FT-920 Operating Manual
45
level will enhance the performance of the DSP Noise
Reduction.
To turn the DSP Noise Reduction off, rotate the NR
control fully counter-clockwise.
? As you tune around the band while using the NR
circuit, you may discover that the apparent “pitch”
of the background noise changes somewhat af-
ter you encounter signals. The NR circuit is an
adaptive filter which “form fits” around a signal,
so this observation is completely normal.
Tools for Strong-Signal and
Low-Frequency Operation
Operation on the lower HF Amateur bands (160
through 30 meters) presents special challenges, in-
cluding high atmospheric noise levels, strong local
signals, and a lack of antenna directivity (compared
with higher-frequency multielement beam antennas).
The FT-920 is particularly well equipped to assist the
operator in maintaining reliable communications un-
der these difficult conditions.
The receiver section front end includes a high-inter-
cept doubly-balanced mixer, which provides excel-
lent immunity from intermodulation. For protection
against the ingress of out-of-band signals which can
cause intermodulation, the receiver front end is pro-
tected by a bank of bandpass filters, including spe-
cial high-Q filters for the 7, 14, 21, and 50 MHz bands.
And the built-in Automatic Antenna Tuner may be
engaged on receive, as well as transmit, providing
extra protection against strong signals outside the
current band of interest.
Other features of interest to the operator in strong-
signal environments include:
IPO (Intercept Point Optimization)
The IPO feature reduces the receiver front-end gain
by bypassing the RF preamplifier. When the extra
gain of the preamp is not needed (typically below
about 10 MHz), engaging the IPO feature will reduce
the background noise level and improve the receiver’s
immunity by reducing the signal level presented to
the first mixer. So long as background “band noise”
is still audible, the
useful
sensitivity of the receiver
will not have been reduced by activating the IPO.
To turn this feature on, press the [IPO] key, located
just to the right of the [METER SELECT] key on the left
side of the front panel. The IPO icon on the display
will become illuminated, and the background noise
level should drop. If you have reduced the setting of
the RF GAIN control previously, you may need to ro-
tate it clockwise somewhat after turning on the IPO
feature.
To re-activate the receiver front end’s preamplifier
again, press the [IPO] key again.
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