The FTDX1200 interference-fighting circuitry begins in its "RF" stages, and continues throughout the entire receiver section.
FTDX1200 allows configuration of the features described below.

R.FLT (IF Roofing Filters) Three Roofing filters, of 15 kHz, 6 kHz, and 3 kHz bandwidths, are provided in the First IF, right after the first mixer. These filters are automatically selected to provied narrow-band selectivity to protect the following IF and DSP stages. The automatically selected filter may be manually changed by the operator, if desired, for specila operating circumstances. CONTOUR Filter Thr DSP Contour filter has the unique ability to provide either a null or a peak in tunable segments of the receiver passband. You may suppress interference and excessive frequency components on an incoming signal, or you may peak those tunable segments. The level of the nul or peack, and the bandwidth, over which it is applied, are adjustable via the Menu. IF SHIFP The passband center frequency of the IF DSP filter may be moved up or down by adjusting this control. IF WIDTH The width of the IF DSP filtering may be adjusted using this control.

IF NOTCH The IF Notch filter is a high-Q notch filter that can eliminate, or significantly reduce an interfeiring carrier. DNF (Digital Notch Filter) When multiple interfering carriers are encountered during reception, the Digital Notch Filter can significantly reduce the level of these signals. DNR (Digital Noise Reduction) The DSP's Digital Noise Reduction (DVR) feature utilizes 15 different mathematical algorithms to annalyze and suppress different noise profiles encountered on the 50 MHz/HF bands. Choose the selection that provides the best noise suppression, and allows the signal to rise up out of the noise. AGC The AGC system is highly adaptable to changing signal and fading characteristics, making reception possible under the most difficult conditins.

End of "Receiver Operation (Front End Block Diagram)"