Yaesu FTDX101D Operation Manual page 45

APF (Audio Peak Filter)
During CW operation, when interference or noise is
present, the center frequency is automatically set to
the PITCH frequency, making it easier to hear the
desired signal.
The APF function can be operated individually for
MAIN band and SUB band.
1. Rotate the [CONT/APF] knob to the left or right
to reduce any interference.
● Rotate the [CONT/APF] knob to display the cen-
ter frequency (-250Hz - +250Hz) of the audio
peak filter.
● Press and hold the [NOTCH] knob to restore the
APF peak center frequency setting to "0 Hz", and
disable the APF function.
● The display will show the peak position of the
APF, while tuning the SHIFT knob.
The APF bandwidth can be selected from
NARROW / MEDIUM / WIDE via the Menu
item "APF WIDTH" (page 99).
2. To exit from APF operation, press the [APF] key
again.
SHIFT, WIDTH
Inner Knob (SHIFT)
IF SHIFT permits moving the DSP filter passband
higher or lower, without changing the pitch of the
incoming signal, and thus reduces or eliminates in-
terference. Because the tuned carrier frequency is
not varied, there is no need to re-tune the operating
frequency to eliminate the interference.
The total passband tuning range for the IF SHIFT
system is ±1.2 kHz.
The SHIFT function can be operated individually for
MAIN band and SUB band.
Rotate the [SHIFT] knob to the left or right to re-
duce interfering signals.
● Rotate the [SHIFT] knob to display the shift offset
of the IF filter (-1200Hz to +1200Hz).
● Press and hold the [SHIFT] knob to quickly move
the filter passband to center.
● On the filter function display area, you can ob-
serve the direction of the shift.
● While the SHIFT function is active, the indicator
on the left side of the [SHIFT] knob will light.
Refer to Figure "A" and notice the depiction of the
IF DSP filter as a thick line in the center of the
passband.
In Figure "B", an interfering signal has appeared
inside the original passband. In Figure "C", you
can see the effect of rotating the [SHIFT] knob.
The interference level is reduced by moving the fil-
ter passband so that the interference is outside of
the passband.
A B
Desired Signal Desired Signal
QRM
IF BANDWIDTH IF BANDWIDTH
SHIFT knob SHIFT knob
C
Desired Signal
QRM
IF BANDWIDTH
SHIFT knob
43