[TenTec] DSP in CW transmit?

[Lee Crocker]

But it's not just the generation of the waveform that
is occurring in the DSP, it's also the time it takes
when you go from transmit to receive for the received
signal to get through the DSP filter and into your
ears.  This takes time, and is occuring during the
time you would normally be listening for the
"break-in" in the QSK cycle.  Just about the time a
breakin from the station you are working would occur,
the audio is switched, you're back in transmit, and
the side tone is now being routed to your ear.

So the time that used to be devoted to listening for a
break is now being used to process the received
breakin signal and just as it is about to get to your
ears, it then gets lost as the rig goes to transmit,
and the next character is generated and transmitted. 
During this period of transmission the recieve
processing is halted and its not until the received
breakin signal starts into the DSP again that
processing begins anew.  

Hence my original question, how much QSK is really
necessary?  Is it enough that you can be broken during
during the 7 dit-length word space?  Do you need to
have keyers that extend the word-space period?  I
think it is unlikely a rig that is busy doing all this
signal processing is going to ever be as good a QSK
radio as my old 580 delta in therms of "breakin". 
Maybe if there were separate receive and transmit DSP,
maybe if you had parallel co-processed transmitter and
receiver so thing were not being done serially, you
could approximate the behavior of the 580 delta. 

You may call these "bells and whistles" but it is
merely an engineering design trade-off between
mutually exclusive criteria.  You can't receive
processed audio until processing is completed, and if
the rate of data transmission is faster this
processing can occur in a given system, you won't be
hearing any breaks.  Like I said I used to judge a
radio by its QSK behavior.  But then I found QSK to
not be as totally useful as I once thought.  Really
fast well executed semi-breakin does just as well in
my opinion.

73  W9OY 


		
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