Icom IC-475H Instruction Manual page 30

7-3 АСС OPERATION
7-4 NOISE BLANKER (МВ)
OPERATION
1) Push [NB] SWITCH.
COMP PREAMP AGC NB
7-5 SUBAUDIBLE ТОМЕ
ENCODER AND 1750Hz
TONE CALL OPERATIONS
(1) Subaudible tone encoder operation
(2) 1750Hz Tone Call operation
The 1C-475H has a fast attack/slow release AGC system which
maintains a peak voltage of a rectified IF signal from the IF ampli-
fier circuit for a brief period of time.
This circuit prevents irritating background noise from being heard
during the short pauses in speech. The damping effect of the AGC
therefore allows accurate S-meter readings to be taken of peak IF
signal strength.
1) For normal SSB reception:
Select the SLOW (OUT) position.
For CW reception or for SSB signals with short interval fading:
Select the FAST (IN) position.
2) The AGC function does not work in FM mode.
This operation effectively reduces unwanted pulse-type noise from
outside sources such as ignition noise from vehicles.
1) Push the [NB] SWITCH.
2) The noise blanker may not work as.well when strong signals are
on nearby frequencies or when the noise is continuous rather
than pulse-type.
Subaudible Tone Encoder (U.S.A., Australia versions)
The built-in tone encoder allows access to repeaters which require
a subaudible tone superimposed on the transmit signal.
1750Hz Tone Call (Europe, Sweden versions)
An audible 1750Hz tone signal may be generated for the purpose of
accessing repeaters.
The tone frequency can be programmed into each memory channel
independently.
1) Select a memory channel you want to program the tone fre-
quency in for the VFO modes or MEMORY CHANNEL mode.
2) Push the [TONE] SWITCH to turn ON the tone encoder function.
3) Push the [SET] SWITCH and rotate the TUNING CONTROL to
select the desired tone frequency.
4) Push the [SET] SWITCH again to program the tone frequency.
The [TONE] SWITCH alternately turns ON and OFF the tone
encoder function.
Push the [TONE] SWITCH to open the repeater and hold for
approximately 1 ^ 3 seconds.
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