Interference Rejection (Signals Within 3 Khz); Contour Control Operation - Yaesu FT-2000D Operating Manual

The Contour filtering system provides a gentle perturbation of the IF filter passband, so as to suppress or enhance certain
frequency components, thus enhancing the sound and/or readability of a received signal.
1. Press the [ CONT ] button. The Contour notation will
appear in the display to confirm that the Contour filter
is engaged.
2. Rotate the [ CONTOUR ] knob to achieve the most
natural-sounding audio reproduction on the incoming
signal.
3. To cancel Contour tuning, press the [ CONT ] button
once more.
A :
DVICE
The Contour filter affects the Main band (VFO-A) only.
You may observe the graphically-depicted peak posi-
tion of the CONTOUR Filter in the CONTOUR indi-
cator on the display.
[ CONTOUR ] knob
Fully Clockwise
[ CONTOUR ] knob
Center
[ CONTOUR ] knob
Fully Counter-Clockwise
C G "M
ONTOUR AIN INUS
The Sub band (VFO-B) frequency display will show
the CONTOUR frequency for 3 seconds whenever the
[ CONTOUR ] knob is turned.
You may disable this feature (displaying the CON-
TOUR frequency) via Menu item "015 LVL IND." See
page 117 for details.
The Contour filter's level (either nulling or peaking) may
be adjusted using Menu item "092 rdSP CNTR LV."
The factory default setting is for a null of "–15
The bandwidth over which the Contour filter effect is
applied may be adjusted using Menu item "093 rdSP
CNTR WI." The factory default setting is "10
When the optional DMU-2000 Data Management Unit
is connected, the Audio Scope (on the "Oscilloscope"
page) is particularly useful when adjusting the Con-
tour control. Not only can you see the effect of the
null/peak of the Contour system, but you also can see
the position of the null/peak with respect to frequency
components of interest on the incoming signal. You
may then observe (on the Audio Scope) the effect of
the Contour control while listening to the effect on the
signal, and this will help build your intuition on how
best to use Contour tuning in the future.
Q P :
UICK OINT
The steep slopes of the DSP filtering can, when adjusted aggressively, impart an unnatural sound to an incoming signal.
Oftentimes, though, a narrow 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 100-400 Hz. By judicious use of the
Contour filter, the "shoulder" of the passband response may be altered, or components removed from within the passband,
allowing the desired signal to rise above the background noise and interference in a manner not obtainable with other
filtering systems.
FT-2000D O
PERATING
I
NTERFERENCE
CONTOUR C
[ CONTOUR ] knob
Fully Clockwise
[ CONTOUR ] knob
Center
[ CONTOUR ] knob
Fully Counter-Clockwise
" C G "P
ONTOUR AIN LUS
–15" (dB).
–15 –15 –15
10 10 10." 10
M
ANUAL
R
EJECTION ( S
O
ONTROL PERATION
With reference to Figure "B," note the initial posi-
tion (12 o'clock) of the [ CONTOUR ] knob when
the [ CONT ] button 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 item "092," referenced above).
Counter-clockwise rotation (to the left) of the
[ CONTOUR ] knob causes the indentation to move
towered 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
IF
BANDWIDTH
IGNALS WITHIN
CONTOUR Indicator
[ CONTOUR ] Knob
B C
IF IF
BANDWIDTH BANDWIDTH
)
3
KHZ
[ CONT ] Button
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