A filter processor provides improved capabilities and reduced complexity by inputting and processing lower resolution signals and by generating higher resolution filtered signals. In a preferred embodiment; an incremental filter processor generates incremental input signals, performs incremental processing, and generates multi-bit filtered signals. Input signals are received from radar, sonar, seismic, or other sources; are processed by the filter processor to generate filtered signals; and can be post processed by a post processor. In a preferred embodiment, the input circuit is a serial input and parallel output circuit, such as a delay line or a CCD; the filter processor is an incremental fast Fourier transform processor; and the post processor is an incremental frequency domain correlator. Other post processors include a frequency domain integrator and an RSS post processor to convert coherent signal samples to noncoherent signal samples.