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4
USING DIFFERENT OPERATING MODES
Band keys
[CW/RTTY]
[AF]
Tuning dial
Normal
Reverse
170 Hz
170 Hz
2125 Hz
2125 Hz
BFO
BFO
Space
Space
Mark
Mark
4-3 Operating RTTY (FSK)
Å
RECEIVING
Before operating RTTY be sure to consult the manual
that came with your TNC.
➀
Connect RTTY capable TNC and personal computer
or an RTTY terminal (p. 68)
➁
Push a band key to select the desired band.
➂
Push [CW/RTTY] to select RTTY.
➃
Rotate [AF] to set audio to a comfortable listening
level.
➄
Rotate the tuning dial to set the desired frequency.
• S-meter indicates received signal strength.
• If the received signal cannot be demodulated, try select-
ing RTTY-R mode.
■
ABOUT RTTY REVERSE MODE
Received characters are occasionally garbled when
the receive signal is reversed between MARK and
SPACE. This reversal can be caused by incorrect TNC
connections, setting, commands, etc. To receive a re-
versed RTTY signal correctly, select RTTY-R mode.
✔
Convenient functions for receive
q
Preamplifier and attenuator (p. 38)
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.
w
Noise blanker (p. 39)
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.
e
Noise reduction (p. 40)
The noise reduction function reduces noise compo-
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.
r
Twin PBT (passband tuning) (p. 41)
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.
t
AGC (auto gain control) (p. 39)
The AGC controls receiver gain to produce a constant
audio output level even when the received signal
strength is varied by fading, etc.
y
1/4 function (p. 39)
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.
DSP
Summary of Contents for IC-746
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