Interference Rejection (Signals Within 3 Khz); Contour Control Operation - Yaesu FT-2000 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 [ CONTOUR ] 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 [ CONTOUR ] but-
ton once more.
A :
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 ] button
Fully Clockwise
[ CONTOUR ] button
Center
[ CONTOUR ] button
Fully Counter-Clockwise
C G "M
The Contour filter's level (either nulling or peaking)
may be adjusted using Menu item "090 rdSP CNTR
LV." The factory default setting is for a null of "–15"
(dB).
The bandwidth over which the Contour filter effect is
applied may be adjusted using Menu item "091 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 :
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
I
NTERFERENCE
CONTOUR C
[ CONTOUR ] button
Fully Clockwise
[ CONTOUR ] button
Center
[ CONTOUR ] button
Fully Counter-Clockwise
" C G "P
M
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 [ CONTOUR ] button is pushed. You may ob-
serve the "indentation" in the receiver passband
"
where the Contour filter is placing a low-Q "notch"
(per the setting of Menu item "090," referenced
above). Counter-clockwise rotation (to the left) of
the [ CONTOUR ] knob causes the indentation to
move towered a lower frequency within the pass-
band, 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 ] Button
CONTOUR Indicator
[ CONTOUR ] Knob
B C
IF IF
BANDWIDTH BANDWIDTH
)
3
KHZ
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