<title>Multichannel optical time-integrating correlator for adaptive jamming cancellation</title>

Abstract

Hardware implementation of the steepest descent algorithm, as applied to multichannel adaptive jamming cancellation, requires the realtime correlation of wide bandwidth signals from multiple input channels. The described optical system uses a single-channel acousto-optic (AO) deflector as an input device for the adapted main antenna signal, where multiple jamming sources mask the target return, and a multichannel AO deflector as the input device for an array of auxiliary antennas, each receiving jamming energy. A time-integrating correlation between the main and auxiliary channels is calculated optically and produces an update to each weight function (stored in computer memory) in accordance with a steepest descent algorithm. The updated weight functions are optically reconstructed and used to tap a multichannel AO delay line, which carries the information from the array of auxiliary channels. A spatial sum of the output from the weighted delay line yields an estimate to the noise in the main channel. The multichannel optical time-integrating correlator has demonstrated realtime parallel computation of the correlation between two wide bandwidth auxiliary channels and the adapted main channel.

Multichannel acousto-optic correlator for time delay computation

“…The unknown signal input is represented by 5(t) = A5(t) e(t) (2) where A(t) and $(t) are the magnitude and phase of the input signal. The +1 diffracted amplitude R(t) from the reference AO cell is given by…”