ROME LABORATORY'S DRAFT FY98 SBIR TOPICS PART 4 OF 10. ROME LABORATORY'S DRAFT FY 98 SBIR TOPICS. ROME LABORATORY IS PLEASED TO MAKE AVAILABLE THE FOLLOWING DRAFT SMALL BUSINESS INNOVATIVE RESEARCH (SBIR) PROGRAM TOPICS. THESE TOPICS ARE NOT APPROVED AS YET AND ALL MAY NOT APPEAR IN THE FINAL SOLICITATION: SBIR TOPIC #AF98-119. TECHNICAL POINT OF CONTACT: Dr. Jeffrey S. Herd, RL/ERAA (617) 377-4214. TITLE: Digital Beamforming Development. CATEGORY: Applied Research. DOD CRITICAL TECHNOLOGY AREA: B07. SERVICE CRITICAL TECHNOLOGY AREA: AF1. OBJECTIVE: Develop architecture(s), appropriate algorithms, and implementation concepts for a satellite payload that utilizes digital beamforming on receive and/or transmit. DESCRIPTION: Phased array or multiple beam antennas use beam forming networks to (1) form a desired radiation pattern, and/or (2) generate multiple beams from the same aperture. If a large number of beams or maximum flexibility is required, an all-digital implementation of this beam forming network is worthy of consideration. This requires, however, that the received signals from an array of antenna elements are individually pre-amplified, frequency down-converted, digitized, and then fed into a digital processor, where beam forming and other functions, such as channelizing (demultiplexing and filtering), are performed. Similarly, on transmit, the array must digitally combine multiple beam signals, D/A convert, frequency up-convert and linearly amplify each channel. Multiple agile beams (perhaps in the hundreds) could be simultaneously formed in the digital processor. Each beam could be specially contoured and directed to satisfy a specific regional coverage requirement. Sidelobes could be lowered to permit frequency reuse operation, or even to mitigate RF interference from non-users. Each of these capabilities could be implemented with either fixed algorithms, or algorithms having adaptive features. The digital processor architecture should also permit channel and beam assignments to be made with full flexibility. The key performance issuesare the availability of enough dynamic range and bandwidth in the A/D converters and the capacity and speed of the digital processor. The viability of digital versus analog beamforming depends not only on performance, but ultimately on the relative impacts on payload size, weight, and especially power. A beam-forming test bed should also be developed along with the digital processor prototype. Proposals that address innovative A/D Converter and high speed Digital Signal Processor designs will also be considered. PHASE I: Investigate candidate digital beamforming/channelizing architectures, and develop top level functional descriptions of the selected architecture(s). Assess the status of component technology, particularly A/D Converter and Digital Signal Processors technology, and develop a prototype design and performance specifications(s) for a proposed digital processor. Provide proof of concept documentation and/or simulation of the proposed design(s). PHASE II: Develop the appropriate beamforming and other algorithms for the selected architecture(s). Perform tradeoffs and analyses to evaluate and develop an implementation approach to the architecture(s) selected in Phase I. Develop a computer model of the proposed digital processor to assess and demonstrate performance. Develop a prototype processor and demonstrate key performance characteristics through an appropriate test-bed. PHASE III DUAL USE APPLICATIONS: Both military and commercial systems would benefit from the flexibility of digital beamforming/ channelization, even though the emphasis and resultant architectures would likely be different. Commercial systems are usually interested in deploying a large number of beams and in frequency reuse. Future military systems, on the other hand, must consider robustness and consequently high dynamic range as a critical requirement, but will also employ frequency reuse to meet growing requirements for high capacity. KEYWORDS: Antennas, Satellite Payload, Beamforming, Digital Receive, Beamforming Network, A/D Converte. SBIR TOPIC #AF98-120. TECHNICAL POINT OF CONTACT: Richard N. Smith, RL/C3BA (315) 330-7436. TITLE: Digitally Adaptive Nulling Algorithm Development. CATEGORY: Applied Research. DOD CRITICAL TECHNOLOGY AREA: B07. SERVICE CRITICAL TECHNOLOGY AREA: AF1. OBJECTIVE: Develop adaptive nulling algorithms for an all-digital adaptive nulling processor. DESCRIPTION: Adaptive nulling can be used on a communication satellite system to protect against uplink jamming. This technique involves modifying the receive antenna pattern such that a pattern null is placed in the direction of the jammer. Furthermore, it must be adaptive because the location of the jammer and its operational strategy would not be known a priori. Current nulling systems, such as in Milstar II, employ basically a single fixed algorithm, implemented in a hybrid analog/digital processor. Considerably more flexibility could be achieved with an all-digital processor. Multiple algorithms could be implemented specifically to make the nuller more immune to intelligent jamming. Algorithms with additional constraints to achieve, for example, better pattern coverage for users might also be implementable in an all-digital processor. New algorithms could even be uploaded to enhance nulling performance during the operational lifetime of the satellite. Many of these algorithms have already been studied in the literature. The key issues are how to implement an overall architecture and the amount of processing capacity and speed that can be made available under reasonable constraints on weight and power. PHASE I: Investigate and/or develop adaptive nulling algorithms for on-board, all-digital processing application. Develop an overall architecture for a multiple-algorithm, all-digital processor. Develop simulation tools and demonstrate key performance. PHASE II: Assess the status of digital processing component technology, and determine the feasibility of implementing the digital architecture developed in Phase I. Generate estimates of hardware size, weight, and power. Perform analysis and simulation to assess nulling performance, particularly to evaluate the response time against various types of jammers. The contractor should also include performance demonstrations of adaptive nulling that is relevant to the commercial space craft world. PHASE III DUAL USE APPLICATIONS: Commercial systems encounter RF interference from unintentional sources. These instances are increasing due to the limited communications spectrum being shared by a growing number of communication systems. Through the use of adaptive nulling, commercial systems will have the ability to maintain performance. KEYWORDS: Communications Satellite, Receive Antenna, Adaptive Nulling, Uplink Jamming, Nulling Algorithms, All Digital Processor. SBIR TOPIC #AF98-121. TECHNICAL POINT OF CONTACT: Gregory J. Hadynski, RL/C3BA (315) 330-4094. TITLE: EHF/SHF/Ka Communications Link Attenuation and Availability Model. CATEGORY: Applied Research. DOD CRITICAL TECHNOLOGY AREA: B0. SERVICE CRITICAL TECHNOLOGY AREA: AF1. OBJECTIVE: Develop a computer model for predicting satellite communications link attenuation and availability at EHF/SHF/Ka frequencies. DESCRIPTION: Atmospheric propagation effects can significantly impair the performance of satellite communications links operating at the EHF/SHF/Ka frequencies. Existing propagation models, primarily due to shortcomings in the weather and attenuation measurement database do not provide a satisfactory framework for estimating link performance and often give conflicting results. There are also significant shortcomings in the environmental databases that support these models, especially the lack of instantaneous rainfall rate and frequency of occurrence data for more than a small number of selected locations. The recent availability of EHF/SHF/Ka satellite link attenuation data from the NASA ACTS satellite and other sources may now facilitate the development of a comprehensive model of link attenuation/availability that will better address the needs of a worldwide EHF/SHF/Ka satellite communication system. PHASE I: In Phase I, the structure of a link attenuation/ availability model and environmental database shall be developed, based on Air Force input together with an analysis of existing models and expanded data sources. Sources of data to be used to calibrate and verify the model shall be identified. Proof of concept documentation and/or simulation shall be provided as a basis for Phase II feasibility. A comprehensive plan for Phase II shall be prepared. PHASE II: The Phase II effort shall include three tasks: 1) Finalize Link Attenuation/Availability Model Development. The model shall accurately calculate attenuation (dB loss) and availability (percentage of time) for a bi-directional communications link between a ground terminal and a satellite as a function of carrier frequency, elevation angle, and terminal environment (temperature, humidity, rain rate, cloud cover, fog, altitude, etc.). The model must be tailored to meet limitations imposed by the available environmental data. The model should focus on the 44 GHz/21 GHz uplink/downlink Milsatcom frequencies, but should also be applicable to EHF/SHF/Ka frequencies used and proposed by commercial systems. The model development effort should build on the existing body of knowledge and inventory of models by recalibrating to the recently available data. 2) Environmental Database Development: a global database of weather data specifically tailored to the format of the model shall be developed. 3) Computer Program Development: The link attenuation/availability model and the environmental database will be combined into a single user-friendly computer program tailored to the task of analyzing EHF/SHF/Ka link performance. The program will generate color-coded maps depicting link attenuation or availability on a global or regional scale, contours of constant link attenuation or availability, or point estimates for specific locations (with an option for the user to input site-specific environmental data). The program will generate availability for a link with a specified margin, or will generate the margin required to achieve a specified availability. The results will be an annual average or season specific. All outputs will reflect the orbital motion of a specified satellite constellation. PHASE III DUAL USE APPLICATIONS: The model will be inherently applicable to both military and commercial communications systems operating at EHF/SHF/Ka frequencies. Using this model, commercial satellite developers will be able to accurately predict the required power levels of their transponders. KEYWORDS: Satellite Communications, EHF/SHF/Ka, Link Availability, Link Attenuation, Link Margin, Atmospheric Attenuation, Radio Propagation. Margot Ashcroft, SBIR Program Manager, RL/XPD, 315-330-1793, Joetta A. Bernhard, Contracting Officer, RL/PKPX, 315-330-2308.

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