>On going very interesting discussion: RF/IF vs audio.
>
> > Well, I think you guys are both right.
> >
> > The DSP operates ahead of the audio stage, and thus can
> > be called IF.
> >
> > Of course, the frequency of 14 khz is certainly in the
> > audio range.
>
>Well, do you understand the difference between these two
>words: acoustic and electromagnetic?? If one signal
>is acoustic and the other electromagnetic, do we think
>of them being "the same"..........no, of course not.
The semester's winding down, and I have
a little time, so I think I'll jump in here.
How is this for a distinction between "RF"
and "AF"? A signal is considered to be
RF if it must be downconverted in order to
detect the intelligence it carries. An RF
signal is almost always destined to be fed
into an upconverter (mixer), a downconverter
(mixer or detector), or an antenna. An AF
(or baseband) signal, on the other hand is
destined to drive a speaker, a pair of
headphones, or some other type of
transducer. By this definition, an "IF"
signal is considered to be a special case
of RF.
>An audio signal is always referenced to DC; just as is
>a video signal, as in television...
>However, the intelligence in an IF 14 kHz signal is all
>centered about the 14 kHz "carrier". And to access that
>intelligence, it must be converted to "baseband"...see
>a previous post on that topic.
I would suggest that a "baseband" signal is
one that requires no further downconversion
in order to extract the intelligence it carries.
I should go to bed...
73 es gn,
Dave NB4J
--
David F. Kelley, Ph.D.
Assistant Professor
Electrical Engineering Dept.
Bucknell University
Lewisburg, PA 17837
(570) 577-1313
dkelley@bucknell.edu
|