WiNRADiO G65DDC User’s Guide
54
Opening the User Memory File
When the WiNRADiO
Excalibur Sigma
receiver application starts up, the most
recently used memory file will be opened automatically.
To open a different memory file, select
Load user memory
from the
File
menu. A dialog box will pop up allowing you to choose a memory file to load.
Notch
The
Notch tab
contains controls dedicated to the
Notch filter
function. There
are two notch filters which can be operated simultaneously:
The notch filter is a
band-stop
filter which can be used to minimize the effects
of interference falling inside or near a received station’s spectrum. Each filter is
activated by pressing the associated
Enable
button. The center frequency and
the width can be adjusted using the appropriately named controls.
For both notch controls, the same usage rules apply as with the demodulator
bandwidth setting, i.e. the values can be changed by direct manual entry, or
selected from the drop-down list.
Another way of changing the notch filter parameters is by dragging the
stopband of the filter (a blue shaded area) with the mouse. The stopband
width can be adjusted by dragging the edges, while the center frequency can
be changed by dragging the center line, which makes it possible to
conveniently position the filter stopband over the interfering signal.
The
Center
button serves to relocate the notch filter stopband to the center of
the demodulator filter passband. This can be useful in situations when the
notch filter is hidden beyond the currently visible demodulator spectrum limits,
in particular when the spectrum is zoomed in, or when first enabled.
The following picture shows a signal with strong interference in the passband
