This work extends the constant false alarm rate (CFAR) detection methodology to detection in the presence of two independent interference sources with unknown powers. The proposed detector is analyzed on the assumption that clutter and jammer covariance structures are known and have relatively low rank properties. The limited-dimensional subspace-based approach leads to a robust false alarm rate (RFAR) detector. The RFAR detection algorithm is developed by an adaptation and extension of Hotelling's principal-component method. The detector performance loss and false alarm stability loss to unknown clutter and jammer powers have been evaluated for example scenario.

In this paper, a new narrowband beamformer with derivative constraint is developed for wideband and coherent jammers suppression. The so-called IQML algorithm with linear constraint, which is used to estimate the unknown directions of the jammers in signal-free environment, is shown to be an inappropriate constraint estimator. In this paper, a new IQML algorithm with a norm constraint is considered, which is a consistent estimator and can be used to achieve desired performance. It can be also employed in the CDMA system for MAI suppression. We show that it outperforms the approach with the linear constraint used in the narrowband beamformer, in terms of directional pattern, output SINR and nulling capability for wideband and coherent jammers suppression.