Space Communications - Volume 18, issue 1-2

Article Type: Other

Citation: Space Communications, vol. 18, no. 1-2, pp. 1-1, 2002

Article Type: Other

Citation: Space Communications, vol. 18, no. 1-2, pp. 3-3, 2002

Article Type: Other

Citation: Space Communications, vol. 18, no. 1-2, pp. 5-5, 2002

Authors: Bauer, Robert | Krawczyk, Richard | Irwin, Dennis | Kruse, Hans

Article Type: Research Article

Abstract: The Advanced Communications Technology Satellite (ACTS) program was slated for decommissioning in October 2000 as was announced at the 6th Ka‐band Utilization Conference in May 2000. Quite a celebration was had at that event too, centering on the decommissioning of this very successful technology program [1]. With plans in place to move the spacecraft to an orbital graveyard and then shut the system down, NASA was challenged to consider the feasibility of extending operations for education and research purposes, provided that an academic organization would be willing to cover operations costs. Continuing operations of the system was determined viable and …in the fall of 2000, an announcement was made by NASA to consider extending operations. Plans are now in place to continue the operations of ACTS through a university‐based consortium led by Ohio University, Athens, Ohio. Initial plans are for two more years of operations, with options to extend up to a total of four years. This paper will present the change in plans to continue operations of ACTS. A description of the multi‐month transition of the spacecraft to its new and final orbital location is provided. With the spacecraft at this new location, an update on its performance is presented as well as estimates of long‐term performance. The consortium development will be presented along with its organization, membership and operations plans for using ACTS. Show more

Citation: Space Communications, vol. 18, no. 1-2, pp. 7-12, 2002

Authors: Brooker, Ralph L.

Article Type: Research Article

Abstract: Ka‐band offers the promise of very low‐cost broadband terminals deployed in quantities an order of magnitude greater than the total number of all the two‐way C‐ and Ku‐band terminals installed since the birth of satellite communications. For small terminals, installation and commissioning costs can easily overwhelm equipment cost unless the terminal is pre‐qualified for interference‐limiting performance without on‐site testing. The satellite industry has addressed this issue for C‐ and Ku‐band with mutually‐recognized type approval procedures, but operation at 20 and 30 GHz gives rise to special considerations in equipment design, qualification, and testing. Work is beginning to adapt existing type …approval procedures for Ka‐band and to review performance standards for discrepancies, with the ultimate goal of universal type approval procedures and standards recognized not only by satellite operators but also by government administrations. Show more

Citation: Space Communications, vol. 18, no. 1-2, pp. 13-16, 2002

Authors: Chitre, Prakash | Inukai, Thomas

Article Type: Research Article

Abstract: For Ka‐band satellite systems to compete successfully in the broadband marketplace, two fundamental challenges must be addressed: cost, and the quality and performance of the offered services/applications. Specific issues related to these challenges are discussed and a set of solutions is proposed. The solutions range from the development of common standards to specific techniques to mitigate the effect of rain fades in Ka‐band frequencies and the propagation delay of the geosynchronous satellite. Finally, dynamic resource allocation and congestion control techniques are described which exploit the key characteristics of Ka‐band satellite systems and maximize the availability of satellite capacity to user …applications. Show more

Citation: Space Communications, vol. 18, no. 1-2, pp. 17-21, 2002

Authors: Hsu, Eddie | Hung, Chaw | desJardins, Richard | Foster, Mark | Gilstrap, Ray | Chao, Larry | Gill, Mike | Tatsumi, Haruyuki | Edelson, Burt | Helm, Neil | Rae, Al Mac | Kadowaki, Naoto | Yoshimura, Naoko | Takahashi, Takashi | Gary, Pat | Lang, Paul | Kranacs, Kevin | Shopbell, Patrick | Walker, Gretchen | Wellnitz, Dennis | Gargione, Frank

Article Type: Research Article

Abstract: In 1993, a proposal at the Japan‐US Science, Technology, and Space Applications Program (JUSTSAP) workshop led to a subsequent series of satellite communications experiments and demonstrations, under the title of Trans‐Pacific High Data Rate Satellite Communications Experiments. The first phase of which was a joint collaboration between government and industry teams in the United States and Japan that successfully demonstrated distributed high definition video (HDV) post‐production on a global scale using a combination of high data rate satellites and terrestrial fiber optic asynchronous transfer mode (ATM) networks. This was followed by the Phase‐2 Internet Protocol (IP) based experiments and demonstrations …[4–6] in tele‐medicine and distance education, using another combination of two high data rate satellites and terrestrial fiber optic networks. The Visible Human tele‐medicine and Remote Astronomy distance education demonstrations and their use of distributed systems technologies afforded an opportunity for people around the world to work together as a virtual team under one roof, using resources thousands of miles away as if they were next to each other. The visible human activity demonstrated global‐scale interactive biomedical image segmentation, labeling, classification, and indexing using large images; the remote astronomy activity demonstrated collaborative observation and distance education at multiple locations around the globe and the transparent operations of distributed systems technologies over a combination of broadband satellites and terrestrial networks. The use of Internet Protocol related technologies allowed the general public to be an integral part of the exciting activities, helped to examine issues in constructing a global information infrastructure with broadband satellites, and afforded an opportunity to tap the research results from the (reliable) multicast and distributed systems communities. This paper summarizes the Phase‐2 of Trans‐Pacific series of experiments and demonstrations by an international team in Canada, Japan, and the United States. Show more

Citation: Space Communications, vol. 18, no. 1-2, pp. 23-30, 2002

Authors: Bever, Mark | Willoughby, Scott | Wiswell, Eric | Ho, Kenton | Linsky, Stuart

Article Type: Research Article

Abstract: In response to the demands for broadband satellite systems and services, TRW initiated the Gen*Star processing payload in 1995. The Gen*Star system objectives of profitable broadband connectivity with seamless interfaces to a terrestrial infrastructure imply highly reliable network nodes in space. To achieve these objectives, robust communications links and sophisticated onboard signal and data processing are required. The Gen*Star satellite payload provides those communication links and processing functions in a package suitable for launch into space, using technologies designed to operate for years in space. The TRW Gen*Star payload development incorporated business analysis, network simulation and analysis, payload technologies, …network operations, and terminal concepts. Since initiating the effort, TRW has completed simulations, a functional hardware prototype of the payload, and a complete engineering model payload. The end‐to‐end engineering model of a broadband payload operating at Ka‐band features engineering model hardware built to flight production standards and tested to flight environmental conditions. This presentation and paper will summarize features and capabilities of the TRW broadband engineering model payload and the payload test results. Show more

Citation: Space Communications, vol. 18, no. 1-2, pp. 31-38, 2002

Authors: Acosta, R. | Johnson, S. | Sands, O. | Lambert, K.

Article Type: Research Article

Abstract: Phased Array Antennas (PAAs) using patch‐radiating elements are projected to transmit data at rates several orders of magnitude higher than currently offered with reflector‐based systems. However, there are a number of potential sources of degradation in the Bit Error Rate (BER) performance of the communications link that are unique to PAA‐based links. Short spacing of radiating elements can induce mutual coupling between radiating elements, long spacing can induce grating lobes, modulo 2π phase errors can add to Inter Symbol Interference (ISI), phase shifters and power divider network introduce losses into the system. This paper describes efforts underway to test and …evaluate the effects of the performance degrading features of phased‐array antennas when used in a high data rate modulation link. The tests and evaluations described here uncover the interaction between the electrical characteristics of a PAA and the BER performance of a communication link. Show more

Citation: Space Communications, vol. 18, no. 1-2, pp. 39-45, 2002

Authors: Correnti, Andrew

Article Type: Research Article

Citation: Space Communications, vol. 18, no. 1-2, pp. 47-52, 2002