Delay lattice filter for radar doppler processing

In a pulse doppler radar signal processor which processes successive echo interpulse period (IPP) signalling in accordance with range cell samples, an adaptive filter for enhancing the discrimination of targets from clutter and noise, said filter having a delay lattice configuration including a plurality of cascadedly coupled lattice stages, each adapted to operate on the range cell samples of first and second complex signal inputs, a lattice stage comprising:

• means for delaying said second complex signal input over a time interval to render the delayed range cell samples thereof, corresponding to a previous IPP, coherent with the range cell samples of said first complex signal input corresponding to a current IPP;
• means for computing independently a first coefficient signal and a second coefficient signal for each range cell sample of said current IPP based on respective separate functions of a common multiplicity of coherent range cell samples of said first and delayed second complex signal inputs, said common multiplicity of coherent range cell samples being grouped about said range cell sample for which said first and second coefficient signals are being computed;
• first means for weighting each range cell sample of said first complex signal input with the second coefficient signal correspondingly computed therefor;
• second means for weighting each range cell sample of said delayed second complex signal input with the first coefficient signal correspondingly computed therefor;
• first means for combining each range cell sample of said first complex signal input corresponding to a current IPP with said coherent weighted range cell sample of said delayed second complex signal input to form a first complex signal output of the lattice stage;
• and
• second means for combining each range cell sample of said delayed second complex signal input corresponding to a current IPP with said coherent weighted range cell sample of said first complex signal input to form a second complex signal output of the lattice stage.