<title>Time-Integrating Optical Correlator</title>

Abstract

A time-integrating optical correlator was designed and built to detect the presence and relative delay of a digital signal buried in both synchronous and random noise. The system accepts a digital reference signal at data rates from 1 Mb/s to 100 Mb/s and cross correlates this with an analog signal of up to 200 MHz bandwidth. The output correlation covers a relative delay of 1 microsecond with a resolution of 3 ns. The correlation is performed in an optical subsystem employing two acousto-optic Bragg cells. Integration time can be varied from 2 ms to several minutes. Preprocessing of the incoming data, combined with digital postprocessing of the output from the optical subsystem results in correlation gains of over 50 dB. Greater data rates, delay range and bandwidths can be readily achieved