Icom IC-7700 - Manual (Page 66)

4-14
D D About RTTY reverse mode
Received characters are occasionally garbled when
the received signal has Mark and Space tones re-
versed. This reversal can be caused by incorrect TNC
connections, setting, commands, etc. To receive re-
versed RTTY signals correctly, select RTTY-R mode.
➥
During RTTY mode, push and hold for
1 sec. to select RTTY and RTTY-R mode.
D D Twin peak filter
The twin peak filter changes audio frequency response
by boosting the mark and space frequencies (2125 and
2295 Hz) for better reception of RTTY signals.
➥
During RTTY mode, push to turn the twin
peak filter ON and OFF.
• “ ” appears in the LCD and the [APF/TPF] indicator
above this switch lights green while the filter is in use.
NOTE: When the twin peak filter is in use, the re-
ceived audio output may increase. This is a normal,
not a malfunction.
TPF
APF/TPF
RTTY/PSK
APF/TPF
Normal Reverse
Space Mark BFO Space Mark BFO
170 Hz 2125 Hz 170 Hz 2125 Hz
4
RECEIVE AND TRANSMIT
• Preamp (p. 5-9)
➥
Push [P.AMP] (MF3) several times to set the pre-
amp OFF, preamp 1 ON or preamp 2 ON.
• “P.AMP1” or “P.AMP2” appears when the preamp 1 or
preamp 2 is ON.
• Attenuator (p. 5-9)
➥
Push [ATT] (MF4) several times to set the attenu-
ator in 6 dB steps.
• Push and hold [ATT] (MF4) for 1 sec. to turn the atten-
uator function OFF.
• “ATT” and attenuation level appear when the attenu-
ator is ON.
• Noise blanker (p. 5-16)
➥
Push to turn the noise blanker ON and
OFF, and then rotate [NB] control to adjust the
threshold level.
• Noise blanker indicator (above switch) lights
when the noise blanker is ON.
• Push and hold for 1 sec. to enter noise blanker
set mode.
• Twin PBT (passband tuning) (p. 5-12)
➥
Rotate [TWIN PBT] controls (inner/outer).
• PBT indicator (above switch) lights when
PBT is in use.
• Push and hold for 1 sec. to clear the set-
tings.
• Noise reduction (p. 5-17)
➥
Push to turn the noise reduction ON and
OFF.
• Rotate [NR] control to adjust the noise reduction
level.
• Noise reduction indicator (above switch) lights
when the noise reduction is ON.
• Manual notch filter (p. 5-18)
➥
Push to turn the manual notch function
ON and OFF.
• Rotate [NOTCH] control to set the attenuating fre-
quency.
• Notch indicator (above switch) lights when
the manual notch is ON.
• AGC (auto gain control) (p. 5-11)
➥
Push [AGC] switch several times to select
AGC FAST, AGC MID or AGC SLOW.
➥ Push to turn the AGC time constant
manual setting ON and OFF.
• Rotate [AGC] control to adjust the time constant.
• 1 ⁄ 4 function (p. 3-6)
➥ Push [1/4] to turn the 1 ⁄ 4 function ON and OFF.
AGC VR
NOTCH
NOTCH
NR
NR
PBT-CLR
PBT-CLR
NB
NB
NB
D D Convenient functions for receive