Automatic Gain Control; Noise Blanker - Icom IC-RSOOCOL Instruction Manual

7-3 AUTOMATIC GAIN
CONTROL (AGC)
[AGC] switches
7-4 NOISE BLANKER
(NB LEVEL]
Tech Talk from Icom
Q. Why does the receiver need AGC?
A. AGC is necessary to output signals constantly from
the speaker regardless of the strength of incoming
signals.
Signals of varying strengths enter the receiver circuit
through the antenna connector. In SSB or CW
mode especially, signal strength changes a lot from
the wave characteristics.
AGC reduces the receiver gain when a strong signal
is received, preventing distortion of speaker output.
After strong signals disappear the receiver gain
returns to the original gain. AGC automatically
controls the receiver gain.
FUNCTIONS RECEIVING /
AGC holds audio output constant during fluctuations in
signal strength. AGC. keeps irritating background noise
from being heard during the short pauses in speech.
OFF POSITIONS:
Used when receiving a very weak signal located near
stronger signals. In this case, the [RF GAIN] control is
useful for reducing receive gain.
The S-meter does not move when the AGC is set to OFF.
# The received audio may be distorted when a strong signal
is received.
FAST POSITION:
Normally used when receiving a signal with short interval
fading such as in CW or FSK mode, or when searching for a
signal with the main dial.
SLOW POSITION:
Normally used when receiving a signal in SSB mode.
In FM, WFM or AM mode, use the "SLOW" or "FAST"
positions.
The noise blanker effectively reduces interference from
pulse-type noise such as car ignition systems and wide
pulse-type noise known as "'woodpecker" noise.
1) Push the [NB] switch ON.
2) Adjust the [NB LEVEL] control as required depending
on the noise level.
3) To suppress "woodpecker" noise and other wide
pulse-type noise, push the [NAR/WIDE] switch ON
("WIDE" is set).
AGC "slow" or 'fast' selects the return speed of
the receiver gain from the reduced gain to the
original gain. By holding the receiver gain for short
periods, AGC constantly emits receive signals from
the speaker and signals can be comfortably heard.
One aspect of AGC is that very weak signals located
near stronger signals may be blocked when the AGC
is set in the "slow" or "fast'' position. AGC is
therefore equipped with an OFF position for times
when you wish to receive very weak signals without
reducing receiver gain.
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