Twin Pbt Operation - Icom IC-7800 Instruction Manual

5
FUNCTIONS FOR RECEIVE

■ Twin PBT operation

[TWIN PBT] for main
[PBT CLEAR] for main [PBT CLEAR] for sub
Shows filter width, shifting value and condition
• PBT operation example
Both controls at
center position
PBT1
IF center frequency
[TWIN PBT] for sub
Cutting a lower
passband
PBT2
Interference
General PBT (Passband Tuning) function electronically
narrows the IF passband width by shifting the IF fre-
quency to slightly outside of the IF filter passband to
reject interference. This transceiver uses the DSP cir-
cuit for the PBT function. Moving both [TWIN PBT]
controls to the same position shifts the IF.
➥ The LCD shows the passband width and shift fre-
quency graphically.
➥ Push [FILTER] for 1 sec. to enter the filter set
screen. Current passband width and shift frequency
is displayed in the filter set screen.
➥ To set the [TWIN PBT] controls to the center posi-
tions, push [PBT CLR] for 1 sec.
The variable range depends on the passband width
and mode. The edge of the variable range is half of the
passband width, and PBT is adjustable in 25 or 50 Hz
steps.
• [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.
PBT1
PBT2
Passband
Desired signal Interference
5-12
Cutting both higher and
lower passbands
PBT1
PBT2
Passband
Interference
Desired signal