Aerospace Engineering Commons^™

Array-Based Guided Wave Source Location Using Dispersion Compensation, Andrew Downs, Ronald A. Roberts, Jiming Song

Electrical and Computer Engineering Publications

An important advantage of guided waves is their ability to propagate large distances and yield more information about flaws than bulk waves. Unfortunately, the multi-modal, dispersive nature of guided waves makes them difficult to use for locating flaws. In this work, we present a method and experimental data for removing the deleterious effects of multi-mode dispersion allowing for source localization at frequencies comparable to those of bulk waves. Time domain signals are obtained using a novel 64-element phased array and processed to extract wave number and frequency spectra. By an application of Auld’s electro-mechanical reciprocity relation, mode contributions are ...

Navigation Performance Of Line/Plane Intersection Lidar Model In Conjunction With Opportunistic Feature Tracker, Michael R. Hansen

All Graduate Theses and Dissertations

With NASA awarding numerous contracts to build commercial lunar payload spacecraft and human lunar landers, the need for high precision navigation has increased. Traditional inertial navigation alone is not sufficient to autonomously land a vehicle on hazardous lunar terrain. Terrain relative navigation (TRN) systems have been explored in previous research that exploit camera observations of known landmarks. Such approaches require the flight electronics to correctly match features of the observed landmarks to an onboard database, in the drastically varying lighting conditions of moon. This paper explores the performance of a TRN system that does not rely on apriori landmark identification ...

Issue 7: Contributors, David Hartshorn, Martin Jarrold

Online Journal of Space Communication

List of Issue 7 Contributors.

Future Solutions: Universal Access, David Hartshorn

Online Journal of Space Communication

Today, the nations of the world have an immediate opportunity to advance essential telecommunication policy objectives through harmonisation of regulations governing the use of fixed satellite-based network solutions.

Future Solutions: Access To Ict: A Tale Of Three Briefings, David Hartshorn

Online Journal of Space Communication

If your inbox is anything like mine, then you already know that the publication of satellite communications reports has become an industry unto itself. But that's not to say that it's always an end unto itself. On the contrary.

Regulatory Reform: Strengthening Access To Information & Communications Technologies: Guidelines To Facilitate Policy & Regulation For Satellite Services, Global Vsat Forum

Online Journal of Space Communication

This document was prepared by GVF, an association of organisations engaged in the delivery of advanced broadband and narrowband satellite services to consumers, and commercial and government enterprises worldwide.

Regulatory Reform: In The Land Of The 'Coffeenet', Martin Jarrold

Online Journal of Space Communication

Sitting down to write this article at a desk some 30 miles south of central London, and less than one degree west of the Greenwich meridian, I became immediately more conscious than usual of geography. The frequently interwoven use of such western-centric cartographic labels as Middle East, and Far East, with the geographically more precise terms of Western or Central Asia, and East and South-East Asia, sometimes causes us to confuse the actual proximity of Europe's, much larger, near-neighbour.

Regulatory Reform: Asia's Great Step Forward, David Hartshorn

Online Journal of Space Communication

This paper was presented at Connect-World Asia Pacific, June 2002.

Forget about a great leap forward. All that's needed to facilitate communications in Asia are a few small steps. Indeed, today all nations of the world have an immediate opportunity to advance essential telecommunication policy objectives through harmonisation of regulations governing the use of telecommunications solutions.

Regulatory Reform: Wanted: A Bridge For Africa's Digital Divide Apply: Pretty Much Anywhere In Africa Quote Reference: Vsat, Martin Jarrold

Online Journal of Space Communication

For Africa, and for the economy of the whole planet, those hundreds of millions of people across the continent who are currently denied reasonable access to even simple voice service represent a vast untapped pool of creativity. This very large and potentially very powerful economic dynamo demands access to more than the simplest tools of communication, and requires the means to unleash the potential productivity of its own knowledge-base into an increasingly connected world. The International Telecommunications Union acknowledges this, as does its sister organisation, the United Nations. The Global VSAT Forum enjoins you to acknowledge it too.

Overview: A+B+C = Vsat, Martin Jarrold

Online Journal of Space Communication

The benefits of VSAT systems and services are being realised in all spheres across the globe, both private and public. Banks, government departments, schools, hospitals, home offices, small enterprises, multi-national corporates, and rural telephony… all sectors are seizing upon the opportunity to get connected through satellite communications.

Overview: Satellite Communication In Ghana - Challenges And Prospects, Kwasi Boateng

Online Journal of Space Communication

Busy Internet is a Ghanaian ISP that uses satellite connectivity to bring Internet to West Africans. The operations of this ISP illustrate the reliability, versatility and efficiency of, VSAT, (Very Small Aperture Terminal) networks in delivering fast broadband Internet services.

Overview: The View From 22,300 Miles High, David Hartshorn

Online Journal of Space Communication

Asia's geography, claiming many of the world's highest peaks, has provided a dramatic setting for a climbing expedition that began decades ago, when the satellite communications community took its first step on the lower slopes of the mountain.

Overview: Politics And Technology Converge: Case Studies On The Effects Of Regulatory Reform On Vsat Adoption In Developing Countries, Emmanuel Adugu, Kwasi Boateng, D. Flournoy, Eric Gavua, Wencelous Kaswoswe, Miao Zhang

Online Journal of Space Communication

Developing countries are actively implementing satellite data networks, and have undertaken policy reforms to facilitate such networks. This research examines how regulatory changes have resulted in the removal of barriers relating to the deployment of access technologies and growth in connectivity, especially in VSAT installations for low cost Internet access. In addition, this research seeks to identify the socio-economic impact of emerging data network applications in government, business, health and education. In some cases, government offices have been the driver of change; in other cases, businesses have been the ones to initiate and press these developments forward.

Overview: Pipelines Of The Skies, Errol Olivier

Online Journal of Space Communication

Advances in fixed satellite technology are enabling oil and gas concerns to enhance the efficiency of offshore operations with cost-effective voice and data network solutions.

Issue 7: From The Guest Editors, David Hartshorn, Martin Jarrold

Online Journal of Space Communication

During the past 15 years, the international satellite communications industry has been developing and refining network solutions such that today, there are more than one million so-called Very Small Aperture Terminal (VSAT) systems installed and operating in more than 120 countries.

Space And Defense – Volume Twelve – Number One – Winter 2021, Space And Defense Journal

Space and Defense

No abstract provided.

Satellite Security And Performance In An Era Of Dual Use, Joseph N. Pelton

Online Journal of Space Communication

Since the mid-1990s the U.S. Government and military forces have placed more and more reliance on commercial satellite systems for military communications of a non-tactical nature. Requirements such as the U.S. Armed Forces Radio and Television require a great deal of bandwidth but do not require any special security protection. Further there are many other forms of communications involving national security or defense systems where a varying degree of security is required. Many of these applications do not require a very high level of "top secret" protection since these communications do involve tactical, strategic or highly classified messages ...

International Guidelines For The Preservation Of Space As A Unique Resource, Phillip D. Anz-Meador

Online Journal of Space Communication

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Overview: Satellite Signal Security: Copyright Protection Korean Dbs Content And Transaction Security, Don Flournoy

Online Journal of Space Communication

As a result of new developments in broadband communication, residential users, office workers and those who move from place to place have more ways to access the programming and services they want when they want them.

Space-Based Offensive Weapons: Have Policymakers Discussed This Enough?, Kathleen M. Sweet

Online Journal of Space Communication

Arguably, one of the most significant global security policy debates of the 21st century is whether the United States and more specifically the Bush Administration should develop and deploy space-based weaponry. The age of space is upon us. But how convinced is the rest of America, the West and potential adversaries of the legitimate need to do so? For almost half a century, the world's space powers have abstained from deploying such weapons as basic unwritten policy. To date, the military has been limited to surveillance, navigation and communications satellites