Essex has developed a hybrid acousto-optic/digital electronic processor, called the Advanced Optical Processor (AOP) a.k.a. Wideband Range-Doppler Imager (WRDI), that generates high dynamic range, high resolution range-Doppler images from wideband radar returns. This processor supports high resolution processing necessary for target discrimination and kill assessment. The processor is described and results of testing with simulated and real field data are presented. Key capabilities of this processor are: (1) high dynamic range to detect small cross section targets in a severe clutter background, (2) large image sizes in multiples of 1024 range bins by up to 128 Doppler resolution bins, (3) dynamically adjustable Doppler resolution, (4) dynamic reconfigurability of modules to switch between coarse range resolution covering a large range extent for acquisition mode to a fine resolution mode for target discrimination, (5) the ability to accommodate time compression/dilation to eliminate blurring of moving targets in high resolution range-Doppler images, and (6) the ability to efficiently combine multiple low bandwidth, low range resolution radar returns to obtain high range resolution range-Doppler images. The AOP can process true arbitrary waveforms, which are needed to support the high dynamic range required for discrimination. This is achieved in a compact, light weight and cost effective package.
Optoelectronic processing provides significant advantages for space applications. These advantages include enhanced processing capability with reduced size, weight and power. Design considerations that are unique to space can have a significant impact on the development schedule. Optoelectronic processors are most efficient at operations that involve correlation, Fourier transforms, or a combination of these functions. Several application areas where these functions are used are presented along with the rationale for using optoelectronics. Two key applications include telecommunications switching and radar processing. Synthetic Aperture Radar (SAR) processing in space is discussed as a specific example.
Proc. SPIE. 2754, Advances in Optical Information Processing VII
KEYWORDS: Radar, Digital signal processing, Optical signal processing, Doppler effect, Image processing, Fourier transforms, Optoelectronics, Signal processing, Radar signal processing, Channel projecting optics
Essex has been involved in quadratic processing research and the design of processors that compute these algorithms for the past 14 years. We are developing a more efficient processor (Labyrinth-II<SUP>TM</SUP>) that has higher dynamic range (greater than 100 dB) and enhanced throughput (approximately 70 times faster). Labyrinth-II<SUP>TM</SUP> is a unique half-rack integration of non-developmental units that provides the compute power to solve complex signal processing tasks with significantly reduced latency. The architecture is a flexible combination of high-speed laser optics and digital technologies that is readily configured by the customer to perform a variety of functions. One or two signals can be input to the processor for linear or quadratic processing. The new processor is much simpler, more compact, and more flexible than predecessors. This paper presents a description of this new workstation accelerator. The functions generated by this processor are the ambiguity function, Wigner-Ville function, and cyclic spectrum. Other functions that can be represented by two signal inputs can also be generated by this accelerator. Some applications include high resolution spectral analysis, radar waveform processing, signal detection and characterization, geolocation using time and frequency differences of arrival, and direction finding using angle of arrival.
Essex has developed a hybrid acousto-optic/digital electronic processor, called Hawkeye<SUP>TM</SUP>, that generates high dynamic range, high resolution range-doppler images from wideband radar returns. The processor is described and results of laboratory tests of a partially completed breadboard version are presented. Key capabilities of this processor are: high dynamic range to detect small cross section targets in a severe clutter background; large image sizes of 1024 or greater range bins by up to 128 doppler resolution bins; dynamically adjustable doppler resolution and dynamic reconfigurability of modules to switch between coarse range resolution covering a large range extent for acquisition mode to a fine resolution mode for target discrimination; the ability to accommodate time compression/dilation to eliminate blurring of moving targets in high resolution range-doppler images; and, the ability to efficiently combine multiple low bandwidth, low range resolution radar returns to obtain high range resolution range-doppler images. This is achieved in a compact, lightweight, and cost effective package.
Transitioning optical processors from the laboratory to rugged environments requires special care during the design of the optical and mechanical components as well as the total package configuration. Processors exist today that were developed to operate in various rugged environments while maintaining performance specifications. Designing optical processors for space environments requires additional consideration of features such as radiation, launch vibration, thermal cycling, heat dissipation, self calibration, and autonomous operation. This paper presents the design of processors which operate in rugged environments, and the rules that must be adapted/extended space operation. Specific experience and general conditions are presented on existing processors and those under development. The status of radiation hardened components is also presented.
This paper presents descriptions of and results from two quadratic processing workstation accelerators. One of these workstations is used for radar processing and the other two for signal detection and characterization. These workstations exhibit high dynamic range and real-time performance in compact packages. The functions generated by these systems are the ambiguity function, Wigner-Ville function, and cyclic spectrum. Two of these systems are complete and the other is under development.