Icom IC-7600, Инструкция по эксплуатации, Страница: 92 / 196

83
4
RECEIVE AND TRANSMIT
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Twin PBT operation
<MODE> SSB/CW/RTTY/PSK/AM
In general, the PBT (Passband Tuning) electronically
narrows the IF passband width by shifting the IF
frequency to slightly outside of the IF filter passband,
to reject interference. The IC-7600 uses DSP for the
PBT function.
You can watch the nearby intended signal using the
spectrum scope. (p. 69)
Rotate
q
[PBT1] (inner control) and [PBT2] (outer
control) to the opposite direction from each other to
narrow the IF passband width.
• Before rotating, the PBT settings of
[PBT1] and [PBT2]
should be cleared.
• Rejects interference of both higher and lower
passbands. If you rotate the control too much, the
received audio may not be heard because the
passband width is too narrow.
• Displays the passband width and shift frequency.
• The indicator on the
[PBT-CLR] switch lights.
• Hold down
[PBT-CLR] for 1 second to clear the PBT
setting. In that case, indicator on the [PBT-CLR] switch
goes OFF.
• The variable range depends on the passband width and
the operating mode. The edge of the variable range is
half of the passband width. The PBT is adjustable in 25
Hz steps in the SSB/CW/RTTY/PSK modes, and 100 Hz
in the AM mode.
• Moving both [TWIN PBT] controls to the same position
shifts the IF left or right.
Hold down
w
[FILTER] for 1 second.
• The Filter screen is displayed. The current passband
width and shift frequency are displayed.
Push
e
[EXIT/SET].
• Exits the Filter screen.
NOTE: While rotating the [TWIN PBT] controls,
noise may be heard. This comes from the DSP unit
and does not indicate an equipment malfunction.
PBT2
PBT1
PBT2
PBT1
PBT2
PBT1
IF center frequency Desired signal Interference Interference Interference
Cutting the lower
passband
Desired signal
Passband Passband
PBT is OFF Cutting both higher and
lower passbands
• PBT operation example
[TWIN-PBT]
PBT-CLR
FILTER F-4
DEF
Shows filter width, shifting value and condition
“SHARP” is selected.
• Filter screen when operating [TWIN PBT]
• About Passband width and Shift value on the
screen
PBT1
PBT2
IF center frequency
Passband’s center frequency
SFT: Shift value
BW: Passband width
• When operating [TWIN PBT]