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 Applications of Adaptive Systems to Communications, Navigation, and Surveillance R. Davis, R. Fante, K. Mauck, B. Rama Rao, P. Sanyal, J. Torres, J. Vaccaro, J. Williams Communications: Interference Mitigation for IS-95 CDMA Mobiles MITRE is developing a custom military applique´ that interfaces with commercial wireless equipment and performs adaptive interference navigation. The commercial equipment consists of a mobile handset that operates in the cellular band using the IS-95 CDMA digital standard. The applique´ consists of several antennas, RF and digital hardware and real-time software, and interfaces with the mobile only through the handset antenna. The interference is cancelled using a robust, adaptive space-time signal processing algorithm that requires no prior knowledge either of the receive array geometry or the characteristics of the interference. This processor provides up to 40 dB of jammer rejection.
Airborne Surveillance: Adaptive Bistatic Radar It is expected that the global surveillance function will migrate to space, with transmitters mounted on geostationary or medium-earth-orbit satellites and receivers on low-earth-orbit satellites or UAVs. While these radars can detect fast-moving targets immersed in ground clutter using conventional approaches, it is found that space-time adaptive processing is required to detect either slowly-moving ground targets or low radar-cross-section airborne targets. Using simulations, MITRE has demonstrated that it is possible to detect ground targets moving as slowly as 1 meter per second using an adaptive, bistatic, space-based radar.
Ground-Based Surveillance Ground based surveillance radars must detect and locate targets even in the presence of escort jammers. MITRE has developed an approach that uses the outputs only from the antenna subarrays to simultaneously cancel mainbeam jammers and detect and locate targets. The algorithm combines adaptive spatial processing of the subarray outputs (to cancel jammers) with a maximum likelihood estimator of target location. Simulations indicate that even in the presence of a mainbeam jammer the target can be detected and located to within one-third of a beamwidth. For more information, please contact Ronald Fante using the employee directory. |
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