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: [EMAIL PROTECTED]
To: elecraft@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".
************** Snip **************
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