[P3] Waterfall Display

[ke7vwi]

I have never used a waterfall display before getting my P3 (sn 155). I used
 spectrum analyzers before.
Does anyone have a recommendation on an article or some info on  
using/interpreting the waterfall display?
In the commercial world, never used them just spectrum analyzers.
Oh the P3 works well. There are more signals than I thought out there. Even
 the ones in the noise.
Thanks
73
Jim H
KE7VWI
K3 2828 P3 155
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[Bill W4ZV]

ke7vwi wrote

Does anyone have a recommendation on an article or some info on  
using/interpreting the waterfall display?

I searched but the following is the best I could find (which isn't great):

http://en.wikipedia.org/wiki/Spectrogram

A waterfall is basically a spectrum (signal amplitude versus frequency) but with the added dimension of time (amplitude versus frequency versus time).  A waterfall is most useful for detecting signals that are not continuously present.  For example a weak DX station only sending short bursts when he's answering callers that may be calling split on a different frequency.  Or for extremely weak signals fading in and out of noise (e.g. QSB on the low bands or meteor scatter at VHF).  For weak signals buried in noise, your eye would probably never detect these in a spectrum display but they become quite apparent in a waterfall display.  Once you know exactly where a weak signal is, then you can tune your receiver to the exact frequency and begin to apply filtering in both the radio and your ear/brain to copy it.

I use waterfalls mainly for weak signal CW on the low bands.  They're especially helpful for signals at or below the noise floor.  I understand they also work well for digital (not my thing except for the original digital mode---CW).  They don't work as well for wideband and time-varying signals like SSB.  If you seldom operate CW or digital modes, I doubt you would find a waterfall very useful.  

I prefer a waterfall only mode for my applications and will probably use that when Alan eventually makes it available on the P3.  As the P3 stands now, I maximize the waterfall portion of the display, turn MKR on in the spectrum area only, center it over a waterfall signal just below and press QSY to identify the station by ear.  

CW Skimmer is another alternative that uses waterfalls exclusively.  Below are some screen shots of Skimmer's waterfalls (which are unique in their ability to show CW dots and dashes over a wide dynamic range of signal strengths):

http://dxatlas.com/CwSkimmer/

I hope this helps but the best thing is to simply play a game with the waterfall display.  Try setting Ref Lvl just at the noise floor and see if you can copy the weakest signals the waterfall detects.  When you can, you'll be ready to work weak CW DX on the low bands or at VHF.

73,  Bill