Yaesu FT-847 handleiding
Handleiding
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38
FT-847 OPERATING MANUAL
DSP NOISE REDUCTION
The Digital Signal Processing (DSP) circuitry includes
a highly-effective NOISE REDUCTION feature, which may
be used alone or in conjunction with the IF NOISE
BLANKER. The DSP NOISE REDUCTION circuit can be ef-
fective against a wide variety of noise types; it is not
limited to the “impulse” noise such as ignition noise.
However, because the NOISE REDUCTION is effected in
the audio stage, the operator may have to work around
the effects of the AGC circuitry. Here’s how to use the
DSP NOISE REDUCTION feature:
•
To turn the NOISE REDUCTION feature on,
press the [NR] switch. The “
NR
” icon
will appear on the display. You should
notice a significant reduction in the back-
ground noise.
‚
If the noise is strong enough to be mov-
ing the S-Meter (thereby indicating that AGC volt-
age is being produced by the strong noise level),
you may find the DSP NOISE REDUCTION to be more
effective if you take one of the following steps:
l Switch off the RF PREAMPLIFIER;
l Engage the RF ATTENUATOR; or
l Rotate the RF (GAIN) control counter-clockwise
until the S-meter reading “hangs” at the peak S-
Meter reading on the noise.
ƒ
The level of noise reduction applied by the DSP
may be adjusted via Menu #11. The default set-
ting, on an arbitrary scale of
0
(minimum noise
reduction) to
15
(maximum noise reduction) is
7
.
A higher setting will provide more noise quieting,
with slightly degraded fidelity; a setting lower than
7
will improve received signal quality, but with
slightly less-effective noise reduction.
„
To turn the DSP NOISE REDUCTION feature off, press
the [NR] switch again. The “
NR
” icon will disap-
pear from the display.
OPERATION
RECEIVER FEATURES
SQUELCH
(
RECEIVER MUTING
)
The SQUELCH circuit allows muting of the receiver’s
audio circuits during operating sessions where you
wish to quiet the receiver except when a signal is
present.
To set the proper sensitivity thresh-
old for the SQUELCH circuit, rotate the
SQL control clockwise until the
background noise just disappears.
This threshold point provides the best
sensitivity to weak signals, while en-
suring proper quieting during quiescent periods.
When a signal is received which exceeds the thresh-
old set by the SQL control, the muting function will
be disabled and normal receiver audio will flow. When
the signal disappears, the receiver will again be muted.
To disable the SQUELCH system’s muting action, rotate
the SQL control fully counter-clockwise.
The SQUELCH circuitry is most often used during FM
operation, but the FT-847’s SQUELCH system is opera-
tional in all modes. There are additional muting func-
tions associated with FM operation (CTCSS and DCS),
and these are described on page 53.
VOICE SYNTHESIZER
The FT-847 includes the capability for the use
of the (optional) FVS-1A VOICE SYNTHESIZER,
which provides an audible announcement of
the current operating frequency (receive fre-
quency).
To confirm the current frequency, press the [VOICE]
key, located between the MAIN VFO Tuning Dial and
the AF/RF (GAIN) controls. Frequency resolution to
the displayed 100 Hz digit is provided. For example,
if the frequency is 145.910.0 MHz, the FVS-1A will
announce: “One-Four-Five-Point-Nine-One-Zero-Zero.”
Note: The VOICE SYNTHESIZER announces the receive fre-
quency; in “Split” operation, the receive fre-
quency is displayed on the SUB VFO frequency
display field.
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Productinformatie
| Merk | Yaesu |
| Model | FT-847 |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 17150 MB |
