Yaesu FTDX10 Operation Manual page 46

The IF SHIFT and Variable IF WIDTH features together form a very effective interference-fighting fil-
tering system.
For example, in Figure "A", you can see how in-
terference has appeared both on the high and low
sides of the desired signal.
Rotate the [WIDTH] knob, the interference from one side
can be eliminated (Figure "B"). Next, rotate the [SHIFT]
knob to re-position the passband (Figure "C"), the inter-
ference on the opposite side can be removed, without
re-introducing the interference previously eliminated in
Figure "B".
For best interference reduction, the WIDTH and SHIFT features are the primary tools you should use. After nar-
rowing the bandwidth (WIDTH) and/or adjusting the center of the passband (SHIFT), the Contour control may
then yield additional signal-enhancement benefits on the net residual bandwidth. Even more, the IF NOTCH Filter
(described later) may also be used, in conjunction with these filter systems, to significant advantage.
NOTCH, CONT/APF
The NOTCH center frequency can be returned
to the initial value by pressing and holding the
[NOTCH] key.
The center frequency of the set contour and the
center frequency of the audio peak filter can be re-
turned to their initial values by pressing and holding
the [CONT/APF] key.
Inner Knob (NOTCH)
Rotate the inner [NOTCH] knob to adjust the cen-
ter frequency of the IF NOTCH filter. Press the
[NOTCH] key to turn the IF NOTCH filter ON or
OFF.
The null position of the IF NOTCH filter can be ob-
served on the display.
Additionally, the display will show the center fre-
quency of the IF NOTCH filter for 2 seconds when-
ever the [NOTCH] knob is turned.
Outer Knob (CONT/APF)
The DSP CONTOUR operation can alter the profile
of the passband to partially attenuate an in-band
frequency component.
The CONTOUR operation can be switched ON/
OFF with the [CONT/APF] Key.
The influence of CONTOUR is depicted graphically
on the display.
If there is interference or noise during CW opera-
tion, the APF center frequency is automatically set
to the CW PITCH frequency as a "peak filter", to
make it easier to hear the desired signal.
APF operation is switched ON/OFF with the [CONT/
APF] key.
The location of the APF peak frequency is graphi-
cally illustrated on the display.
When the knob is turned, the center fre-
quency of NOTCH, the center frequency
of CONTOUR, or the Peak Frequency shift
width of the of the APF will be illustrated on
the display for 2 seconds.
Using IF SHIFT and WIDTH Together
A B
Desired Signal Desired Signal
QRM
QRM QRM
IF BANDWIDTH IF BANDWIDTH
C
Desired Signal
QRM
QRM
QRM
IF BANDWIDTH
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