International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / Shrinking budgets and labor pools have impacted our ability to perform experiments at the Nevada Test Site (NTS) as we did previously. Specifically, we could no longer run heavy cables to remote data acquisition sites, so we replaced the cables with RF links that were transparent to the existing system, as well as being low-cost and easy to deploy. This paper details how we implemented the system using mostly commercial off-the-shelf components.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A spacecraft complying with the CCSDS Packet Telemetry standard generates telemetry data as a stream of packets. Generally, each packet has different requirements for data transfer characteristics (such as delay and reliability). These requirements are called Quality of Service (QoS) requirements. This paper proposes an extension to the CCSDS Packet Telemetry standard to specify QoS requirements of each packet. The method proposed in this paper is to associate with each packet (1) a level of delay tolerance and (2) a level of loss tolerance. This paper shows how packets should be handled based on this QoS information, and demonstrates that most of the QoS requirements for telemetry data transfer can be met by using this information. This paper also addresses some topics for future investigations.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / A multiplexer / demultiplexer design suitable to a wide range of input data types and link formats is presented. Based on the Consultative Committee on Space Data Systems (CCSDS) recommendations for Packet Telemetry, the design translates the prescribed layered architecture into a modular, layered hardware implementation. The design approach minimizes hardware yielding increased reliability and decreased product cost while retaining a high degree of flexibility. This implementation can be applied to flight data acquisition (direct transmission to the ground or recorded), ground data collection (including multi-stream record systems) and inter-range communications. The use of an internationally recognized standard promotes inter-service interoperability and facilitates data handling/routing throughout a wide community.

International Telemetering Conference Proceedings / October 17-20, 1988 / Riviera Hotel, Las Vegas, Nevada / The Goddard Space Flight Center Mission Operations and Data Systems Directorate has developed a Packet Processor card utilizing semi-custom very large scale integration (VLSI) devices, microprocessors, and programmable gate arrays to support the implementation of multi-channel telemetry data capture systems. This card will receive synchronized error corrected telemetry transfer frames and output annotated application packets derived from this data. An adaptable format capability is provided by the programmability of three microprocessors while the throughput capability of the Packet Processor is achieved by a data pipeline consisting of two separate RAM systems controlled by specially designed semi-custom VLSI logic.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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No description available.

The aim of this thesis is to investigate and understand the issues involved in using multicast communications over a non-reliable satellite link and to suggest suitable methods to improve multicast services when used on packet networks. Point-to-multipoint communications have been used for distribution of data. These are mainly found on circuit switched networks where there is bandwidth allocation, ensuring a good transmission link. However, as packet switched networks become more evolved due to their interesting properties of being able to share the available bandwidth, multicast communication is increasingly employed. A satellite link in a packet network is often used to provide connection to remotely located hosts. To use point-to-multipoint communications, especially for real-time applications, across a satellite link, a scheme employing Forward Error Correction (FEC) is presented. The scheme uses an XOR (Exclusive-OR) coding technique to generate the redundancy. It adjusts the rate of coding according to the varying condition of the link. By using this transmission strategy, the proposed scheme is implemented at the transport and the data link layer to enhance multicast communication services. In recent years, there has been a tremendous growth in the number of local and wide area networks. To manage these networks, it is necessary to monitor and analyse the network traffic regularly. Many commercially available analysers are either too expensive or too complicated. Perhaps the greatest setback lies in their presentation of vital information to the users in the form of screen after screen of textual data. Thus, it may require someone of experience to be able to fully understand the situation on the network and this, only after a detailed study of the data. The thesis investigates and proposes a new method of processing and presenting the information that will enhance the flexibility and productivity in the process of network troubleshooting.

The purpose of this paper is to provide an instructional format in the presentation of the clinical application of electroacoustic impedance measurements. Journal articles and impedance procedural booklets were used as a source of data for the information contained in the learning packet. Fundamentals of acoustic theory were treated to show the conceptual relationship of acoustic impedance and acoustic admittance. The terminology, normative data, and clinical interpretation of static acoustic impedance measures were examined. Diagnostically significant variables of the tympanogram were related to the audiometric-medical status of the patient. Clinical application of the acoustic reflex was investigated through descriptions of various pathologies and the particular indications expected in acoustic reflex testing for those pathologies . The learning packet is divided into four sections: impedance versus admittance, static acoustic impedance measurements, tympanometry, and acoustic reflex.

No description available.