Yaesu FT-2000D, Руководство по эксплуатации

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Page 57 FT-2000D O
PERATING
M
ANUAL
WIDTH
(
IF DSP B
ANDWIDTH
)
T
UNING
(
SSB/CW/RTTY/PKT M
ODES
)
The IF Width tuning system allows you to vary the width of the DSP IF passband, so as to eliminate interference. Moreover,
the bandwidth may actually be
expanded from its default setting, should you wish to enhance incoming signal fidelity when
interference on the band is low.
I
NTERFERENCE
R
EJECTION
(
S
IGNALS WITHIN
3
KHZ
)
Rotate the [ WIDTH
] knob to adjust the bandwidth.
Counter-clockwise rotation reduces the bandwidth, while
clockwise rotation increases the bandwidth.
A
DVICE
:::::
ˆ The IF Width affects the Main band (VFO-A) only.
ˆ The bandwidth of the IF can be observed on the dis-
play.
ˆ The Sub band (VFO-B) frequency display will show
the width of the IF passband for 3 seconds whenever
the [
WIDTH
] knob is turned.
You may disable this feature (displaying the width of
the IF passband) via Menu item “
015 diSP LVL IND .”
See page 117 for details.
C
AUTION
:
When rotating the [ WIDTH
] control fully counter-clock-
wise, the transition between 50 Hz and 25 Hz bandwidth
may be accompanied by a “ping” sound, depending on the
amount of noise present. This is a normal condition, and
you should turn down the volume, when wearing head-
phones, to minimize the amplitude of this momentary
sound.
Referring to Figure B, you can see the default band-
width with the [
WIDTH
] knob set to the 12 o’clock
position.
By rotating the [
WIDTH
] knob to the left, the band-
width will narrow (see Figure “ A ”), while rotation
of the [ WIDTH
] knob to the right, as depicted in
Figure “
C
,” will widen the bandwidth.
The default bandwidths Ú , and total bandwidth ad-
justment range, will vary according to the operat-
ing mode:
SSB Mode : 200 Hz ~ 4.0 kHz (2.4 kHz Ú )
CW Mode: 25 Hz ~ 2.4 kHz (2.4 kHz Ú )
RTTY/PKT Modes: 25 Hz ~ 2.4 kHz (500 Hz Ú )
Ú
: bandwidth at 12 o’clock position of [ WIDTH
] knob.
[WIDTH] Knob
WIDTH Indicator
IF
BANDWIDTH
IF
BANDWIDTH
IF
BANDWIDTH
Using IF Shift and Width Together
The IF Shift and Variable IF Width features together
form a very effective interference-fighting filter-
ing system.
For example, in Figure “ A ” you can see how inter-
ference has appeared both on the high and low sides
of the desired signal. By rotating the [
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, without 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 benefits on the net residual bandwidth.
What’s more, the IF Notch Filter (see the next sec-
tion) may also be utilized, in conjunection with the
three other filter systems, to significant advantage.
A B C
IF
BANDWIDTH
IF
BANDWIDTH
IF
BANDWIDTH
Desired Signal Desired Signal Desired Signal
QRM
QRM QRM QRM
QRM QRM
A B C