FW:RE: linrad, spectran,dspfil (Leif Åsbrink Sept 29 2002)

[Leif Åsbrink <leif.asbrink@xxxxxxxxxxxxxxxxxxxx]

-----Original Message-----
From: owner-linrad@xxxxxxxxxxxxxxxxxxxxx
[mailto:owner-linrad@xxxxxxxxxxxxxxxxxxxxx]On Behalf Of Leif Åsbrink
Sent: Sunday, September 29, 2002 4:22 PM
To: linrad@xxxxxxxxxxxxxxxxxxxxx
Subject: RE: [linrad] linrad, spectran,dspfil


Hi Arie,

 
> I am still looking for a dsp programme which makes deciphering of morse
> signals buried in the noise better than the SP in my head does it.
> 
> In fact I have not been too succesful.
> 
> The windows programmes spectran ( i2PHD) and dspfil(JE3HHT) do a fair job
> but not better than my ears and the adaptive filter in my brain..
> And than there is Linrad. I must confess that I have not yet succeeded in
> getting Linrad working better than the dos programmes. It anyhow is rather
> cumbersome to set up.
 
Sure. Linrad is not designed for any particular purpose so it is up to 
the user to define the processing that will suit his task. Learning
how to get the most out of Linrad will take quite some time;-)

Can you make a one minute recording of some real signals that are
just at the limit where you can copy by ear - but not completely. 
I would process them with Linrad and send the result back.

Note that the ability of Linrad to improve depends on the signal itself. 
A signal that is random phase modulated at a speed not much slower than
the keying speed can not be improved at all. The same is valid for signals
that have severe chirp. Signals that drift with a drift speed that does not
change very fast can be improved quite a bit. The same is valid for signals 
that are phase stable.

"Quite a bit" means 2 to 4 dB;-)

I have a feeling you did a recording quite some time ago, but I do not remember
what the outcome was. I have a great interest in this because if you are able
to copy equally well without dsp I am curious to know how you do it. 
Most operators do not have this ability in my experience. I am refering to 
signals that allow a bandwidth of less than 20Hz. If chirp, random phase 
modulation or keying speed make the bandwidth much greater, then ear and 
brain can do completely without computer support.

  73

 Leif  /  SM5BSZ




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