A solid optic correlator has been designed and built for the Transition of Optical Processing to Systems program. The correlator has real-time input and multiple rewriteable Fourier filters. The system is interfaced to a workstation for filter development and operation. System design and integration test data are described in this reported. Anticipated system performance is provided.
Martin Marietta is conducting a TOPS Optical Pattern Recognition Program which will culminate in 1994 with an automatic target recognition flight demonstration using a UH-1 helicopter flying a Fiber Optic Guided Missile mission profile. The flight demonstration will be conducted by the US Army Missile Command and supported by Martin Marietta and will involve detecting, locating and tracking an M60A2 tank positioned among an array of five vehicle types. Current status of the TOPS program will be given.
A need for very high probability of detection in modern passive Electronic Combat systems has stimulated development of receivers with ever-wider bandwidths. As receiver bandwidths increase, some portions of the RF spectrum will begin to have a probability of signal overlap approaching unity. Wideband receivers, when operating in these environments with increasing signal densities and new modern modulation techniques, must incorporate computationally intensive algorithms within the receiver architecture to ensure reliable performance. Acousto-optic processing subsystems offer a real- time solution to several of the computationally intensive signal processing functions required in wideband EW systems. The status of the Electronic Warfare Channelize, an acousto-optic subsystems that is being developed by DARPA with the Naval Research Laboratory for the military will be discussed in this paper.
The acousto-optic (AO) module described in this paper is an in-line, time- integrating correlator architecture that detects and analyzes inherently wide bandwidth signals in a small and lightweight package. The correlator processes a 500 MHz instantaneous bandwidth to provide enhanced detection capability for broadband signals. The existing electronic support measures (ESM) testbed processes a wide bandwidth but can only detect the presence of narrowband signals. This paper will describe the AO correlator design and the radio frequency and digital interface required for the insertion into the ESM testbed.
An acousto-optic (AO) range-Doppler processor is being developed to interface to an advanced ground-based radar system developed by the U.S. Army Missile Command (MICOM). The AO processor will replace the function of several digital processor boards currently in the radar. The primary objective of this program is the demonstration of an optical processor in the MICOM radar. This paper provides an overview of the MICOM radar system, discusses the design of the AO range-Doppler processor, and describes the RF and digital electronic interfaces required to achieve real-time operation in the MICOM radar.
We describe the current status of a hybrid optical processor being developed for real-time synthetic aperture radar (SAR) image formation. The processor is being developed for insertion into the ERIM spotlight mode SAR airborne data collection system under the ARPA TOPS program monitored by the Army Research Lab. A 2D Fourier transforming time-integrating interferometrically based optical processor is a key element of the system. The optical processor uses a modulated laser diode for radar signal insertion, crossed 1D acousto-optic scanners for 2D scanning, a modified Koster interferometer for fringe generation, and fast detector arrays for light detection and integration. The image space-bandwidth-product and dynamic range are enhanced by processing time-multiplexed interlaced image subpatches at real-time rates. Digital pre- and post-processing play essential roles in the system enhancement. The final image is a mosaic of the subpatch images. The optical processor design approach lends itself to the important attributes of high (real-time) data rates, multiple SAR mode processing capabilities, compact and rugged packaging, and power efficiency.
Progress toward a flight demonstration of the acousto-optic time- and space- integrating real-time SAR image formation processor program is reported. The concept overcomes the size and power consumption limitations of electronic approaches by using compact, rugged, and low-power analog optical signal processing techniques for the most computationally taxing portions of the SAR imaging problem. Flexibility and performance are maintained by the use of digital electronics for the critical low-complexity filter generation and output image processing functions. The results reported include tests of a laboratory version of the concept, a description of the compact optical design that will be implemented, and an overview of the electronic interface and controller modules of the flight-test system.
In order to achieve a wideband and wide-angle electronically scanned antenna, Hughes has been working under an ARPA/Rome Lab Program to develop an L-band 96-element phased array antenna that incorporates fiber optic remoting of RF and digital control signals as well as a true-time delay beam steering mechanism. The true-time delay is accomplished by a combination of fiber optic and microwave stripline programmable delays.
After reviewing the function of a Multiple Sidelobe Canceler in a typical radar application and providing an overview of the goals and architecture of the Acousto-Optic Null Steering Processor program, this paper describes the hardware configuration of the breadboard model and reports the performance of this system to date. Significant design issues and experimental observations are discussed. Some of these design issues have been discovered during breadboard evaluation; others were predicted by simulation and have been verified experimentally. This paper concludes by identifying those areas where the greatest potential for performance improvement lies.
The development of low-loss, low-cost integrated optical switches is critical for radar phase control applications. We report recent progress in integrated phosphorous-doped SiO2 on Si (PSG) waveguide optical routing switches based on electro-static actuation of an aluminum membrane. We have demonstrated the membrane switching concept and its implementation feasibility with a Mach-Zehnder interferometer and a deposited aluminum thin film. Without the metal film, 95% of the output light was measured in the cross channel, with a channel crosstalk of -13.37 dB. With a 3 mm long aluminum film being deposited on one of the interferometer arms as a phase shifter, 94% of the output light was measured in bar channel. The switch structure is currently being optimized for better performance, and a deformable aluminum membrane switch is being developed.