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LF: glfer 0.3.1 and non-linear signal processing

To: [email protected]
Subject: LF: glfer 0.3.1 and non-linear signal processing
From: "Claudio Girardi" <[email protected]>
Date: Wed, 16 Oct 2002 08:23:30 +0100
Reply-to: [email protected]
Sender: <[email protected]>
Dear LF Group,
since I was curious to see the effect of the non-linear processing trick described by Alex and of limiting the input signal, I implemented them in glfer and released version 0.3.1; as usual you can find the sources at http://www.qsl.net/in3otd/glfer.html .

The FFT routine has now a selectable non-linear processing option, according to the formula given by Alex and also a selectable "Hendrixizer", which uses the 10th radix of the normalized input signal as a limiting function.

I did some quick test yesterday evening, but there were no QRSS signals (hi) so I used some weak CW signals on the 20 m band; as noted by Jim, the two non-linear processing options are in some way related, since the spectra they produce are somewhat similar, but certainly more testing with real LF signals is needed...

As a last note, this release should correct also the dependencies on the fftw library, a bug which prevented compilation on systems without this library installed...

Happy experimenting with non-linear processing!

                            73 de Claudio, IN3OTD

--
Home Page: http://www.qsl.net/in3otd/

Alex wrote:
[snip]
So it is very simple to realize! The only addition is input convertion
of the incoming signal

S1(t) = S(t)/[A + S(t)*S(t)]

where S(t) if signal from RX. Parameter A shold be controlled to get
best reciption. Than signal S1(t) is processed by conventional procedure
(say FFT).

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



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