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 ...

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

n/a

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

Overview: Space Security: Possible Issues And Potential Solutions, Ziad I. Akir

Online Journal of Space Communication

Space communication has become an integral component of our overall global telecommunication infrastructure. Satellites are being used for telecommunication, business, entertainment, education, Internet, navigation, remote sensing, imaging, and weather forecasting.

Satellites are also providing backup communication capabilities when terrestrial communication is interrupted in cases such as earthquakes or other natural (or unnatural) disasters. The September 11th events in 2001 demonstrated the value of redundant satellite systems in supporting rescue efforts.

Overview: The Increasing Threat To Satellite Communications, Sean Patrick Bain

Online Journal of Space Communication

Communication security has been a priority since the beginning of recorded history. The survival of human cultures has always relied on the use of accurate information transported over distances. The interception of this information, preventing its reception or its misuse, can alter the course of nations. As technology advances, so too does the threat to modern satellite communication. The methods of interfering with or intercepting satellite signals are numerous and need to be better understood.

As has been demonstrated by a small team of undergraduate students, the capability to intercept the nation's communication satellite signals is no longer limited ...

Issue 6: From The Guest Editor, Kathleen Sweet

Online Journal of Space Communication

Guest editor introduction.

Structural Reform For It Competitiveness In Japan, Kei Hata

Online Journal of Space Communication

Five years ago, in order to publicize the necessity for the Japanese government to have an Information Technology policy that until then was largely ignored, as a member of the House of Counselors of the Japanese Diet, I created an urgent proposal and presented it to Prime Minister Hashimoto.

Issue 5: Contributors, Bruce Elbert

Online Journal of Space Communication

List of issue 5 contributors.

Bridging The Digital Divide: Towards A New Paradigm, Virgil Labrador

Online Journal of Space Communication

My direct experience in the "digital divide" was when I was marketing director for a band-new state-of-the-art program origination and satellite transmission facility in Singapore seven years ago in 1996. Our first and anchor client was the highly successful Discovery Network--which housed in our facility the first all-digital channel to the Asia-Pacific market.

Bridge Over Troubled Skies: Satellite Broadband And The Digital Divide, Phillip L. Spector

Online Journal of Space Communication

A few years ago, at the height of the Internet boom, pundits often spoke of "Internet time." They meant many things by this reference, but certainly there was a recognition that a key strength of the Internet is the fast communications speeds involved. While the concept of "Internet time" has faded somewhat with the bloom on the Internet rose, it is still the case that ever-increasing numbers of Americans and others in the world have access to high-speed Internet services. Through this access, they are able to refer quickly to a myriad of resources that have made the Internet an ...

The Digital Divide… Teach A Man To Fish!, Vince Waterson

Online Journal of Space Communication

Recently Kim Hak-Su, Executive Secretary of the United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP) that co-organized the regional conference together with the Japanese Government and other collaborators, acknowledged that more work is needed. "The Tokyo Declaration is directional", he said. "We need more meetings".

Strengthening Access To Communications Policy & Regulatory Guidelines For Satellite Services, David Hartshorn

Online Journal of Space Communication

This work is designed to help bridge the "Regulatory Divide" that continues to thwart end users' efforts to obtain affordable communications. From tele-medicine to distance learning to rural telecenters to disaster recovery to enterprise networks, the satellite industry is offering not only telecommunications solutions for the "have nots", but also the regulatory tools to enable the public sector to fulfill their policy objectives.

Technological Issues: A Day In The Life Of A Satcom Engineer In Nigeria, Andy Hope

Online Journal of Space Communication

The day began early, like all African days.

Technological Issues: The Citizen Initiated Performance Assessment (Cipa) Initiative Through Wireless Technology, William Stowe

Online Journal of Space Communication

Many governments, including my own that serves a population of about 200,000 Central Iowans, have been reluctant to invest in technologies supporting e-government services. The operating assumption for this reluctance is that the "digital divide" delivers the benefits of e-government to the wealthiest and often most educated citizens, effectively diverting resources to constituencies traditionally less reliant on government services than the poor who are often left on the down side of the "digital divide". While "digital divide" considerations are and should continue to be a focal point in deciding allocation of scarce financial resources supporting technological improvements, reallocation of ...

Technological Issues: Closing The Digital Divide Through Resource Allocation Techniques, Avi Barda, Zvi Ner, Shaul Laufer

Online Journal of Space Communication

It is only after access to technology is assured that computer literacy can begin. Access is not simply having access to up-to-date technology; it should also include access to qualified teachers, appropriate software and Web content. Vital to this issue is the quality and quantity of the access.

The optimisation of the bandwidth use, obtained by implementing bandwidth allocation schemes and suited protocol solutions, will allow providing improved quality of service and reduced cost of broadband Internet access. This technology will allow the provision of QoS-based broadband services in hazardous environments and in areas where the technological development is less ...

Social And Cultural Issues: The Impact Of Digital Divide On Development And How Satellite Addresses This Problem, Robin Gambu Wani Latio

Online Journal of Space Communication

The paper examines the problem of inaccessibility to education by the vast majority in East Africa, the factors that contribute to education problems and how the digital divide further helps isolate people in the rural communities of the region.

The author proposes satellite technology as the solution to the digital divide and offers reasons to support this proposition. Technology use in Uganda is discussed as a case study to provide further evidence that satellite communications help close the digital divide gap.