[Elecraft] P3

[Doug Joyce]

It reproduced ok on my download copy.

73,  Doug  VE3MV

----- Original Message ----- 
From: "Philippe Trottet" <TROTTET at unhcr.org>
To: "Kok Chen" <chen at mac.com>; "Elecraft Reflector" 
<Elecraft at mailman.qth.net>; "turnbull" <turnbull at net1.ie>
Sent: Tuesday, February 16, 2010 6:10 AM
Subject: Re: [Elecraft] P3


>P 130 is blank on the pdf document !
> 73's
> Philippe A65BI
>
>>>> Kok Chen <chen at mac.com> 16-02-2010 14:16 >>>
>
> On Feb 16, 2010, at 12:39 AM, turnbull wrote:
>
>> When you write the manual for the P3 would you please include a good 
>> explanation of the use of waterfall displays.  I have one on my OII but 
>> do not fully understand its benefits.
>
> Spectrograms, such as "waterfalls," make use of your eye-brain system to 
> help find signals that are below the noise level, especially when signals 
> are drifting and don't allow temporal averaging methods.
>
> You can see an example of its use (1971) here:
>
> http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730010095_1973010095.pdf
>
> Fig 11-7 on page 130 (although poorly reproduced in the PDF scan) and the 
> text on that page explains its use for discovering very, very weak and 
> very, very DX signals.
>
> In the amateur world, the first use of waterfalls was by Skip KH6TY in his 
> Digipan program, I believe.  Without Digipan and the ease of "waterfall 
> tuning," PSK31 probably would not have become as popular as it is today.
>
> With the addition of some special filtering, you can make a waterfall see 
> even deeper into the noise when the signal is not drifting. The two 
> figures here
>
> http://homepage.mac.com/chen/w7ay/cocoaModem/UsersManual/mfskManual/mfskManual/dominoex.html#weak
>
> show the same weak DominoEX signal with 18 FSK carriers.  The top figure 
> is what the weak signal looks like in a simple waterfall, and the figure 
> at the bottom, with the same input SNR, takes advantage of a signal that 
> is not drifting, as explained in the accompanying text.
>
> In the digital world, you can't work them unless you can *see* them :-).
>
> A good waterfall display will also show a CW signal that you can't hear, 
> and can make "zero beating" a virtually instantaneous effort.  Or zero 
> beating to a synchronous AM carrier, etc etc.
>
> 73
> Chen, W7AY
>
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