Method and apparatus for excision of narrowband interference signals in navigation or communication bands

A method for suppressing narrowband interference, comprising:

• down-converting an incoming signal to an intermediate frequency (IF) signal;
• digitizing said intermediate frequency signal using an analog-to-digital converter;
• inputting said digitized signal to a fast Fourier transform to produce a plurality of contiguous frequency bins;
• examining said frequency bins to identify those bins containing narrowband interference above an excision threshold as excise bins;
• excising said excise bins to leave residual bins;
• implementing a lower resolution FFT analysis receiver to monitor broadband components and to mask out the narrowband interference excised in the excising step;
• reconstructing the signal with said residual bins using an inverse fast Fourier transform;
• up-converting said reconstructed signal;
• and
• outputting said up-converted signal to a receiver as a protected signal having improved signal characteristics through reduced narrowband interference, said protected signal being used to produce enhanced operation in said receiver.

A narrowband interference excision and nulling system, comprising:

• a first bank of narrowband filters utilizing a continuous fast Fourier transform process on an incoming digitized signal containing a signal of interest to produce a plurality of contiguous frequency bins for each of a first channel and a second channel;
• a frequency excision processing unit for determining which of said frequency bins to excise based upon an excision threshold computed using bin and band statistical parameters with a narrowband mask, and for excising the determined bins;
• a lower resolution analysis FFT receiver to monitor broadband components and to mask out narrowband interference signals excised by the frequency excision processing unit;
• a post-processor to determine narrowband interference signal content output from the second channel;
• and
• a second bank of narrowband filters utilizing an inverse fast Fourier transform process to reconstruct said signal of interest for each of the first channel and the second channel, said reconstructed signal having improved signal characteristics through reduced narrowband interference therein.