[Elecraft] DSP and CW?

[sheajohnw at aol.com]

I operate mostly digital mode and use MixW to help decode contest CW 
QSOs.  Before I acquired the DSP2, I could adequately decode by machine 
only strong perfectly sent CW signals such as W1AW code practice 
transmissions using either my K2/100 or IC-735.  After installation of 
the DSP2 NR, I noticed a great reduction in background hash improving 
the CW S/S+N ratio.  The DSP2 made it possible for me to machine decode 
most contest CW QSOs.  The DSP2 NR does alter the CW tone quality to a 
certain extent, but makes listening easier due to the reduction in 
background noise.  Less aggressive settings improves tone quality, but 
also reduces background noise reduction.  I do not like the DSP2 NR for 
SSB because of the watery quality it gives to voice.  Reducing NR 
aggressiveness improves voice quality, but at the expense of background 
noise reduction.  Very weak CW DX signals cannot be decoded by my 
machine, even with the NR on, but such signals are often clear enough 
to be decoded by ear with the NR set on.  The NR does not help me much 
at very narrow audio filter settings, but seem to work well with wider 
settings.   The audio filters of the DSP2 are excellant and do not 
slightly shift frequency between TX and RX like the K2 crystal filters. 
  The slight frequency shift using XFil is only an issue for me when 
machine decoding.  I usually operate CW with the AGC set off and the NR 
on controlling volume using RF gain.  Turning the AGC off is very 
important for weak signal machine CW decoding.  It appears to me that 
machine decoding of machine generated CW is improved when the 
background noise between dits and dahs has been well supressed with 
enough audio tone being present to activate the CW decoder.  Hand sent 
code can be hard to decode by machine as it has less than perfect 
timing of dits, dahs, and spaces.  The computer is no replacement for 
the trained human ear when it comes to copying CW.  While weak hand 
sent DX CW may not be very copiable by machine, the DSP2 NR should help 
one manually copy weak hard to copy signals.  I think that the DSP2 is 
a great asset but one should not expect weak signal miracles such as 
being able to hear and copy DX transmissions that are imperceptable 
with the NR off.  The K2 DSP2 is the only DSP unit that I have used so 
I cannot compare it to other rigs and units.

-----Original Message-----
From: cak at dimebank.com
To: elecraft at mailman.qth.net
Sent: Thu, 29 Mar 2007 10:24 AM
Subject: [Elecraft] DSP and CW?

Does this combination make sense? I operate 100% CW. These days, I seem
to be chasing a lot of very weak signals with questionable readability.
My vertical isn't the quietest of antennas (they never are) and my
neighborhood has a fair amount of QRM on 40m during "real people hours".

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