> VK6VZ:
> I recently listened to my friend's SDR-1000 alongside an FT1000MP and to
my
> shock (and disbelief!) on CW, found myself preferring the SDR-1000. The
> 25 - 50Hz filtering didn't ring to my ears on 15 to 20wpm CW - as others
on
> this reflector have also experienced. I believe the evidence of my ears,
> as this is all that really matter when I operate... Guess the performance
> of the SDR-1000 filtering is one of those things you have to hear to
believe.
>
It would be interesting to know what the actual shape of this filter is.
As Tom said, it is physically impossible for a "brick wall" filter of this
bandwidth to avoid ringing. If the shape factor is large, however, there
could be enough sideband energy allowed through the skirts, to give some
kind of inter symbol transition.
I am by no means a CW expert, having had a long period of mainly SSB
operation (before my current interest in Topband). Maybe it's just lack of
long term practice, but I find that my ears need a reasonably sharp
transition between symbols, or my copy suffers quite badly. Even in heavy
QRN, my filter bandwidth is never less than 300 Hz. I only drop it to 100
Hz (homebrew DSP) if there is actual QRM. In the parts of the world where I
have operated on Topband (ZS and ZL) QRN is almost exclusively the limiting
factor.
My two penneth.
73, Greg ZL3IX
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