EDU>
Sender: news@sparkyfs.istc.sri.com
Reply-To: gd@milkfs.istc.sri.com.UUCP (Greg DesBrisay)
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Organization: SRI International, Menlo Park CA
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A waterfall display of FFTs draws every new FFT curve on the screen
slightly below and "in front" of the last curve.  The effect is that
you get a 3-dimensional looking display with frequency as the x axis,
amplitude as the y axis, and time as the z axis.  The third axis
provides an very effective way to display time-varying signals.  For
example, Ray Vincent, formerly of SRI, who now works as an independent
consultant and professor at the Naval Post Graduate School uses a
system with a waterfall display to locate and identify all sorts of
radiated electrical noise.  Each different type of noise source has
it's own distinct three-dimensional pattern on a waterfall display.  

Greg