Operation of an adaptive processor using a photorefractive parallel integrator

Abstract

A parallel optical technique for use in the adaptive processing of radar signals is described. We have demonstrated such a technique in an acousto-optic adaptive signal processing system designed to null the jamming of radar signals. This system features a time integrating correlator using a new type of photorefractive spatial light modulator exhibiting high levels of contrast, resolution, uniformity and sensitivity. Using this system we have demonstrated nulling of both narrow and wide band RF signals. The operation of the photorefractive integrating device, its performance and that of the overall system are discussed.

Wideband operation of a photorefractive-based adaptive processor

“…3 The optical adaptive signal processor, discussed in this paper, uses a Bi12Si o.o(BSO) photorefractive crystal as a time integrating device and achieves greater than 30-dR cancellation of CW gnals over a 5-MHz band centered at 40 MHz. 2 This paper reports on the cancellation of wideband noise signals (>100kHz bandwidth) using a photorefractive based optical adaptive signal processor. The adaptive optical processor concept is described in Section 2 of this paper.…”

“…The main antenna receives the signal where s(t) is the target return and N0(t) is the jammer noise received in the main antenna. The receivedjammer noise is expressed as a multiple delayed version of the ja-mmer source N0(t) = AcE1 n(t+t) (2) where M is the nmnber of multipath reflections, A is the received gain of the mth multipath and torn S the time delay of the mth multipath of noise source n(t). The auxiliary antenna in Fig.…”