Filter
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36
IF FILTER
The IF filters are designed for selecting the exact range
of intermediate frequencies that are sent to the next
stage in the receive circuit. Interference adjacent to the
desired signal can be reduced by selecting a narrow
bandwidth filter and/or shifting the center frequency of
the filter.
To more effectively remove interference, use the IF
filters with the DSP filters described on pages 37
and38.
CHANGING IF FILTER BANDWIDTH
When adjacent frequency interference is present at both
sides of the desired signal, a narrow IF filter bandwidth
may be the best way to remove the interference.
Changing the filter bandwidth will not effect the current
receive frequency.
To use a narrow filter in SSB, CW, or FSK mode, install
the appropriate optional filter {page 58}, and select the
appropriate setting in Menu No. 46.
When in CW or FSK mode, the wide filter or the narrow
filter is automatically selected, depending on the
bandwidth of the DSP filter that you select. Refer to
“CHANGING RECEIVE BANDWIDTH” {page 37}. The
default in SSB or AM mode is wide bandwidth. In FM
mode, you cannot change the filter bandwidth.
Note:
When you use Menu B, make sure to select the appropriate
filter bandwidth via Menu No. 46 in Menu B.
1 Select SSB or AM mode.
2 Press [FILTER].
• The current filter selection appears.
3 Turn the MULTI/CH control to select Wide
(“FIL-WID”) or Narrow (“FIL-NAR”).
4 Press [FILTER] to complete the setting.
REJECTING INTERFERENCE
IF SHIFT
For SSB, CW, or FSK mode, shifting the center
frequency of the filter pass band is an additional method
of fighting adjacent frequency interference. Shifting this
center frequency does not change the current receive
frequency.
To remove interference that is higher in frequency than
the desired signal, turn the IF SHIFT control
counterclockwise. To remove interference that is lower
in frequency than the desired signal, turn the IF SHIFT
control clockwise.
NOISE BLANKER
Noise Blanker was designed to reduce pulse noise such
as that generated by automobile ignitions. Noise
Blanker does not function in FM mode.
Press [NB] to toggle Noise Blanker ON or OFF.
• “NB” appears when the function is ON.
Interfering
signal
Desired
signal
Interfering
signal
Desired
signal
Interfering
signal