SWITCHING TO THE FUTURE OF RANGE COMMUNICATIONS AT EDWARDS AFB
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Proceedings 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.Abstract
The Edwards Digital Switch (EDS) provides mission critical voice and time-spaceposition information (TSPI) communication switching capability to the Edwards Test Range. The present system has been in operation for about 10 years. The core of this system is based on widely used commercial-off-the-shelf (COTS) time-slot interchange switches that were designed for a 40-year service life. The application layers of the system, comprising the command/control elements and the communications and user interfaces, were custom developed by the prime contractor to satisfy the performance requirements of the Air Force Flight Test Center (AFFTC). Problems with the current system include difficulty in obtaining replacement items for equipment developed by the prime contractor and higher than expected failure rates for this equipment. Based on experience, the service life for the equipment developed by the prime contractor appears to be about 15 years. Another problem is that lower cost packet switches are taking market share from the more traditional time-slot interchange switches. This factor tends to accelerate the obsolescence of the existing COTS equipment. Solutions are being investigated to update or replace the EDS. One solution is to reuse the existing COTS core equipment and replace the present application layers, preferably with COTS. Another solution is to replace the entire system with COTS or vendormodified COTS hardware and software.Sponsors
International Foundation for TelemeteringISSN
0884-51230074-9079
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ASSESSMENT OF PHOTONIC SWITCHES AS FUTURE REPLACEMENT FOR ELECTRONIC CROSS-CONNECT SWITCHESThis paper presents the future of optical networking via photonic switches as a potential replacement for the existing electronic cross-connects. Although optical amplifiers are now mainstream and wave division multiplexing (WDM) systems are a commercial reality, the industry’s long-term vision is one of the all-optical network. This will require optical switching equipment such as all-optical or “photonic” cross-connect switches that will provide packet switching at an optical layer. Currently, as voice calls or data traffic are routed throughout Range and commercial networks, the information can travel through many fiber-optic segments which are linked together using electronic cross-connects. However, this electronic portion of the network is the bottleneck that is preventing the ideal network from achieving optimal speeds. Information is converted from light into an electronic signal, routed to the next circuit pathway, then converted back into light as it travels to the next network destination. In an all-optical network, the electronics are removed from the equation, eliminating the need to convert the signals and thereby significantly improving network performance and throughput. Removing the electronics improves network reliability and restoration speeds in the event of an outage, provides greater flexibility in network provisioning, and provides a smooth transition when migrating to future optical transmission technologies. Despite the fact that photonic switching remains uncommercialized, it now seems apparent that the core switches in both the public networks and DoD Range networks of the early 21st century will probably carry ATM cells over a photonic switching fabric.
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Network Monitor/Control Concept for the Western Union Satellite Switched TDMA Advanced Westar SystemA description of the network monitor and control and TT&C concepts for the Western Union Satellite Switched TDMA Advanced Westar System is presented. The paper includes a brief description of the major system elements, their functional relationship to the network management center, and the methods to be used for monitoring/responding to station/network performance, reallocating: burst assignments, satellite switch assignments and point-to-point (multipoint) connectivity; and failure restoration of satellite communication payload service. Network monitoring and control is achieved via information exchanges between the system Network Management Center and the various system elements including: Network Earth Stations, Master Reference Stations, the White Sands TT&C Center, Western Union O&M Centers, and Western Union Administrative Center. Communication between the TMC and these facilities will be established via both satellite (8 KBPS orderwire channel) and terrestrial links. Fine/Course timing between the network earth stations and the satellite switch will be provided via reference bursts transmitted by the system Master Reference Stations into each of the four zones associated with the individual satellite channels.
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Formation of Dicentric and Acentric Chromosomes, by a Template Switch Mechanism, in Budding YeastChromosomal rearrangements occur in all organisms and are important both in the evolution of species and in pathology. In this dissertation I show that in Saccharomyces cerevisiae, or budding yeast, one type of chromosomal rearrangement occurs when inverted repeats fuse, likely during DNA replication by a novel mechanism termed "faulty template switching". This fusion can lead to the formation of either a dicentric or acentric chromosome, depending on the direction of the replication fork. Dicentric chromosomes are inherently unstable due to their abnormal number of centromeres, and thus undergo additional chromosomal rearrangements and chromosome loss.
