High Speed Correlator

Abstract

The real time computation of the correlation function of two signals of up to 2.5 MHz bandwidth at 30 points simultaneously has been achieved to an accuracy of better than 3% of reading ±2% of full scale by a probabilistic computational procedure. An oscilloscope display permits ``live'' observations. The maximum delay between the input signals can take values between 3 μsec and 48 msec, corresponding to delay increments of 0.1 μsec to 1.6 msec, derived from a crystal oscillator. The instrument offers an order of magnitude improvement in bandwidth and a decisive advantage in cost over commercially available units, while retaining compact size (23×48×38 cm). These features, as well as greatly simplified construction, were made possible by the extensive use of integrated circuits. The computational procedure and critical circuitry are described in detail, with briefer treatment given to auxiliary circuits and construction.