Detection of a Pattern in Unknown Position

In this paper, the problem of detecting an optical pattern in unknown position is considered. Two detection procedures are investigated--one which entails a search procedure, and one which does not. The falsealarm and false-dismissal probabilities for these two procedures are evaluated under certain simplifying assumptions in order to compare the two procedures with each other and with the detector which is optimum when the position of the pattern is known. It is shown tnat there is a tradc-o££between error rate and information rate. The procedure requiring a search technique processes the data less rapidly, but at the same time achieves a lower error rate for a given signal-to-noise ratio. This analysis also applies to the problem of detecting a signal with unknown arrival time provided that the assumptions stated herein are satisfied.