Abstract
In this paper a digital electronic correlator for analizing vibration and acoustic phenomena is presented. Two signals, to be correlated are, at first, recorded by a multi-channel tape recorder and the reproduced voltage outputs are fed into the analog-to-digital converters of the correlator. Then, the voltage inputs are converted to 4-bit binary numbers at regular sampling intervals. One of these digital signals is transported in shift register delay line and is read out at a later stage to be multiplied with the other signal. Every product of the two signals is shown as number of pulses and is accumulated by a counter.
The shift register has 11 stages and the sampling instant of A-D converters may be shifted stepwise by one-fifths of the sampling interval, within one sampling interval. Therefore, there are 55 sampling combinations in positive and negative time shift respectively. The correlation of the input signals is calculated one by one with these combinations. The number of samples to be calculated may be set arbitrarilly in the correlator.
This device consists of about 400 transistor logical elements and is applicable to the input signals up to 5 kc. Many auto-and cross-correlation functions have been determined with this device. Several of these reults are also shown in this paper.
