Space/time/frequency methods in adaptive radar - New Jersey ...

61Figure 3.1 Space-time adaptive array architecturewhere x is assumed a zero-mean, circularly symmetric Gaussian random vector withcovariance matrix R. The clutter and noise are assumed to be independent.Under hypothesis H 1 , x is given bywhere a is complex scalar representing the target signal amplitude and phase, and sis the target vector. The target power is denotedThe colored noise (the aggregate of noise+interference+clutter) covariancewhere the superscript denotes transpose andcomplex conjugate, is usually not known, hence an estimate is used instead. Theestimate is derived from range cells in the vicinity of the tested range cell and istermed secondary data . The secondary data consists of clutter returns and, possibly,other interferences, such as jammers. The presence of narrowband jammers doesnot alter the signal model as presented, thus attention is restricted only to clutter