Icom IC-746 Instruction Manual page 23

q Preamplifier and attenuator (p. 38)
w Noise blanker (p. 39)
e Noise reduction (p. 40)
r Twin PBT (passband tuning) (p. 41)
t AGC (auto gain control) (p. 39)
y 1/4 function (p. 39)
Convenient functions for receive
The preamp amplifies received signals in the front end
circuit to improve the S/N ration and sensitivity. The at-
tenuator prevents a desired signal from distorting
when very strong signals are near the desired fre-
quency or when very strong electric fields, such as
from a broadcasting station, are near you.
The noise blanker is used to reduce pulse-type noise
caused by vehicle ignition systems and key clicks from
strong CW signals on nearby frequencies.
The noise reduction function reduces noise compo-
DSP
nents and picks out desired signals which are buried
in noise. This function digitally transposes receive
audio components to produce desired AF frequency
characteristics at the IF stage.
The PBT function electronically narrows the receiver's
IF passband widths to reduce interference. Moving
both [TWIN PBT] controls to the same position shifts
the IF.
The AGC controls receiver gain to produce a constant
audio output level even when the received signal
strength is varied by fading, etc.
Normally, one rotation of the tuning dial changes the
frequency by about 5 kHz (in 10 Hz tuning steps).
Using the 1/4 function sets the tuning dial so that one
rotation changes the frequency by about 1.25 kHz (in
10 Hz steps). This is convenient for critical tuning.
USING DIFFERENT OPERATING MODES
4
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