Linrad-02.41

[Leif Asbrink <sm5bsz.com; leif@xxxxxxxxxxxxxxxx>]

Hello All,

Today I uploaded Linrad-02.41 at these three places:

http://www.sm5bsz.com/linuxdsp/linroot.htm
http://g7rau.demon.co.uk/sm5bsz/linuxdsp/linroot.htm
http://nitehawk.com/sm5bsz/linuxdsp/linroot.htm

The automatic spur removal is now significantly better.
It should no longer remove CW signals - but of course
the algorithms need some fine tuning so I am interested 
in feedback with recordings where it does not work well.

The AM mode has a new feature. When coh2 is selected, 
the coherent detect I signal goes to one ear while the Q
signal goes to the other. This is as it has always been.
For an AM station this means that the AM modulation
goes to one ear and the FM modulation to the other.

Strong AM stations tend to have weak FM modulation so the
FM channel is often very low in volume. The new feature 
is that there are now independent AGC functions for the 
AM and the FM audio channel (derived from the audio signals)
and therefore both ears have similar soundlevels.

The FM signal with typically 10 dB more gain allows copying
of weak stations that have the same frequency as a stronger 
one.

There are also many bug corrections in linrad-02.41.

            ---------------------------------------

There is a DSP challenge at these locations:
http://www.sm5bsz.com/linuxdsp/spur/autospur.htm
http://g7rau.demon.co.uk/sm5bsz/spur/autospur.htm
http://nitehawk.com/sm5bsz/spur/autospur.htm

There is a file 20mnoise1.wav (13 megabytes) that was recorded
by W3SZ on 20 meters. The file has some QRN and a relatively
weak CW signal that is only about 2 kHz away from 40 dB
stronger CW signals.

Many SDR programs can use .wav files for input. I would be
curious to know how sucessful different programs are in 
making this signal visible in the waterfall and how well 
the loudspeaker output can be copied. 

The challenge is on the automatic spur rempoval page
because the 20mnoise1 file has many spurs.

I would appreciate if many of you could make some extra
testing on Linrad-02.41. The latest stable is now 02.35
and that is pretty old now. The bugs I introduced with
the structural changes I had to do to get started with 
the Tx side have made 02.36 to 02.40 somewhat unstable
(more than usual) but I hope to get the bug reports that
will allow me to make 02-41 or perhaps 02-42 the latest
stable version.


  73

  Leif / SM5BSZ


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