Squelch Function; Functions For Fm; Functions For Ssb/Cw - Icom IC-R8500 Instruction Manual

■ Squelch function

The IC-R8500 has 2 types of squelch, noise squelch
and S-meter squelch.
Noise squelch: Only acts on noise; has good sen-
sitivity. It can be adjusted for reception of weak sig-
nals. Strong signals exceeding a certain level will
always cause the squelch to open.
S-meter squelch: S-meter squelch does not open
for weak signals but can be adjusted to open for sig-
nals over a wide range of strengths. Once you have
selected a threshold point in a range, the IC-R8500
will open for all signals above this point.
To adjust the squelch, rotate [SQUELCH].
• Clockwise rotation closes the squelch (sets the thresh-
old point higher); counterclockwise rotation opens the
squelch (for reception of weak signals).

■ Functions for FM

D Center indicator
FM signals have a wide bandwidth which makes
them easy to receive. However, you may be tuned
off-center resulting in audio distortion. The IC-R8500'
s off-center indicators appear in such cases, making
it easy to fine tune to the center of the frequency.
D AFC
AFC stands for automatic frequency control. The AFC
circuit automatically compensates the tuning when a
receive frequency drifts or goes off frequency.
When one of the off-center indicators appears, the
IC-R8500 can adjust the receive frequency auto-
matically—when the AFC function is turned ON and
an off-center frequency is received, the frequency
in the display automatically changes to reflect the
center of the signal.

■ Functions for SSB/CW

D IF shift
The IF shift function electronically changes the
center of the IF (intermediate frequency) passband
frequency to reject interference. The IF shift is not
available in FM and AM modes.
q Adjust the [SHIFT] control for a minimum interfer-
ence signal level.
• The audio tone may be changed while the IF shift is in
use.
w Set the shift control to its center position when
there is no interference.
Noise squelch
threshold (not
available in SSB,
CW, WFM and
AM narrow modes)
When [SQUELCH] is
S
rotated past center,
the S-meter shows
the signal strength
needed to open the
squelch.
RECV
One of these indicators appears when the received
signal is off-center.
AFC
RECV
When one of these indicators appears, the
displayed frequency is automatically moved to the
center frequency.
APF IF SHIFT APF
Shifts low Center
RECEIVE FUNCTIONS
S-meter squelch
threshold
• Signals below the
S-meter level
are muted.
1 3 5 7 9 + 20dB + 60dB
SIGNAL
IF SHIFT APF IF SHIFT
Shifts high
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