Page 58 FT-2000D OPERATING MANUAL
I
NTERFERENCE
R
EJECTION
(
S
IGNALS
WITHIN
3
KHZ
)
IF NOTCH FILTER OPERATION
(
SSB/CW/RTTY/PKT/AM MODES
)
The IF Notch filter is a highly-effective system that allows you to slice out an interfering beat note or other carrier signal
from inside the receiver passband.
1. Press the
[
NOTCH
]
button. The Notch characteristic
will appear in the display to confirm that the Notch
filter is engaged.
2. Initially, rough adjustment of the center frequency of
the IF Notch Filter is adjusted using the outer
[
COARSE
]
knob; thereafter, fine tuning of the Notch
frequency is adjusted using the inner
[
FINE
]
knob.
3. To switch the IF Notch filter off, press the
[
NOTCH
]
button once more. The Notch notation will turn off,
confirming that the IF Notch filter is no longer operat-
ing.
ADVICE:
The IF Notch filter affects the Main band (VFO-A)
only.
You may observe the graphically-depicted peak (maxi-
mum null) position of the IF Notch Filter in the NOTCH
indicator on the display.
The Sub band (VFO-B) frequency display will show
the Notch frequency for 3 seconds whenever the
[
NOTCH
]
knob is turned.
You may disable this feature (displaying the Notch fre-
quency) via Menu item “015 LVL IND.” See page 117
for details.
The width of the IF Notch null may be adjusted using
Menu item “094 rdSP NOTCH W.” Both “Wide” and
“Narrow” selections are available, with “Narrow” pro-
viding the least disruption of the “desired” signal.
When the optional DMU-2000 Data Management Unit
is connected, the effect of the IF Notch filter may be
observed on the Audio Scope (on the “Oscilloscope”
page). The Notch will be observed as a “dip” in the
noise platform observed. What’s more, the “Waterfall”
display may be used to observe the effect of the IF
Notch filter, which will appear as a white area in the
colored background area. The tuning rate for the IF
Notch is somewhat slow while you adjust the
[
FINE
]
knob, so the use of the Waterfall display to confirm
proper adjustment is highly recommended.
The performance of the IF Notch filter is shown in
Figure “A,” where the effect of rotation of the
[
NOTCH
]
knobs is depicted. In Figure “B,” you
can see the notching effect of the IF Notch filter as
you rotate the
[
NOTCH
]
knobs to eliminate the
incoming interference.
[
NOTCH
]
Button
[
NOTCH
]
Knob
NOTCH Indicator
IF
BANDWIDTH
QRM
(Heterodyne)
QRM
(Heterodyne)
IF
BANDWIDTH
Desired Signal Desired Signal
AB
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