Post-correlation temporal nulling

Abstract

A post-correlation nulling circuit (,) derives from a narrowband jammer a replica of the baseband jammer noise which is used to adaptively cancel the jammer noise waveform in the receiver baseband after PN processing, thus allowing the adaptive antenna spatial nulling to concentrate on canceling wideband jammers. In particular, the post-correlation nulling circuit (,) includes a correlator (,) for correlating the received interference signal and received code modulated signal with a replicate code to generate an interference noise signal and a demodulated signal, a first processor (,) (,) for generating actual orthogonal interference signals based upon the actual interference noise signal, a generator (,) for producing a replicate interference signal having a frequency and waveform substantially similar to the received interference signal, a second processor (,) (,) for generating replicate orthogonal signals based upon the replicate interference signal and encoding the replicate orthogonal signals with the replicate code to generate replicate noise signals, a weighting network (,) (,) for weighting the replicate noise signals to generate weighted replicate noise signals, and a combiner (,) for combining the weighted replicate noise signals with the actual orthogonal interference signals produce a sum signal (,) in which the actual orthogonal interference signals are nulled.