Yaesu FT-991 Operating Manual

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Page 43FT-991 O PERA T ING M ANUALdigitAl notch Filter (dnF) operAtionThe Digital NOTCH Filter (DNF) is an effective beat-canceling filter that can null out a number of interfering beat notesinside the receiver passband. Because this is an Auto-Notch feature, there is no adjustment knob associated with this fil-ter.A dvice :If a very strong interfering carrier is encountered, we recommend you first use the IF NOTCH filter, as it is the most ef-fective notching tool in the receiver section.1. Press the F(M-LIST) button, then touch [DNF] onthe LCD. The “DNF” will appear in the display.To disable the Digital NOTCH Filter, just repeat theabove procedure, touching [DNF] on the LCD to choose“OFF”. The “DNF” will turn off, confirming that theDigital NOTCH Filter is not active.digitAl noiSe reduction (dnr) operAtionThe Digital Noise Reduction (DNR) system is designed to reduce the level of random noise found on the HF and 50MHz bands, and it is especially effective during SSB operation. By setting the Menu item “110 DNR LEVEL”, any of 15different noise-reduction algorithms can be selected; each of these algorithms was created for dealing with a differentnoise profile. You will want to experiment with the DNR system to find the best setting corresponding to the noise cur-rently being experienced.1. Press the F(M-LIST) button, then touch [DNR] onthe LCD. The “DNR” will appear in the display.To disable the DNR system, just repeat the above proce-dure, touching [DNR] on the LCD to choose “OFF”. The“DNR” will turn off, confirming that the DNR system isnot active.inTerferenCe reJeCTionF(M-LIST) ButtonF(M-LIST) Button