A high-speed correlator

Abstract

The correlation function, $\phi_{ij}^{(\tau)} = \lim_{T \rightarrow \infty} {1 \over T} \int^{T}_{o} f_{i}(t)f_{j}(t-\tau) dt$ is of great interest today because of its use in the fields of oceanography and meteorology and because of its recent applications in the field of communication. Various machines, both analog and digital, have been designed for the automatic computation of correlation functions. The machine described in this paper differs from those which have previously been described in the literature in that the speed with which it computes the integral above for each value of τ i is mainly limited by the minimum value of T permissible for a precision of a few per cent.