From: "jannsen" <0482183881-0001@t-online.de>
To: rsgb_lf_group@blacksheep.org
References: <5.1.0.14.0.20020726140304.00ae6518@gemini.herts.ac.uk> <17YCsw-1DnzvMC@fwd01.sul.t-online.com> <3D4257FC.CDC26C4D@usa.net>
Subject: LF: off topic/Jason
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Date: Sun, 28 Jul 2002 00:37:43 +0200
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Alberto di Bene schrieb:
> jannsen wrote:
>
> > Hi Jim, Alberto es all
> >
> > my report see attachment. conspicuous the spurii during the switchovers from
> > tone to tone. has Alberto an explanation ?
>
> Hello Uwe and the group,
>
>   yes, there is an explanation.
> The waterfall window has a strong visual AGC applied, so to put into greater
> evidence the tone received. The AGC gain is computed only taking into
> consideration what falls inside the two yellow lines.
>
> Now picture into your mind the FFT buffer as a long glass tube, where coloured
> water enters from one side, flows all along the tube and exits from the other
> side. The water can have different colours, which correspond to the frequency
> of the incoming signals. Suppose a single frequency is arriving,
>  corresponding to
> a red water colour. This is the predominant colour, your eye sees only it,
>  unconsciously
> discarding spurious strikes of other colours. Now the tone changes. While the
> red water still flows towards the exit end of the tube, from the other end
>  blue
> water is coming. Until the tube is full of only blue water, there will be a
>  changing
> mixture of both colours in the tube, red slowly decreasing and blue
>  increasing.
> In this condition, your eye is no more dominated by a single chromatic
>  sensation,
> and you see the red, the blue and the other strikes. This also explains the
> blurring that can be seen, lets' say, in Spectran when receiving a DFCW signal
> and the tone changes.
> In this analogy your eye is the equivalent of the FFT processing, which is
>  presented
> with the input buffer (the tube).
>
> It's not a perfect example, many things could be criticized, but I do hope it
>  can
> explain a little what's happening.
>
> 73  Alberto  I2PHD
>
Hi Alberto,

up to now I have`nt read such a nice vivid explanation in form of an 
"analogat" (new latin language of philosophers).

do you have a similar illustration naming it "Jason" ? I do know the 
Jason myth but can`t imagine any connection with your progr.

tks es regards

Uwe/dj8wx