D Convenient Functions For Receive; D About Bpsk And Qpsk Modes - Icom IC-7700 Instruction Manual

4
RECEIVE AND TRANSMIT
D D Convenient functions for receive
• Preamp (p. 5-9)
➥ Push [P.AMP]
(MF3)
amp 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]
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
NB
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
set mode.
• Noise reduction (p. 5-17)
➥ Push
to turn the noise reduction ON and
NR
OFF.
• Rotate [NR] control to adjust the noise reduction level.
• Noise reduction indicator (above
when the noise reduction is ON.
D D About BPSK and QPSK modes
< >
MENU1 B/QPSK
F-1 F-2
• PSK decode screen— BPSK mode
• PSK decode screen— QPSK mode
several times to set the pre-
for 1 sec. to turn the atten-
(MF4)
switch) lights
NB
for 1 sec. to enter noise blanker
switch) lights
NR
DECODE
F-3
• Twin PBT (passband tuning) (p. 5-12)
➥ Rotate [TWIN PBT] controls (inner/outer).
• PBT indicator (above
PBT is in use.
• Push and hold
tings.
• 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 and OFF.
• Rotate [AGC] control to adjust the time constant.
• Manual notch filter (p. 5-18)
➥ Push
NOTCH
ON and OFF.
• Rotate [NOTCH] control to set the attenuating fre-
quency.
• Notch indicator (above
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 ⁄ function (p. 3-6)
4
➥ Push [1/4] to turn the
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 [DECODE]
to display the PSK decode screen.
w Push [<MENU1>]
ond menu.
e Push [B/QPSK]
QPSK mode alternately.
4-22
switch) lights when
PBT-CLR
for 1 sec. to clear the set-
PBT-CLR
to turn the AGC time constant
to turn the manual notch function
switch) lights when
NOTCH
1 ⁄ function ON and OFF.
4
to select PSK decode sec-
F-1
to toggle between BPSK and
F-2
F-3