Direction Finding on Spread Spectrum Signals Using A Time-Integrating Acousto-Optic Correlator.

A computer simulation and experimental results are presented to show that use of a time integrating acousto-optic correlator can enable the detection and high resolution direction finding of very low power spread spectrum signals. The correlator operates on the outputs of two spatially separated receivers and the output ccf (cross correlation function) is windowed before the Fourier transform is taken to generate the 'time domain filtered cross spectral density' (TDFCSD). Detection is achieved by threshold detection within the amplitude of this TDFCSD, while direction finding is achieved by phase slope estimation.