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Date: Tue, 15 Oct 2002 22:40:11 +0000 (GMT)
From: "Alexander S. Yurkov" <fitec@omskcity.com>
To: rsgb_lf_group@blacksheep.org
In-reply-to: <5.1.0.14.0.20021015135147.00a8df98@gemini.herts.ac.uk>
Message-ID: <Pine.LNX.3.95.1021015222630.264A-100000@fitec.omskcity.com>
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Subject: Re: LF: Re: Non-linear signal processing
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Dear Jim.

Thanks a lot for coment.

On Tue, 15 Oct 2002, James Moritz wrote:

> As was seen some time ago with the experimental "Hendrixizer" clipping 
> feature added to Jason, non-linear processing of the signal can certainly 
> be an improvement under some conditions. The conditions seem to be that the 
> noise within the receiver passband is wide band in nature; if strong 
> narrow-band signals are also present, intermodulation and/or blocking 
> effects occur. Due to the non-linear term in Alex's function above, I 
> expect the same would apply. 

Certenly if sinusoidal QRM is present nonlinear processing should give
bad resiption due to blocking and intermodulation. Prefiltering passband
should be as wide as posible but all sinusoidal QRM should be rejected.
So some art is needed to tune RX passband and A parameter to get best
reciption. May be it is bad for professional porpose but it is wonderfull
for HAMing...


May be it is better to use function A*S(t)/[A + S(t)^2] to avoid variation
of linear part of function when A is changed. 

> Well, now all I have to do is sit back and relax while the spectrogram 
> software guys get it working... :-)

I hope it will be soon because it is not very complex if original programm
text is present.


73 de RA9MB/Alex
http://www.qsl.net/ra9mb