Abstract: A system and method that rejects interference in a direct-sequence spread spectrum communications system. The system and method implement smooth transitions from hop to hop with minimal transient degradation. Adaptive interference suppression is achieved using a suppression filter and an adaptive algorithm that processes the output of the suppression filter and an estimate of the hopping frequency of the interfering signals to switch between interference filter coefficients of the suppression filter. This creates a notch at the carrier frequency of the interfering signals and rejects interference contained in the communication signals. The interference rejection filter hops with the frequency-hopped spread spectrum interfering signals to maintain its interference rejection capability.

Abstract: A decision feedback equalizer and method that implements blind initialization using an antenna array. The equalizer comprises the antenna array which includes two or more antenna elements that form input paths. Two or more feedforward finite impulse response (FIR) filters are respectively coupled to the two or more antenna elements. An attenuator and a switch are coupled in parallel to outputs of all but one feedforward FIR filter. An adder combines the signals output by the feedforward FIR filters. A decision device is coupled to the output of the adder. A decision feedback FIR filter is coupled to the output of the decision device whose output is fed back to the adder and combined with other signals summed thereby. A switch is coupled between the decision device and the decision feedback FIR filter. The equalizer is initialized using a blind adaptation algorithm.

Abstract: Blind narrow-band interference cancellation apparatus and methods that implement an algorithm that adapts an antenna array or a finite impulse response equalizer, or a combination thereof, to cancel narrow-band interference in a communication signal. The apparatus and methods comprise an algorithm for removing an unknown narrow-band interferer from a communications signal of interest, so that the desired signal may be lock on to. In implementing the cancellation apparatus and methods, the received signal is oversampled either in time or in space. This oversampled signal contains a statistically white component (the signal of interest) and a correlated component (the narrow-band interferer). A prediction-error filter is formed using correlation statistics of the oversampled signal. Filtering the oversampled signal produces an output that is statistically white, containing most of the signal of interest, and a small portion of the interference.

Abstract: Coherent combining apparatus and methods that do not require training to adapt combining weights. The approach employed in the present invention uses phase-lock loops to demodulate input signals. The phase-lock loops are coupled so that their outputs are phase coherent. The outputs of the phase-lock loops are summed to obtain a coherent combining of the input signals. Exemplary embodiments of the present invention comprise two or more phase-lock loops having signal inputs and I and Q data outputs. A combiner sums the I and Q data output by the two or more phase-lock loops. A common decision circuit feeds back the summed output of the combiner to the two or more phase-lock loops and generates phase coherent output signals.