A full wave method for rough surface scattering using fictitious current distributions

Rough surface scattering is a current topic of interest in many diverse fields. But, despite its importance, the two most widely used solution methods, the Kirchhoff and first order perturbation methods, are valid only for a restricted range of surface types. There is a large range of surface statistics for which neither of these theories is valid. There are purely numerical solutions to the problem, i.e., the integral equation technique and FDTD method, but these methods require a prohibitively large amount of computer time and storage space for use in practical applications. A full wave method has been introduced by E. Bahar which agrees with the Kirchhoff method in its range of validity, but does not bridge the gap between the later two standard theories and does not provide understanding of the physical processes involved in rough surface scattering. Consequently, it has been a center of controversy since modifications made to improve the method seem arbitrary and are without mathematical or physical justification. The method presented here is a new full wave method which uses equivalent currents to provide insight into the physical scattering processes. This full wave method analytically reduces to the two standard theories in their respective regions of validity and bridges the gap between the two, which was shown by comparison to the integral equation method. The results presented here are for statistically rough surfaces with Gaussian distributed heights and slopes. A Monte Carlo procedure is used to generate the radar cross section data for this new full wave method

Briefing Two: Justice for All and the Economic Crisis

The world faces its biggest economic crisis in almost 100 years. COVID-19's economic impacts are sure to last longer than the public health emergency and will trigger a massive increase in justice problems. Unemployment is rising, people are increasingly threatened by eviction, many companies are fighting to stave off bankruptcy. In our briefing on Justice for All and the Economic Crisis we present strategies for how justice systems can help, not hinder economic recovery, and how justice leaders can take action to reshape justice systems and support more inclusive, sustainable, and resilient patterns of growth.This report was commisioned by Pathfinders for Peaceful, Just and Inclusive Societie

LTE SYSTEM ARCHITECTURE FOR COVERAGE AND DOPPLER REDUCTION IN RANGE TELEMETRY

A novel approach employing 4G LTE Cellular Technology for Test Range Telemetry is presented. Providing aeronautical mobile telemetry using commercial off the shelf (COTS) cellular equipment poses many challenges, including: Three-dimensional (3D) coverage, need for uninterrupted high data throughputs, and very high Doppler speeds of the Test Articles (TA). Each of these requirements is difficult to meet with a standard cellular approach. We present a novel architecture that provides 3D coverage over the span of a test range, allowing the TA to establish a radio link with base stations that have a manageable Doppler due to the reduced projected TA speed on the radio link line. Preliminary results illustrate that a variety of flight plans can be accommodated with commercial LTE technology by employing LTE’s mobility mechanisms and adding centralized control. The resulting network architecture and Radio Access Network topology allow very high throughputs to be delivered throughout the test range with a judicious placement of base stations.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

COMPREHENSIVE SPECTRUM MONITORING SYSTEM (COSMOS) FOR NEXT-GENERATION SPECTRUM SITUATIONAL AWARENESS

Comprehensive Spectrum Monitoring System (COSMOS) is Perspecta Labs’ solution for Next-Generation Spectrum Situational Awareness (NGS2AS), a Spectrum Access R&D Program solicited and awarded through the National Spectrum Consortium. COSMOS will incorporate a mix of low-cost unattended RF sensors, networked using industry-standard interfaces; versatile back-end server processing and storage of sensor data; spectrum data analytics, reporting and visualization; and incorporation of historical and projected frequency usage data from DoD systems for planning of training and test missions. This paper describes the architecture and design of the COSMOS system and its sensor and server subsystems.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

RF Planning for 3D coverage in Cellular LTE Range Telemetry

Initial analysis and lab experiments have provided positive confirmation of the viability of 4G LTE Cellular Technology for Aeronautical mobile telemetry. COTS LTE equipment is deployed for the test range frequency bands. The high speeds of test articles (TAs) can be addressed with a UE add-on applique’ customized to compensate for the Doppler shifts. The applique has worked effectively with the LTE physical layer. To achieve spectrum efficiency, a multi-cell network is planned. Mobility is managed with native LTE handovers. To address extreme Doppler cases, additional support is provided to mobility management via a central entity that estimates the TA’s trajectory and issues handover commands. Within this framework, we present aspects of an RF planning study that characterizes the dependence of coverage on such design parameters as base station density, antenna orientation, and altitude of the user device. We also quantify the Doppler shifts that can result under the standard strategy of connecting the user device to the strongest cell, and show how, with an alternative, threshold-based strategy, one can achieve a substantial reduction in Doppler shifts at the expense of a loss in user rates.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

A Spectrum Management Tool to Aid Efficient Frequency Assignments at Test Ranges

ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, CaliforniaIncreasing demands for telemetry bandwidth in conjunction with commercial encroachments on telemetry spectrum have created a need for test range operations personnel to make frequency assignments in the most efficient manner possible. The Spectrum Management System (SMS) project researches a potential tool to bring advanced capabilities to the assistance of test range operations. Features that appear to have significant utility are: frequency assignment optimizations to simultaneously satisfy device and spectrum constraints, prediction of RF channel quality across airspace, and support for frequency reuse. A prototype system is currently being trialed at selected test ranges.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Cellular 4G LTE Aeronautical Mobile Telemetry Flight Test Results

Flight test results on an Aeronautical Mobile Telemetry (AMT) system employing 4G Long Term Evolution (LTE) Cellular Technology are presented. The AMT system comprises a ground network of Commercial Off-The-Shelf (COTS) cellular base stations. Very high Doppler shifts due to the high speed of the Test Article (TA) are handled by an appliqué front-end to a COTS mobile transceiver. Doppler compensation allows seamless operation of LTE as the TA traverses the coverage area. An uninterrupted radio link as well as high bi-directional data rates were achieved even at a distance of 60 Km between the base stations and the TA. The results clearly demonstrate that the system can sustain an uninterrupted LTE connection at Doppler shifts that are much higher than what typical commercial LTE systems can support. The 4G system featured in this exercise has a direct extension to 5G technologies.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit https://telemetry.org/contact-us/ if you have questions about items in this collection

LTE-BASED AERONAUTICAL MOBILE TELEMETRY - LAB AND FIELD TEST EXPERIMENTS

Aeronautical mobile telemetry (AMT) based on 3GPP’s LTE standard is implemented in a proof-of-concept system. The solution tackles the very high Doppler shifts expected in flight tests using an appliqué that can be inserted between the transmit/receive ports of the Test Article (TA) and the antennas. This appliqué estimates the Doppler shift and proactively compensates for it on the uplink signal being transmitted by the TA. The overall system has been tested under different operational conditions in a laboratory setup as well as in the field. In the laboratory setup, the desired operating conditions are created with a set of Software-Defined-Radio-based channel emulators coupled with a computer to control their behavior. In order to carry out field tests, an operational LTE network has been created at Edwards Air Force Base (EAFB) with two base stations, backhaul links, and a core network. In this paper, we provide descriptions of both laboratory and field test setups as well as the results of several tests that have been carried out to date. The results of lab and field tests lend strong support to the viability of this AMT solution.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Clinical Applications of Electrical Stimulation After Spinal Cord Injury

During the last one-half century, electrical stimulation has become dinically significant for improving health and restoring useful function afterspinal cord injury. Short-term stimulation can be provided by electrodes on the skin or percutaneous fine wires, but implanted systems are preferable for long-term use. Electrical stimulation of intact lower motor neurons can exercise paralyzed musdes and reverse wasting; improve strength, endurance, and cardiovascular fitness; and may reduce the progression of osteoporosis. Other potential therapeutic uses being investigated indude reduction of spasticity, prevention of deep vein thrombosis, and improvement of tissue health. Pacing of intact phrenic nerves in high tetraplegia can produce effective respiration without mechanical ventilation, allowing improved speech, increased mobility, and increased sense of well-being. lmprovement of cough has also been demonstrated. Stimulation of intact sacral ne.rves can produce effective micturition and reduce urinary tract infection; it can also improve bowel function and erection. lt is usually combined with posterior sacral rhizotomy to improve continence and bladder capacity, and the combination has been shown to reduce costs of care. Electroejaculation can now produce semen in most men with spinal cord injury. Significant achievements have also been made in restoring limb function . Useful hand grasp can be provided in CS and C6 tetraplegia, reducing dependence on adapted equipment and assistants. Standing, assistance with transfers, and walking for short distances can be provided to selected persons with paraplegia, improving their access to objects, places, and opportunities that are inaccessible from a wheelchair. This review summarizes the current state of therapeutic and neuroprosthetic applications of electrical stimulation afterspinal cord injury and identifies some future directions of research and dinical and commercial development