--- In softrock40@..., Bill Tracey <kd5tfd@a...> wrote:
...the gunk you see near the center frequency with or w/o hardware
attached is an artifact of the signal processing architecture, and
noise
near DC on the audio input (ie 60 hz hum,. etc)...
Exactly, and this is one tough sucker to get rid of.
The soundcard is one of the most vulnerable spots for letting in
spurious signals. Most soundards get around the problem by rolling off
the frequency response below 100Hz or so.
Rolling off is not the same as eliminating, however, and when you can
mix the residual spurious signals up into the center of the passband,
they're conspicuous weak signals just like anything else would be.
It is possible through DSP magic to subtract out the gunk, but you pay
for it with a higher MDS. Preferable on the whole to use a better
soundcard.
73
Frank
AB2KT
