GB1246642A - Signal correlation apparatus - Google Patents

Abstract

1,246,642. Selective signalling. SANDERS ASSOCIATES Inc. 3 Sept., 1968, No. 41933/68. Heading G4H. [Also in Division H4] In a system for identifying an unknown signal which is known to be one of a set of signals characterized, e.g. by their frequencies or by their patterns of pulses, the unknown signal is amplified and limited and shifted, by relatively high frequency clock-pulses, along a row of a core matrix-which then stores an " image " of the signal-the row is then read-out to a plurality of " correlation networks " each of which comprises an array of resistors connected in various combinations to the column output lines in such a way that each corresponds to one of the set of known signals, and in operation the correlation network that produces the highest output identifies the unknown signal. As described a plurality of unknown signals, Fig. 2, are read into the rows of a core matrix, which are then read out, sequentially, row-by-row, to the correlation networks of which two only are shown, namely two capable of identifying a 4 kc/s. and a 5 kc/s. signal, and the figure also shows, at the bottom, the images that 4 kc/s. and 5 kc/s. signals produce. The correlation networks shown are designed on the assumption that the signals to be recognized are read-out to the correlation networks " in phase " with the first column. In practice this will not be so and it would be necessary to have a group of correlation networks for each signal to be recognized. According to the Specification a group of three networks 60 degrees out of phase with each other, will, if their outputs are commoned, produce outputs which are at worst 86% of the output that would be produced by in phase signals with an in phase correlation network.