Yaesu FT-897D, Руководство по эксплуатации

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Page 27 FT-897D O
PERATING
M
ANUAL
DSP CW P
EAKING
F
ILTER
In the CW mode, pressing the [ C
](
DBF
) key in Multi Func-
tion Row “p” [
DNR
,
DNF
,
DBF
] activates a narrow-band-
width peaking filter, which may be ideal for use under very
crowded conditions. The DSP CW Peaking Filter also is
especially helpful under VHF/UHF weak-signal situations.
The center frequency of the DSP CW Peaking Filter is auto-
matically aligned to be centered on the response you have
selected via the Menu Mode in item
No-027
[
CW PITCH
] .
See page 57 for details.
To change the bandwidth of the DSP CW Peaking Filter:
1. Press and hold in the [ C
](
DBF
) key for one second on
the CW mode. This instantly activates Menu Mode No-
045 [ DSP BPF WIDTH
]
, which allows selection of the
bandwidth of the DSP CW Peaking Filter.
2. Rotate the
DIAL
to select the desired bandwidth. The
available values are 60 Hz, 120 Hz, and 240 Hz (default
value: 240 Hz).
3. When you have made your selection, press and hold in
the [ F
] key for one second to save the new setting and
return to normal operation.
DSP N
OISE
R
EDUCTION
(
NR
)
The Noise Reduction feature of the DSP system may be used
to enhance signal-to-noise ratio on weak signals.
1. Press the [
DSP
] key momentarily. This instantly acti-
vates Multi Function Row “p” [ DNR , DNF , DBF
].
2. Press the [ A
](
DNR
) key to activate the DSP Noise Re-
duction feature. “Parentheses” will appear on the both
sides of the “
DNR ” indication, and the “ DSP ” will ap-
pear at the center top on the display.
3. Now press and hold in the [
A ](
DNR
) key for one sec-
ond. This instantly activates Menu Mode No-049
[
DSP
NR LEVEL
] , which allows adjustment of the DSP Noise
Reduction level.
4. Rotate the DIAL to find the point where best signal-to-
noise ratio is obtained under the current noise condi-
tions.
5. Press and hold in the [ F
] key for one second to save the
new setting and exit to normal operation.
6. To turn off the DSP Noise Reduction feature, press the
[
A
](
DNR
) key again.
If noise is present at a level which causes indi-
cation on the S-meter, the performance of the
Noise Reduction filter may be enhanced by ro-
tating the SQL/RF (RF Gain) control in a counter-clock-
wise direction so as to set the (fixed) S-meter reading at
the same level as the noise peaks. This adjustment raises
the AGC threshold of the receiver.
DSP N
OTCH
F
ILTER
The DSP system’s Notch Filter may be helpful in removing
one or more offending carrier or heterodyne signals from
the audio passband.
1. Press the [
DSP
] key momentarily. This instantly acti-
vates Multi Function Row “p” [ DNR , DNF , DBF
].
2. Press the [ B
](
DNF
) key to activate the Notch Filter. “Pa-
rentheses” will appear on the both sides of the “ DNF ”
indication, and the “ DSP ” will appear at the center top
on the display. You will notice that the audio level of the
carrier signal is now being reduced.
3. Press the [ B
](
DNF
) key once more to turn the Notch
Filter off.
Do not activate this filter in the CW mode, as
incoming CW signals will be notched out of the
audio passband!
R
ECEIVER
A
CCESSORIES
60 Hz
120 Hz
240 Hz