Techniques are considered for processing the outputs of a sensor array that is observing

distinct signal sources. Three types of wideband signals are discussed: unknown, stochastic, and parameterized. Narrowband signals are a special case. Four types of random errors are discussed: additive sensor noise, sensor gain errors, sensor time-delay errors, and "beam-pointing\´ errors. It is concluded that the so-called decoupled-beam data processor is a very promising technique, which can be implemented by passing the output of

individual "beams" through a

-input,

-output linear system. When sensor gain-delay and beam-pointing errors are not present, the decoupled-beam data processor provides "infinite sidelobe rejection."