Twin Pbt Operation - Icom ic-7700 Instruction Manual

■ Twin PBT operation

Shows passband width, shift value and condition
• Filter set screen
• About passband width and shift value on the screen
PBT1
PBT2
• PBT operation example
Both controls in the
center positions
PBT2
IF center frequency
[TWIN-PBT]
PBT-CLR
IF center frequency
Passband's center frequency
SFT: Shift value
BW: Passband width
PBT1
Interference
To reject interference, PBT (Passband Tuning) elec-
tronically narrows the IF passband width by shifting
the IF frequency slightly outside of the IF filter pass-
band. The IC-7700 uses DSP for the PBT function.
Moving both [TWIN-PBT] controls shifts the IF pass-
band center frequency both above and below the re-
ceived frequency.
➥ The LCD graphically shows the passband width
and shift frequency.
• PBT indicator above
is in use.
➥ Hold down
set screen. Current passband width and shift fre-
quency is displayed in the filter set screen.
➥ Hold down
[TWIN-PBT] controls to the center positions.
The PBT is adjustable in 50 Hz steps in the SSB/CW/
RTTY/PSK modes, and 200 Hz in the AM mode.
In this time, the shift value changes in 25 Hz steps in
the SSB/CW/RTTY/PSK modes, and 100 Hz in the
AM mode.
• [TWIN-PBT] should normally be set to the center posi-
tions (PBT setting is cleared) when there is no interfer-
ence.
• When PBT is used, the audio tone may be changed.
• Not available for FM mode.
• While rotating [TWIN-PBT], noise may occur. This
comes from the DSP unit and does not indicate an
equipment malfunction.
Cutting the lower
passband edge
PBT2
PBT1
Passband
Desired signal
5-13
FUNCTIONS FOR RECEIVE
switch lights when PBT
PBT-CLR
for 1 second to enter the filter
FILTER
PBT-CLR for 1 second to set the
Cutting both lower and
higher passband edges
Interference Desired signal
5
PBT2
PBT1
Passband
Interference