• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 416
  • 132
  • 109
  • 77
  • 74
  • 36
  • 15
  • 14
  • 13
  • 11
  • 11
  • 7
  • 6
  • 6
  • 4
  • Tagged with
  • 1083
  • 133
  • 132
  • 112
  • 111
  • 100
  • 97
  • 91
  • 87
  • 71
  • 71
  • 69
  • 66
  • 63
  • 63
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

LAUNCH VEHICLE EXHAUST PLASMA / PLUME EFFECTS ON GROUND TELEMETRY RECEPTION, STARS FT-04-1

McWhorter, Mark 10 1900 (has links)
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / This paper discusses the effect of vehicle exhaust plasma/plume on the ability to receive telemetered data via an S-band RF link. The data presented herein were captured during the launch of the STARS FT-04-1 on February 23, 2006 from Kodiak Launch Center, Kodiak, Alaska using Alaska Aerospace Development Corporation’s (AADC) Range Safety and Telemetry System (RSTS), designed and integrated by Honeywell.
122

Elastic travel demand analysis - An application to the West link railway in Gothenburg

Ravanbakhsh, Samyar January 2016 (has links)
Today the regional railway system lacks the capacity at the central station in order to meet the demand for both the public and freight transportation. The West link is a railway infrastructure project that is expected to both increase train commuting and also increase the train capacity at the central station in Gothenburg. The purpose of this thesis work is to do an elastic demand analysis between car traffic and the West Link in modal shift to determine how many travelers will change mode. Also traffic simulations will be made to investigate the traffic conditions around the stations when the West link has been implemeted. The simulation results showed that nowadays there are congestions on the major highways and some of the smaller low capacity roads. In the future, congestions will become more significant if no countermeasures are implemented like the West link. In the elastic demand analysis the results were overall around 47% – 51% on a demand of between 350 000 – 400 000 trips. As a conclusion it cannot be said whether the West link will ease the pressure on car traffic or not. The reasons are that the population will increase about 100 000 inhabitants until 2030 and the West link is assumed by the region to have this amount of travelers each day. This would result in the same traffic pressure as today with congestions in certain parts. If the number of West link users will be around 200 000, as the results of this thesis shows, then the West link will ease the pressure on car traffic.
123

LAUNCH VEHICLE EXHAUST PLASMA / PLUME EFFECTS ON GROUND TELEMETRY RECEPTION, STARS IFT-14

McWhorter, Mark 10 1900 (has links)
ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper discusses the effect of vehicle exhaust plasma/plume on the ability to receive telemetered data via an S-band RF link. The data discussed herein was captured during the launch of the STARS IFT-14 on February 13, 2005 from Kodiak Launch Center, Kodiak, Alaska using Alaska Aerospace Development Corporation’s (AADC) Range Safety and Telemetry System (RSTS), designed and integrated by Honeywell.
124

CHANNEL ISSUES FOR DESIGN OF THE iNET RADIO LINK PROTOCOL

Britto, Elizabeth, Mwangi, Patricia 10 1900 (has links)
ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / This paper presents the issues related to the modeling and performance of the Radio Channel used in Telemetry. Because of the physical environment one expects stressed channel conditions due to multipath, shadowing, and high doppler shift caused by high speeds of up to mach 3. Prior work has created useful data and models for analysis of these radio channels. This paper will develop features of a channel simulator that will allow for evaluation of radio protocols for iNET. Substantial work has also been done to develop requirements for the iNET networked radio environment. This paper will map these requirements into technical features required for the radio link and consider how these will relate to the effects of the channels.
125

A LOOK AT CELLULAR PACKET DATA PERFORMANCE FOR APPLICATION IN iNET

Webley, Kayonne 10 1900 (has links)
ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / The integrated Network Enhanced Telemetry (iNET) environment is meant to build and improve on the existing unidirectional legacy telemetry links. The optimized network would have to be capable of providing bi-directional, spectrally efficient, reliable, dynamically allocated, real time or near real time access to video and other types of test data over a shared bandwidth, high capacity network. Developed specifically for providing a reliable means of communications for large numbers of users, cellular technology seems particularly suited to addressing iNET’s needs. This paper investigates the creation of a cellular model for enhanced throughput for data users wherein a user would dynamically be allocated high data rates dependent on parameters such as the received signal to noise ratio (SNR). Our future work will develop the average data performance, comparing both the time division multiple access (TDMA) and code division multiple access (CDMA) environments for potential application in iNET.
126

LINK AVAILABILITY AND BIT ERROR CLUSTERS IN AERONAUTICAL TELEMETRY

Jefferis, Robert P. 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Radio frequency power margins in well planned line-of-sight (LOS) air-to-ground digital data transmission systems usually produce signal to noise ratios (SNR) that can deliver error free service. Sometimes field performance falls short of design and customer expectations. Recent flight tests conducted by the tri-service Advanced Range Telemetry (ARTM) project confirm that the dominant source of bit errors and short term link failures are “clusters” of severe error burst activity produced by flat fading, dispersive fading and poor antenna patterns on airborne vehicles. This paper introduces the techniques used by ARTM to measure bit error performance of aeronautical telemetry links.
127

Telemetry Chart Recording Via Direct Digital Link

Smith, Grant M., Alexander, James H. 10 1900 (has links)
International Telemetering Conference Proceedings / October 17-20, 1988 / Riviera Hotel, Las Vegas, Nevada / Mission safety and cost-efficiency concerns have resulted in a resurgence of interest in real-time strip chart recorders. But conventional recorder technologies require inordinate maintenance and daily calibration. Attempts at strip chart emulation involving costly dedicated microcomputers and CRT's have failed, because the chart itself is not real-time, a basic requirement. The concept of an inexpensive, direct digital link to a telemetry processing computer (VAX, e.g.) is discussed. A thorough examination of real-time monitoring of critical, non-repeatable data is presented. Objectives: An automated, turn-key telemetry data system. Reduce the routine maintenance required by conventional recording systems; eliminate the need for digital-to-analog converters (DAC's); and improve the efficiency of range personnel and the integrity of recorded data.
128

Data Handling System for IRS

Rajyalakshmi, P. S., Rajangam, R. K. 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1987 / Town and Country Hotel, San Diego, California / The three axis stabilized Indian Remote Sensing Satellite will image the earth from a 904 Km polar - sun synchronous orbit. The payload is a set of CCD cameras which collect data in four bands visible and near infra-red region. This payload data from two cameras, each at 10.4 megabits per sec is transmitted in a balanced QPSK in X Band. The payload data before transmission is formatted by adopting Major and Minor frame synchronizing codes. The formatted two streams of data are differentially encoded to take care of 4-phase ambiguity due to QPSK transmission. This paper describes the design and development aspects related to such a Data Handling System. It also highlights the environmental qualification tests that were carried out to meet the requirement of three years operational life of the satellite.
129

Beam-Forming-Aware Link-Adaptation for Differential Beam-Forming in an LTE FDD System / Lobformingsmedveten Länkadaptation för Differentiell Lobformning i ett LTE FDD System

Karlsson, Mikael January 2016 (has links)
The ability for base stations to be able to beam-form their signals, directing the signal energy to specific users, is a topic of research that has been heavily studied during the last decades. The beam-forming technique aims to increase the signal-to-interference-and-noise-ratio of the user and, consequently, increase the capacity and coverage of the communication system. One such method is the Differential Beam-Forming technique, that has been developed at Ericsson Research. In this version of beam-forming, the beams can be dynamically sharpened and widened when tracking a specific terminal, to try to optimize the signal energy sent to that terminal. Beam-forming, however, makes the link-adaptation algorithm process substantially harder to perform. The reason for this is that the link-adaptation algorithm now has to take into account not only the changing radio environment, but also the changing transmit signal that is being beam-formed. Fortunately, since the beam-formed signal is known at the point of transmission, there should be a potential to utilize this knowledge to make the link-adaptation more efficient. This thesis, investigates how the link-adaptation algorithm could be changed to perform better in beam-forming setups, as well as what information from the beam-forming algorithm that could be included and utilized in the link-adaptation algorithm. This is done by designing and investigating three new link-adaptation algorithms, in the context of Differential Beam-Forming in an LTE FDD system. The algorithms that has been designed are both of a beam-forming-aware and beam-forming-unaware character, meaning if the beam-forming information is utilized within the algorithm, or not. These algorithms have been simulated for different base station antenna array-sizes. Unfortunately, due to simulator restrictions, the terminals have been simulated in a stationary environment, which has proven to be a limiting factor for the results. However, the results still show that smarter beam-forming-aware link-adaptation could possibly be used to increase the performance of the link-adaptation when using beam-forming.
130

ON THROUGHPUT ANALYSIS OF THE MARS IN-SITU ARQ PROTOCOL

Liang, Robert, Kwan, Bruce, Florens, Cedric 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Combating harsh and unpredictable channel environments is a part of the design of any in-situ communication system (i.e. rover to lander, rover to orbiter, etc.). Channel characteristics can range from simple additive white Gaussian noise (AWGN) channels to more bursty fading channels found in rover to orbiter links (i.e. canyon scenarios and typical orbiter passes around mountain ranges). A combination of forward error correction and automatic repeat request (ARQ) schemes are commonly used to provide a more robust communications link. ARQ enhances the communication link particularly for bursty fading channels. Go-Back-N is a commonly used ARQ scheme and is an option in the newly developed Consultative Committee for Space Data Systems (CCSDS) Proximity-1 Link protocol [7], a data link layer protocol targeted specifically for in-situ applications. Optimization of frame sizes and retransmission persistence of the ARQ scheme require a good analytical model of how the scheme performs over various channel conditions. In this paper, an analytical framework for modeling the COP-1 protocol is presented for both AWGN channels along with bursty fading channels. A Gilbert-Elliot two-state Markov model is used to model a bursty fading channel.

Page generated in 0.2407 seconds