Digital interference suppression system for radio frequency interference cancellation

Abstract

A digital signal processing system that produces an adaptive cancellation arrangement which nulls out all types of concurrent interference and/or jamming signals received by a Global Positioning System (GPS) or spread spectrum receiver from diverse antennas. The present invention uses a unique adaptive interference suppression technique to convert and digitize the analog input signals, and numerically modulate the data to produce effective cancellation of interference signals by nulling while preserving the multiple underlying spread spectrum signals. The invention generates digital and analog output signals which contain a reduced amount of interference. In the present arrangement, orthogonal components of the composite received signal are separated by the receive antenna arrangement and adjusted in the digital network between the antenna and receiver in phase and amplitude to optimally cancel components. The arrangement can be synergistically combined with digital adaptive transversal filter technology which is primarily used to supplement suppression performance by reducing narrowband interferences in the band. The orthogonal received signal components from the GPS satellite constellation and from interference sources are combined in the present arrangement to adaptively create a null that attenuates interference sources while slightly modifying the GPS received signals.

Dependencies are inferred from the claim text.