Systems and Communications Commons^™

Propagation Effects Handbook For Satellite Systems Design, Louis J. Ippolito

Online Journal of Space Communication

This paper describes the latest edition of the NASA Propagation Effects Handbook for Satellite Systems Design and presents a summary of application of the handbook information to satellite link design and performance. NASA, which has supported a large part of the experimental work in radiowave propagation on space communications links, recognized the need for a reference handbook of this type, and initiated a program in the late 1970's to develop and update a document that will meet this need. The Fifth Edition provides, in a single document, an update to two previous NASA handbooks; the fourth edition of a handbook …

Special Effects: Antenna Wetting, Short Distance Diversity And Depolarization, Roberto J. Acosta

Online Journal of Space Communication

The Advanced Communication Technology Satellite (ACTS) communications system operates in the Ka frequency band. ACTS uses multiple, hopping, narrow beams and very small aperture terminal (VSAT) technology to establish a system availability of 99.5% for bit-error-rates of 5x 10-7 or better over the continental United States. In order maintain this minimum system availability in all US rain zones, ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of system and sub-system characterizations considering the statistical effects of system variances due …

Ka-Band System And Propagation Effects On System Performance, Roberto J. Acosta, Sandra Johnson

Online Journal of Space Communication

The Advanced Communication Technology Satellite (ACTS) is an experimental communications satellite system launched in September 1993. ACTS introduces many new technologies, including operation in the Ka frequency band. ACTS uses multiple hopping narrow beams and very small aperture terminal (VSAT) technology to establish a system availability of 99.5% for a bit-error-rates of 5x10-7 or better over the continental United States. In order to maintain a minimum system availability f 99.5% over all US rain zones ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is …

Comparison Of Multiple Rain Attenuation Models With Three Years Of Ka Band Propagation Data Concurrently Taken At Eight Different Locations, Glenn S. Feldhake, Lynn Ailes-Sengers

Online Journal of Space Communication

In June 1996, Working Party 3M of the ITU-R presented research comparing the estimations of 10 rain attenuation models with the 186 station years of earth-space propagation data contained within the ITU-R database known as DBSG5. Now, twenty-one station years of new data taken exclusively in the Ka band (20.185 GHz and 27.505 GHz) across North America are measured against many of those same models. Results are presented both in terms of error statistics as well as in comparison to the ITU database results.

Rain Attenuation Model Comparison And Validation, Charles E. Mayer, Bradley E. Jaeger

Online Journal of Space Communication

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Ka-Band Propagation Modeling For Fixed Satellite Applications, Asoka Dissanayake

Online Journal of Space Communication

Propagation impairments produced by the troposphere are a limiting factor for the effective use of the 20/30 GHz frequency band. Use of smaller earth terminals, while very attractive for consumer and transportable applications, make it difficult to provide sufficient link margin for propagation related outages. In this context, reliable prediction of propagation impairments for low-availability systems becomes important. This paper addresses the issues related to predicting different types of propagation impairments as well as combining them together to determine the overall impact on satellite links over a wide range of outage probabilities.

A Prediction Model That Combines Rain Attenuation And Other Propagation Impairments Along Earth-Satellite Paths, Asoka Dissanayake, Jeremy Allnutt, Fatim Haidara

Online Journal of Space Communication

The rapid growth of satellite services using higher frequency bands such as the Ka-band has highlighted a need for estimating the combined effect of different propagation impairments. Many projected Ka-band services will use very small terminals and, for some, rain effects may only form a relatively small part of the total propagation link margin. It is therefore necessary to identify and predict the overall impact of every significant attenuating effect along any given path.

A procedure for predicting the combined effect of rain attenuation and several other propagation impairments along earth-satellite paths is presented. Where accurate models exist for some …

Acts Propagation Experiment: Experiment Design, Calibration, And Data Preparation And Archival, Robert K. Crane, Xuhe Wang, D. B. Westenhaver, Wolfhard J. Vogel

Online Journal of Space Communication

The National Aeronautics and Space Administration Advanced Communications Technology Satellite (ACTS) propagation experiment was designed to obtain slant-path attenuation statistics for locations within the United States and Canada for use in the design of low-margin Ka-band satellite communication systems. Experimenters at seven different locations have collected propagation data for more than two years. The propagation terminals used for the experiment were identical. A single preprocessing program was used by the experimenters to provide for automatic calibration, generation of attenuation histograms, and data archival. In this paper, the calibration procedures are described and estimates given for measurement accuracy.

ACTS provided beacons …

Ka-Band Propagation Measurements: An Opportunity With The Advanced Communications Technology Satellite (Acts), Robert Bauer

Online Journal of Space Communication

The Advanced Communications Technology Satellite (ACTS) was conceived at the National Aeronautics and Space Administration (NASA) as a follow-on program to its long history in satellite communications projects that have reduced the risk of developing new technologies that fall outside the sponsorship capability of the private sector.

To counter the foreign challenge that developed in the late 1970's to the once insuperable U.S. lead in this field, ACTS was developed to maintain the U.S. preeminence. Launched in September 1993 from the space shuttle, key technologies on ACTS include a multibeam antenna, a baseband processor, a 900-MHz wideband microwave switch matrix, …

Advanced Communications Technology Satellite (Acts): Design And On-Orbit Performance Measurements, Frank Gargione, R. Acosta, T. Coney, R. Krawczyk

Online Journal of Space Communication

The Advanced Communications Technology Satellite (ACTS), developed and built by Lockheed Martin Astro Space for the NASA Lewis Research Center, was launched in September 1993 on the Shuttle STS 51 mission. ACTS is a digital experimental communications test bed that incorporates gigahertz bandwidth transponders operating at Ka band, hopping spot beams, on-board storage and switching, and dynamic rain fade compensation. This paper describes the ACTS enabling technologies, the design of the communications payload, the constraints imposed on the spacecraft bus, and the measurements conducted to verify the performance of the system in orbit.

Historical Development: Acts Technology, Richard Gedney, Ron Schertler, Frank Gargione

Online Journal of Space Communication

The following material has been extracted from "The Advanced Communications Technology Satellite" book by Richard Gedney, Ron Schertler and Frank Gargione.

Issue 2: From The Guest Editor, Frank Gargione

Online Journal of Space Communication

Guest editor introduction

Historical Development: Acts Program Formulation, Richard Gedney, Ron Schertler, Frank Gargione

Online Journal of Space Communication

The following material has been extracted from "The Advanced Communications Technology Satellite" book by Richard Gedney, Ron Schertler and Frank Gargione.

Multilayer Perceptron With Auto Encoder Enabled Deep Learning Model For Recommender Systems, Subhashini Narayan

Future Computing and Informatics Journal

In this modern world of ever-increasing one-click purchases, movie bookings, music, health- care, fashion, the need for recommendations have increased the more. Google, Netflix, Spotify, Amazon and other tech giants use recommendations to customize and tailor their search engines to suit the user’s interests. Many of the existing systems are based on older algorithms which although have decent accuracies, require large training and testing datasets and with the emergence of deep learning, the accuracy of algorithms has further improved, and error rates have reduced due to the use of multiple layers. The need for large datasets has declined as well. …

Context-Aware Sensing And Fusion For Structural Health Monitoring And Night Time Traffic Surveillance, Xinxiang Zhang

Electrical Engineering Theses and Dissertations

Rapid developments in computer vision technologies have been transforming many traditional fields in engineering and science in the last few decades, especially in terms of diagnosing problems from visual images. Leveraging computer vision technologies to inspect, monitor, assess infrastructure conditions, and analyze traffic dynamics, has gained significant increase in both effectiveness and efficiency, compared to the cost of traditional instrumentation arrays to monitor, and manually inspect civil infrastructures and traffic conditions. Therefore, to construct the next-generation intelligent civil and transportation infrastructures, this dissertation develops a comprehensive computer-vision based sensing and fusion framework for structural health monitoring and intelligent transportation systems. …

Class-Incremental Learning For Wireless Device Identification In Iot, Yongxin Liu, Jian Wang, Jianqiang Li, Shuteng Niu, Houbing Song

Publications

Deep Learning (DL) has been utilized pervasively in the Internet of Things (IoT). One typical application of DL in IoT is device identification from wireless signals, namely Noncryptographic Device Identification (NDI). However, learning components in NDI systems have to evolve to adapt to operational variations, such a paradigm is termed as Incremental Learning (IL). Various IL algorithms have been proposed and many of them require dedicated space to store the increasing amount of historical data, and therefore, they are not suitable for IoT or mobile applications. However, conventional IL schemes can not provide satisfying performance when historical data are not …

Data Forgery Detection In Automatic Generation Control: Exploration Of Automated Parameter Generation And Low-Rate Attacks, Yatish R. Dubasi

Computer Science and Computer Engineering Undergraduate Honors Theses

Automatic Generation Control (AGC) is a key control system utilized in electric power systems. AGC uses frequency and tie-line power flow measurements to determine the Area Control Error (ACE). ACE is then used by the AGC to adjust power generation and maintain an acceptable power system frequency. Attackers might inject false frequency and/or tie-line power flow measurements to mislead AGC into falsely adjusting power generation, which can harm power system operations. Various data forgery detection models are studied in this thesis. First, to make the use of predictive detection models easier for users, we propose a method for automated generation …

Achieving Differential Privacy And Fairness In Machine Learning, Depeng Xu

Graduate Theses and Dissertations

Machine learning algorithms are used to make decisions in various applications, such as recruiting, lending and policing. These algorithms rely on large amounts of sensitive individual information to work properly. Hence, there are sociological concerns about machine learning algorithms on matters like privacy and fairness. Currently, many studies only focus on protecting individual privacy or ensuring fairness of algorithms separately without taking consideration of their connection. However, there are new challenges arising in privacy preserving and fairness-aware machine learning. On one hand, there is fairness within the private model, i.e., how to meet both privacy and fairness requirements simultaneously in …

A Comparison Of Medical Article Transport Approaches, Andrew White

Honors Scholar Theses

Our senior design project is to develop a product named the Smartbox - a container capable of safely carrying and monitoring medical articles and accommodate a UAV drone carrying the container. These medical articles include sensitive medicines and human organs for transplantation. Speed, safety, and reliability are a must in this field, as the stakes if a payload is lost or improperly maintained can be life threatening. This project aims to improve on the existing medical transport logistics chains in use today. Time is the most important factor in transportation: many organs simply cannot survive outside of the human body …

Design And Assembly Of High-Temperature Signal Conditioning System On Ltcc With Silicon Carbide Cmos Circuits, Sajib Roy

Graduate Theses and Dissertations

The objective of the work described in this dissertation paper is to develop a prototype electronic module on a low-temperature co-fired ceramic (LTCC) material. The electronic module would perform signal conditioning of sensor signals (thermocouples) operating under extreme conditions for applications like gas turbines to collect data on the health of the turbine blades during operation so that the turbines do not require shutdown for inspection to determine if maintenance is required. The collected data can indicate when such shutdowns, which cost $1M per day, should be scheduled and maintenance actually performed. The circuits for the signal conditioning system within …