Performance criteria for narrowband array processing

This paper examines the use of various performance criteria for the design of processors in narrowband sensor array systems. These systems consist of an array of sensors (antennas, hydrophones, seismometers, etc.,) the outputs of which are combined in a processor to give an output which is optimal under the particular performance criteria of interest. Such systems allow the separation of a desired signal from a background of both directional and isotropic interference. For wide bandwidth signals these processors generally consist of linear filters, which for implementation purposes are approximated by tapped delay lines in each channel of the array. For the relatively narrowband problems being addressed by this paper (such as those concerned with jam resistant r-f radar and communications systems) these processors consist of complex weights in each channel (or in-phase and quadrature channels). Two types of arrays have proven useful in different applications. The conventional array as illustrated in Fig. 1 and the signal aligned array as shown in Fig. 2 where direction of arrival information is used to co-phase the desired signal in each channel.