A special-purpose computer for automatic target recognition

A description is given of Starloc (Sandia target Location computer) a special-purpose computer designed for automatic target recognition. It is motivated by the lock-and-tumbler (LAT) filter algorithm, a generalized matched filter that can detect targets regardless of variations in their appearance. Starloc´s fault-tolerant structure of pipelined, parallel floating-point processors and memories efficiently performs two-dimensional correlation, the major computational kernel of the algorithm. The LAT filter algorithm correlates the input image with a set of ten to twenty filter kernels, each containing all of the information about the target and its variations, using a phase multiplexing scheme. Starloc implements the LAT algorithm correlations in the Fourier domain by transforming the image to the Fourier domain, performing pixel-by-pixel multiplication with a filter kernel represented in the domain, and then inverse-transforming the product. The last processing step is updating the target value for each pixel. Hot-standby processors and incorporating a comprehensive set of error checkers provide fault tolerance. A reduced-scale prototype has been constructed, and an advanced design using digital signal processors for increased speed is described