User's Manual

WiNRADiO G39DDC User’s Guide
36
exact carrier frequency will result in a whistle being heard, its pitch being
directly proportional to the IF shift displacement. This is because while you
have changed the tuned frequency, you have not changed the “BFO” (or rather
the digital equivalent of it) simultaneously.
To make it possible to move the filter but still remain tuned to the same
frequency, there is also an associated Passband tuning function: This is
invoked simply by dragging the filter passband with the right mouse button
instead of the left one. This makes it possible to finely adjust the filter position
in the AMS, LSB, USB, ISB, DSB and CW modes without the whistle effect,
because the internal “digital BFO” will be tuned alongside the passband
movement.
When the demodulator passband is being dragged using the right mouse
button, a red PBT indicator will appear next to the cursor to indicate you are in
the PBT mode, and showing the tuning offset at the same time:
To revert to the IF shift mode, simply use the left mouse button again.
Frequency Stepping
To make the chapter on tuning complete, we need to fast forward a bit: There
is one more tuning facility located on the right under the Tuning tab (all the
function tabs will be described in more detail in one of the following
chapters):