Width; (Interference Rejection "Signals Within 3 Khz") - Yaesu FT-450 Operation Manual

C
ONVENIENCE
WIDTH ( I
The IF Width tuning system allows you to vary the width of the DSP IF passband with three steps (FM: two
steps), so as to eliminate interference. Moreover, the bandwidth may actually be
setting, should you wish to enhance incoming signal fidelity when interference on the band is low.
1. Press the [ DSP ] button several times to set the
" " icon to the "WIDTH" indicator of the DSP
Graphic Display on the display, to enable adjust-
ment of the bandwidth by the [ DSP/SEL ] knob.
2. Rotate the [ DSP/SEL ] knob to adjust the band-
width. Counter-clockwise rotation reduces the
bandwidth, while clockwise rotation increases the
bandwidth.
Referring to Figure "B", this is default band-

width.

By rotating the [ DSP/SEL ] knob to the left,
the bandwidth will narrow (see Figure "A",
while rotation of the [ DSP/SEL ] knob to the
right, as depicted in Figure "C", will widen the
bandwidth.
A
IF
BANDWIDTH BANDWIDTH
DSP/SEL DSP/SEL
The default bandwidths, and total bandwidth
adjustment range, will vary according to the
operating mode:
SSB Mode: 1.8 kHz / 2.4 kHz / 3.0 kHz
(Nominal: 2.4 kHz).
CW Mode: 500 Hz / 1.8 kHz / 2.4 kHz
(Nominal: 1.8 kHz).
AM Mode: 3.0 kHz / 6.0 kHz / 9.0 kHz
(Nominal: 6.0 kHz).
FM Mode: 2.5 kHz / 5.0 kHz
(Nominal: 5.0 kHz).
Page 30
F
EATURES
NTERFERENCE
B C
IF IF
BANDWIDTH
DSP/SEL
R
EJECTION "S
IGNALS WITHIN
"WIDTH" Indicator
[ DSP/SEL ] knob
Using IF Shift and Width Together
The IF Shift and Variable IF Width features
together form a very effective interference-
fighting filtering system.
For example, in Figure "A" you can see how
interference has appeared both on the high
and low sides of the desired signal. By rotat-
ing the [ DSP/SEL ]( WIDTH ) knob, as shown
in Figure "B", the interference from one side
can be eliminated, and by re-positioning the
[ SHIFT ] knob (Figure "C"), the interference
on the opposite side can be removed, with-
out re-introducing the interference previously
eliminated in Figure "B".
Advice: For best interference reduction, the
Width and Shift features are the primary tools
you should use. After narrowing the bandwidth
(Width) and/or adjusting the center of the
passband (Shift), the Contour control may
also yield additional signal-enhancement ben-
efits on the net residual bandwidth. What's
more, the IF Notch Filter (see the next sec-
tion) may also be utilized, in conjunction with
the three other filter systems, to significant
advantage.
A
Desired Signal
QRM
QRM
IF
BANDWIDTH
FT-450 O
)
3 "
KHZ
from its default
[ DSP ] button
B C
Desired Signal Desired Signal
QRM
QRM QRM
IF IF
BANDWIDTH
BANDWIDTH
-SHIFT+
DSP/SEL
M
QRM