Time filter

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Fairfax, VA, United States

Hawkinson W.,Honeywell | Samanant P.,Honeywell | McCroskey R.,Honeywell | Ingvalson R.,Honeywell | And 3 more authors.
Record - IEEE PLANS, Position Location and Navigation Symposium | Year: 2012

A system that provides accurate and reliable location of Emergency Responders (ERs) in all types of environments presents multifaceted technological challenges. The system is intended to provide indoor/outdoor precision navigation, robust communications and real-time position updates on remote command display devices. Operational requirements include rapid and nonintrusive deployment, scalability to 500 users and seamless integration with existing procedures. Additional challenges are imposed by the need for a device that minimizes size, weight, and power with the ability to operate in uncertain and potentially hazardous in-building environments. © 2012 IEEE.

Draganov A.,Argon ST
26th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GNSS 2013 | Year: 2013

The Predictor-Corrector Unscented Kalman filter is designed to compute the measurement update for linear or nonlinear measurements. It is backward-compatible with other Kalman filter formulations (e.g., EKF or UKF) in a sense that the filter state is described by the mean and covariance only. At a small additional cost in computational load, this filter delivers a better (sometimes, much better) accuracy than alternatives.

Bailey M.C.,Applied EM Inc. | Campbell T.G.,Applied EM Inc. | Reddy C.J.,Applied EM Inc. | Kellogg R.L.,Argon ST | Nguyen P.,U.S. Navy
IEEE Antennas and Propagation Magazine | Year: 2012

In this paper, we describe a compact, wideband (70-3000 MHz), and high-gain antenna technology that can replace multiple types of antennas currently in use to cover the wide frequency band. The design eliminates the frequency-band breaks associated with the use of multiple arrays. The wideband direction-finding array (with a height of 5.5 in and a diameter of 15.5 in) is the result of end-to-end integration of the antenna array with the receivers presently used, or to be used, on platforms of interest. Development of the wide-bandwidth direction-finding antenna array is described, and computer simulations of its performance are presented. The wideband direction-finding antenna system has been verified on the receiver manufacturer's outdoor test range. © 2011 IEEE.

Haas L.,Argon ST | Harlacher M.,Argon ST
Record - IEEE PLANS, Position Location and Navigation Symposium | Year: 2010

The Synthetic Aperture Navigation (SAN) signal processing algorithm identifies the desired line of sight (LOS) signal component by exploiting user motion. As implied by the name, it forms a synthetic aperture along the user trajectory by taking multiple snapshots of signal correlation with the replica waveform over some period of time as the user moves. The synthetic aperture serves as an array, which enables beamforming with a single-element antenna. Fundamentally, this method discriminates between different signal components (e.g., line of sight and multipath) by their directions of arrival. SAN places the antenna array gain on the desired signal component and places nulls on all other components. This operation is applied to data from all correlators in the receiver, thus effectively providing the receiver discriminator with nearly multipath-free measurements. SAN is even able to produce a quality line of sight (LOS) measurement when the LOS component is much weaker than multipath. ©2010 IEEE.

Perloff M.,SSCI | Krishnan R.,Argon ST | Ramanathan R.,BBN | Gutierrez C.,SSCI | And 3 more authors.
Proceedings - IEEE Military Communications Conference MILCOM | Year: 2011

As evolving operational requirements compel forces to deploy sparsely there is a need to extend tactical network protocols to operate in the Disruption-Tolerant Networking (DTN) regime, in which frequent disconnections are the norm. In airborne networks 1, connectivity may be temporarily lost when aircraft use different paths to avoid terrain or other obstacles or to perform assigned tasks. In sensor networks, nodes may become disconnected due to environmental conditions or power management, but the set of proximal nodes may not change much over time, despite the intermittent connections. These scenarios challenge standard link-state approaches, both in terms of the protocol overhead and the ability to maintain awareness of all network nodes. Routing protocols designed for the DTN regime, however, cause extreme packet replication to cover the most general conditions conceivable, making them impractical in realistic scenarios. We propose modifications to a widely used link-state protocol, OSPF, to deal with significantly more disruptions to connectivity while retaining the efficiencies of the shortest path approach. We describe simple changes that enable OSPF to find routes through a stable set of neighbors that are only intermittently available. Our use of OSPF minimizes changes and implementation costs, and takes advantage of reliable, proven methods for network state information delivery. We have implemented DTN-extended OSPF within the quagga IP routing framework. Our simulation tests show that, with our modifications, OSPF maintains a global view of the entire network, including both reachable and unreachable nodes, so that messages can be held and routed to temporarily unavailable nodes. Using simulations as well as real packet traffic over an emulated network, we compare DTN-extended OSPF with standard OSPF, and we show that our methods permit messages to be delivered to remote nodes in cases where standard OSPF would discard most or all packets. We conclude by outlining additional methods to reduce DTN overhead traffic and increase DTN-extended OSPF's reliability. © 2011 IEEE.

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