Yaesu FT-991 Operating Manual

Also see for FT-991: Manual Manual Operating manual Reference book Instruction manual

Page 42FT-991 O PERA T ING M ANUALinTerferenCe reJeCTioniF notch Filter operAtion (SSb/cw/rtty/dAtA/AM ModeS)The IF NOTCH filter is a highly effective system that allows you to slice out an interfering beat note or other carriersignal from inside the receiver passband.1. Press the F(M-LIST) button, then touch [NOTCH]on the LCD to activate the Notch filter. The DSPgraphic display will illuminate and the current “null”position of the NOTCH filter will appear in theNOTCH indicator on the display. The MULTI knobfunctions as the Notch adjustment knob.2. Rotate the MULTI knob to adjust the “null” positionof the Notch filter.3. To cancel the NOTCH filter, touch [NOTCH] onthe LCD. The graphic disappears from the NOTCHindicator on the display, confirming that the NOTCHfilter is no longer in operation.A dvice :Alternate touches of [NOTCH], will switch theNOTCH filter between on and off.A dvice : The bandwidth of the NOTCH filter (either narrowor wide) may be adjusted using Menu item “114IF NOTCH WIDTH”. The factory default setting is“WIDE”.The performance of the IF NOTCH filter is illus-trated in Figure “A”, where the effect of rotationof the MULTI knob is depicted. In Figure “B”you can see the notching effect of the IF NOTCHfilter as you rotate the MULTI knob to eliminatethe interfering heterodyne.A BDesired Signal Desired SignalQRM(Heterodyne)QRM(Heterodyne)IF BANDWIDTH IF BANDWIDTHMULTIF(M-LIST) Button