Yaesu FT DX 9000MP Operation Manual page 73

With reference to Figure (B), note the initial posi-
tion (12 o'clock) of the [ CONTOUR ] control when
the [ CONT ] switch is pushed. You may observe
the "indentation" in the receiver passband where
the Contour filter is placing a low-Q "notch" (per
the setting of Menu #086 and 088, referenced
above). Counter-clockwise rotation (to the left) of
the Contour knob causes the indentation to move
toward a lower frequency within the passband,
while clockwise rotation (to the right) causes the
indentation to move toward a higher frequency
within the passband. By removing interference or
unwanted frequency components on the incoming
signal, it is possible to make the desired signal rise
out of the background noise/interference, enhanc-
ing intelligibility.
A B
IF IF
BANDWIDTH BANDWIDTH
FT 9000MP O
DX PERATION
I I I I I
NTERFERENCE NTERFERENCE NTERFERENCE
NTERFERENCE NTERFERENCE
CONT ( C
ONTOUR
C
IF
BANDWIDTH
M
ANUAL
R R R R R
EJECTION EJECTION EJECTION
EJECTION EJECTION
) C
O
ONTROL PERATION
Q Q Q Q Q
The steep slopes of the DSP filtering can, when
adjusted aggressively, impart an unnatural sound
to an incoming signal. Oftentimes, though, a nar-
row bandwidth is not the key to improving copy;
the incoming signal itself may have undesirable or
excessive frequency components, especially in the
low-frequency range around 400 Hz. By judicious
use of the Contour filter, the "shoulder" of the pass-
band response may be altered, or components re-
moved from within the passband, allowing the de-
sired signal to rise above the background noise and
interference in a manner not obtainable with other
filtering systems.
In the CW mode, press and hold the [ CONT ] switch
for 2 seconds to activate the APF (Audio Peak Fil-
ter) which provides a very narrow audio bandwidth;
the LED inside the button will blink umber for 3
seconds, then replaces to continuous glow.
(S (S (S (S (S 3 3 3 3 3
IGN IGN ALS ALS WITHIN WITHIN
IGNALS IGN IGN ALS WITHIN ALS WITHIN WITHIN
P P P P P
UICK UICK UICK UICK UICK OINT OINT OINT OINT OINT
N N N N N
O O O O O TE TE TE TE
TE
Page 71
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