Icom IC-7700 - Manual (Page 74)

4-22
D D About BPSK and QPSK modes
BPSK and QPSK modes are available for PSK31.
• BPSK (Binary Phase Shift Keying) mode is the most
commonly used mode.
• QPSK (Quadrature Phase Shift Keying) mode has
error correction capability to provide better decoding
than BPSK mode in marginal condition. However,
more accurate tuning is required with QPSK mode,
due to the tight phase margin of QPSK.
q During PSK mode selection, push [F-3•DECODE]
to display the PSK decode screen.
w Push [F-1•<MENU1>] to select PSK decode second
menu.
e Push [F-2•B/QPSK] to toggle between BPSK and
QPSK mode alternately.
<
MENU1
>
F-1
DECODE
F-3
B/QPSK
F-2
4
RECEIVE AND TRANSMIT
• PSK decode screen— BPSK mode
• PSK decode screen— QPSK mode
• 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.
• 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.
• 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.
• 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.
• 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.
• Fine tuning (p. 3-7)
➥
During PSK, make sure that the kHz tuning step
function is OFF (no “
Z ” indication), push and hold
[TS] for 1 sec.
• PSK may not be decoded correctly using the 10 Hz
step tuning.
• 1 ⁄ 4 function (p. 3-6)
➥
Push [1/4] to turn the 1 ⁄ 4 function ON and OFF.
NOTCH
NOTCH
AGC VR
PBT-CLR
PBT-CLR
NR
NR
NB
NB
NB
D D Convenient functions for receive