[Elecraft] DSP Unit and PSK31 and other digital modes

[Robert McGwier]

It would be inappropriate to use the LMS noise canceling in the
DSP option on PSK31.  I don't have mine yet so I can't tell you if it will
dial in narrower filters that are straight bandpass (not adaptive)
filters, but the KDSP2 page seems to imply this.  Unfortunately,
the KDSP2 pdf file for the manual is no longer available for
download on that page.  If you can dial in a narrowband FIR filter
(bandpass) with the DSP unit, this will not likely hurt PSK31 and will
likely
help so long as you do not get it too narrow.  200 Hz given what
I think would be likely filter lengths is the narrowest setting
I would use on PSK31.  The issue with using narrow audio filters
is the AGC level before the audio filter sets the level of the
signal following the filter unless this is compensated for in
the DSP audio filter.  You would see this is a strong signal inside
your IF bandwidth, set by the K2 IF filters, resulting in a
pumping of the level of the signal coming out of the KDSP2 audio
filter.

73's
Bob
N4HY