D Convenient Functions For Receive; D About Rtty Reverse Mode; D Twin Peak Filter - Icom IC-7700 Instruction Manual

4
RECEIVE AND TRANSMIT

D Convenient functions for receive

• Preamp (p. 5-9)
➥ Push [P.AMP]
(MF3)
preamp OFF, preamp 1 ON or preamp 2 ON.
• Push and hold [P.AMP] (MF3) for 1 sec. to turn the
preamp function OFF.
• "P.AMP1" or "P.AMP2" appears when the preamp 1
or preamp 2 is ON.
• Attenuator (p. 5-9)
➥ Push [ATT] several times to set the attenu-
(MF4)
ator in 6 dB steps.
• Push and hold [ATT]
attenuator function OFF.
• "ATT" and attenuation level appear when the attenu-
ator is ON.
• Noise blanker (p. 5-16)
➥ Push NB to turn the noise blanker ON or
OFF, and then rotate [NB] control to adjust the
threshold level.
• Noise blanker indicator (above
when the noise blanker is ON.
• Push and hold
NB
er set mode.
• Twin PBT (passband tuning) (p. 5-12)
➥ Rotate [TWIN PBT] controls (inner/outer).
• PBT indicator (above
PBT is in use.
• Push and hold
PBT-CLR
tings.

D About RTTY reverse mode

Normal
170 Hz 2125 Hz
Space Mark
BFO

D Twin peak filter

several times to set the
for 1 sec. to turn the
(MF4)
switch) lights
NB
for 1 sec. to enter noise blank-
switch) lights when
PBT-CLR
for 1 sec. to clear the set-
Reverse
2125 Hz 170 Hz
Space Mark
BFO
APF/TPF
• Noise reduction (p. 5-17)
➥ Push NR to turn the noise reduction ON or
OFF.
• Rotate [NR] control to adjust the noise reduction
level.
• Noise reduction indicator (above
when the noise reduction is ON.
• Manual notch filter (p. 5-18)
➥ Push NOTCH
tion ON or OFF.
• Rotate [NOTCH] control to set the attenuating fre-
quency.
• Notch indicator (above
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
AGC VR
manual setting ON or OFF.
• Rotate [AGC] control to adjust the time constant.
• ⁄ function (p. 3-6)
1
4
➥ Push [1/4] to turn the
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
1 sec. to select RTTY and RTTY-R mode.
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
twin peak filter ON or OFF.
• " " appears in the LCD and the [APF/TPF] indicator
TPF
above this switch lights green while the filter is in use.
NOTE: When the twin peak filter is in use, the
received audio output may increase. This is a nor-
mal, not a malfunction.
4-14
switch) lights
NR
to turn the manual notch func-
switch) lights when
NOTCH
to turn the AGC time constant
⁄ function ON or OFF.
1
4
RTTY/PSK
APF/TPF to turn the
for