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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