Simple analog correlator.

An analog correlator has been constructed using a delay unit which is realized by simulation of the sixth-order Pade approximated result of exp(-jomegatau) where j= radical-1, omega the angular frequency of the signals of concern, and tau the delay in seconds. Several sinusoidal signals and a noise spectrum have been autocorrelated with this correlator; also, it has been applied to determine the impulse response of an RC low-pass filter. Results are in good agreement with theoretical predictions. This correlator has been used to study low- frequency signals in the region 1-50 kHz.