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Abstract
Time domain processing of broadband signals requires the use of steering delays. In this work a postbeamformer interference canceler (PIC) processor for processing broadband directional signals without using steering delays is investigated. As the frequency domain PIC processor structure is able to avoid steering delay requirements, this thesis analyzes the performances of the frequency domain PIC processor with two interference beamformer methods to cancel interference and to avoid signal suppression. An improved interference beamformer (IIB) method is proposed and presented for the frequency domain PIC processor for processing broadband directional signals which completely removes the interference present in the signal beam for sinusoidal signals. At the same time this method does not require pre-steering delays. Analytical expressions for various performance measures are derived for the PIC processor using the IIB method and the effects of various parameters on the performance are studied by computer simulation. An orthogonal interference beamformer (OIB) method using projection technique is also studied for the PIC processor for processing broadband directional signals. When an OIB method is used, the interference beam does not contain the desired signal and the signal does not get canceled from the signal beam in the subtraction process. Again the target beam is constrained to have unity response in the target direction. Analytical expressions for various performance measures are derived. The effects of various parameters on the performance of PIC processor using the OIB method are studied and analyzed. Examples using computer simulation are presented to describe the performance of PIC processor using the OIB method. The performances of the PIC processor is compared using these methods for processing broadband signals. The comparison of various performance measures is carried out by varying various system parameters using analytical expressions derived in the thesis and by numerical examples. A multichannel PIC processor is proposed and studied to cancel multiple directional unwanted interferences by forming multiple interference beams. Multichannel PIC processor is capable of steering a beam in any direction of interest and can cancel multiple broadband directional interferences. Both the IIB method and the OIB method are extended to be utilized in multichannel PIC processor.