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Rubin S.H.,SPAWAR SSC Pacific | Lee G.,San Diego State University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

The solution for insuring the safety of tele-operated or fully unmanned autonomous systems (UASs) in the air space requires a) that the human remain in and on the loop to the maximal extent practical and b) that the UASs, which share the air space, have an intelligent backend for the processing of their sensory data. Moreover, it is necessary that this sensory processor be capable of generalizing and learning more than it was told in order that it properly handle situations not explicitly programmed for. Given the advent of advances in nanotechnology and microsystems, several research teams continue to investigate the integration of such technologies for single UASs and small swarms of UASs for military, commercial, and civilian applications. Our proposed technology can be readily adapted for transparent learning to serve as an assistant for human piloting as well as an emergency intelligent autopilot for all manner of piloted vehicles. © 2011 Springer-Verlag. Source


Ma N.N.,Johns Hopkins University | Buchanan K.,SPAWAR SSC Pacific | Jensen J.,Texas A&M University | Huff G.,Texas A&M University
Proceedings - IEEE Military Communications Conference MILCOM | Year: 2015

Today's wireless systems often require dynamic radiation characteristics such as high directivity, wide steerability, and large bandwidth, which are usually not achievable by single antenna frontends. Phased array technology offers a solution by combining multiple elements together in such a way that their radiation characteristics constructively interfere. Typically, the antenna elements are distributed periodically over lattice grids; however, this can lead to undesirable effects such as scan blindness and surface wave propagation. Instead, randomly distributing the radiators can attain the same performance increases without suffering from the detrimental effects of periodic structures. This work provides an analysis of the array behavior for planar triangular randomly distributed antenna arrays (TRA). A probabilistic theory is presented followed by numerical experiments from both the array factor analysis and Ansys HFSS finite-element simulations. Measurements of a prototype array system show main beam scanning capabilities. © 2015 IEEE. Source


Rodriguez D.,SPAWAR SSC Pacific | Lumdsen N.,SPAWAR SSC Pacific | Hansen P.,Long Wave Inc. | Lukes L.,George Mason University | And 4 more authors.
2016 United States National Committee of URSI National Radio Science Meeting, USNC-URSI NRSM 2016 | Year: 2016

There remains significant interest in understanding the spatial and temporal effects ionosphere disturbances have on radio wave propagation. In particular, RF propagation in the low frequency bands from 30 to 300 kHz is susceptible to ionospheric variations caused by volcanic and seismic activity as well as ionosolar eclipses. These variations modify the Earth-Ionosphere waveguide resulting in changes to the amplitude and phase difference along different transmission paths. The goal of this paper is to determine the feasibility of using an existing LF transmitter to support ionosphere-radio wave propagation studies in the future. © 2016 IEEE. Source


Berggren S.,San Diego State University | Prokopenko G.,Hypres Inc. | Longhini P.,SPAWAR SSC Pacific | Palacios A.,San Diego State University | And 10 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2013

We develop a two-dimensional (2-D) superconducting quantum interference filter (SQIF) array based on the recently introduced high-linearity tri-junction bi-SQUIDs (superconducting quantum interference device). Our bi-SQUID SQIF array design is based on a tight integration of individual bi-SQUID cells sharing inductances with adjacent cells. We provide extensive computer simulations, analysis, and experimental measurements, in which we explore the phase dynamics and linearity of the array voltage response. The nonuniformity in inductances of the bi-SQUIDs produces a pronounced zero-field single antipeak in the voltage response. The antipeak linearity and size can be optimized by varying the critical current of the additional junction of each bi-SQUID. The layout implementation of the tight 2-D array integration leads to a distinct geometrical diamond shape formed by the merged dual bi-SQUID cells. Different-sized 2-D arrays are fabricated using the standard HYPRES niobium 4.5 kA/cm2 fabrication process. The measured linearity, power gain, and noise properties will be analyzed for different array sizes and the results will be compared with circuit simulations. We will discuss a design approach for the electrically small magnetic field antenna and low-noise amplifiers with high bandwidth based on these 2-D bi-SQUID SQIF arrays. The results from this work will be used to design chips densely and completely covered in bi-SQUIDs that have optimized parameters such as linearity and power gain. © 2012 IEEE. Source


Hansen P.,URS Corporation | Acevedo V.,SPAWAR SSC Pacific | Kagan J.,SPAWAR SSC Pacific | Goebel W.,SPAWAR SSC Pacific | And 2 more authors.
IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) | Year: 2015

This paper discusses a method to radiate high-power VLF signals from terrestrial based transmitters to the ionosphere. Validation of modeling results are presented for a half-wave dipole scale model antenna and results of 11 separate soil conductivity measurements performed at the site of the antenna. Results from this paper can be used to determine the efficiency and maximum radiated power for a full scale horizontal dipole antenna operating below 20 kHz. © 2015 IEEE. Source

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