Optical Processing of Microwave Signals for Small Satellite Payloads

For low altitude small satellite applications performing electronic surveillance or communication transponding missions highly capable payloads are needed. Generally these spacecraft have low dwell times over the areas of interest and must receive, or search for, signals over a wide frequency band. This paper presents an approach to the implementation of optical processing in complex electronic systems intended to receive and operate on multiple radio frequency (or microwave) signals. The goal is to exploit the rapidly expanding field of linear and nonlinear optics to synthesize transponders and receiving systems for satellites and other platforms. The inputs are assumed to be microwave. The outputs are assumed to be microwave or electronic (digital). In between, the signal operations are performed optically. The focus of the effort is in the architecture for the electronic functions, that allow optical component realization. These elements perform the signal processing operations of: pulse signal detection and pulse parameter estimation; modulation and demodulation of AM, PM, and PM carriers; phase locked loop signal tracking; carrier element mixing (frequency shifting); signal filtering; and signal matched filter detection. The spatial optical processing of ordinary time waveform signals offers significant potential benefits. It inherently provides wide bandwidth, high carrier frequency, and fast response processing capability. A signal Fourier transforms can be performed with a simple lens. The second spatial dimension for parallel processing enhances the capability for exhaustive search of a signal space for parameters of interest. The two-dimensional optical implementation of switching and routing matches the channelized nature of many current communication systems. Increased optical implementations of electronic systems can take advantage of the rapid technological growth in applications and devices in this parallel discipline of optics to effect greater capabilities for the 1990\u27s