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  • 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.
81

Performance of mobile GIS in conjunction withinternet bandwidth in rural areas

Reynisson, Jón Ágúst January 2015 (has links)
The emerging techniques of mobile GIS applications, its abilities and its implied limitations ofinternet connections is the main subject in this study. Many of the operations that mobile devicesuse are dependent on mobile internet connectivity. Therefore the potential for it in well connectedareas is great but how would they function in less connected areas? Mobile GIS, which is todaymostly used in devices as smart phones and tablets, has internet connectivity for uploading anddownloading files and other data. Mobile GIS is also dependent on location-based services thatenable the device to get information or take action from the current location of the device. Thisresearch examines the potential usage of mobile GIS in conjunction with the bandwidth of wirelesstechnologies. It is important to study this issue to see if mobile applications can perform upload anddownload tasks within reasonable time in poor mobile coverage. To test the possibilities of mobileGIS in rural areas a test environment is set up in a mobile GIS application for septic tanks. Thetesting is performed by uploading and downloading data with real GIS actions from pre-selectedlocations that have low mobile coverage. The study is comparing the measurements with a scale ofacceptable time for download and upload. The result for registering (uploading) a new point inmobile GIS with three small images is that it requires at least 330 Kbit/s connection to transfer thedata within acceptable time. The results for uploading data without images and downloading giveseven better results and are not as dependent on a good connection for transferring within acceptabletime. The conclusion is that mobile gis applications are able to run within acceptable time measuresin rural areas. The results and other sources were used to make general guidelines for mobile GISapplications for use in rural areas.
82

Multiple-Input Multiple-Output Systems for Spinning Vehicles

Petersen, Samuel 10 1900 (has links)
ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / This paper investigates the performance of a multiple-input multiple-output (MIMO) digital communication system, when the transmitter is located on a spinning vehicle. In particular, a 2x2 MIMO system is used, with Alamouti coding at the transmitter. Both Rayleigh and Rayleigh plus line-of-sight, or Rician, models combined with a deterministic model to simulate the channel. The spinning of the transmitting vehicle, relative to the stationary receive antennas, modulates the signal, and complicates the decoding and channel parameter estimation processes. The simulated system bit error rate is the primary performance metric used. The Alamouti channel code is shown to perform better than the maximal ratio receiver combining (MRRC) and single receiver (2x1) system in some circumstances and performs similarly to the MRRC in the broadside case.
83

L-Band Coplanar Slot Loop Antenna for iNET Applications

Nithianandam, Jeyasingh 10 1900 (has links)
ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / In this article we present a design of an L-band slot loop antenna with a dielectric loaded conductor backed coplanar waveguide (CBCPW) feed. The coplanar slot loop antenna has a transmission line resonator in series. We used full wave electromagnetic simulations with Ansoft's high frequency structure simulator (HFSS) software in the design of the coplanar slot loop antenna. The series transmission line resonator helps to tune the coplanar slot loop antenna and reduce its size. We present here results on return loss and radiations patterns of coplanar slot loop antenna obtained from HFSS simulations.
84

MATCHED FILTER-BOUND OF BANDWIDTH EFFICIENT MULTISCALE WAVELET SIGNALING OVER MULTIPATH RAYLEIGH FADING CHANNELS

Lo, Chet, Moon, Todd K. 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In this paper, we extended the matched filter bound (MFB) of time-discrete multipath Rayleigh fading channels derived in [1,2] for multiscale wavelet signaling communication.
85

DOPPLER BANDWIDTH CHARACTERIZATION OF ARTM CHANNEL SOUNDING DATA

Landon, David 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Data from ARTM channel sounding test flights is examined to characterize the dynamic channel behavior of aeronautical telemetry channels. The dynamic behavior is characterized using the Doppler power spectrum. The width of the Doppler power spectrum is the Doppler bandwidth of the channel which indicates the required bandwidth of adaptive detection techniques such as adaptive equalization, adaptive modulation, adaptive channel selection and adaptive error control coding. Data collected from ARTM Flight 11 suggest a Doppler bandwidth exceeding 6.7 Hz for the channel, but greater accuracy and resolution will only be possible with more data.
86

A VALUABLE TOOL TO HAVE WHEN WORKING WITH PSK DEMODULATORS IS A KNOWLEDGE OF ITS FUNCTIONALITY

Cylc, Linda 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / PSK demodulators have been an integral part of the signal recovery process for decades. Unless a person has designed a demodulator, how much can a person know or understand about its operation? Instruction on how to set up a demodulator’s parameters to acquire a signal is found in a manual. An explanation of why parameters are set a certain way to handle particular input signal characteristics is often not provided in a manual. This paper is designed to be a tool to aid engineers, technicians, and operators who utilize demodulators. Its purpose is to relay the functionality of a demodulator to a user so that he or she can take advantage of its control parameters and status feedback. Knowing the reasons why a demodulator is set to certain parameters may greatly reduce confusion when a system is not working properly. On site troubleshooting may be accomplished without the need to call the manufacturer of the product. Another advantage of understanding the operation will be recognized when interfacing with the manufacturer. A person will be able to relay the information to a design engineer more easily, and will understand more of the engineer’s feedback on the potential problem. Utilizing this paper as an aid to enhance operation of a PSK demodulator will bring a user one step closer to understanding the complexity of its design.
87

THE ART OF INTERNATIONAL SPACE STATION TELEMETRY BANDWIDTH MANAGEMENT

Cerna, Peter J., Klein, Pamela R., Mullett, Joy 10 1900 (has links)
International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The technicalities of sharing telemetry bandwidth have been addressed in design and specification for the builders of the International Space Station. But success in sharing bandwidth comes from building relationships, documenting guidelines, negotiating, understanding human nature, peer review and willingness to participate in an evolving process. The station, 240 miles above Earth, moves through space at 17,000 mph, has its mass added to by humans and machines, regularly docks with visiting spacecraft, has year-round residents, and communicates with space agencies around the globe. Each new module -- with associated computers, multiplexers, and communications buses -- creates additional telemetry demands.
88

FQPSK DEVELOPMENTS RECOMMENDED FOR CCSDS STANDARDIZATION BY NASA JPL

Martin, Warren L. 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / In 1992, international space agencies became concerned that increasing frequency band congestion, together with attempts by the mobile telephone industry to obtain additional bandwidth, would result in substantially more interference incidents. The CCSDS undertook a technical study to identify and recommend more bandwidth efficient modulation schemes, which would permit more users to co-exist in a frequency band while reducing interference incidents. This paper describes the contribution of the Jet Propulsion Laboratory (JPL) to that effort.
89

Making All The Data Available Some Of The Time In Very Large Telemetry Volume Space Applications

Cook, David B. 10 1900 (has links)
International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / What do you do when your downlink telemetry needs outstrip your downlink bandwidth capability? The telemetry needed to support construction and operation of the largest, most complex engineering project ever undertaken, the International Space Station (ISS), already requires utilization of the full capacity of the downlink S-band capacity, yet there are additional systems and capabilities still to be added by NASA and the International Partners. The ISS Command and Telemetry Team has developed a method of swapping packets of telemetry that are intended for special operations, while simultaneously sending essential systems telemetry and less critical telemetry that is needed on a continuous basis. To support this attempt to “make available all of the data at least some of the time” the team developed concepts for grouping telemetry into families that would always be selected as a group and then created a set of metadata associated with these groups. This metadata is pre-defined to support automated selection and scrubbing of telemetry to correspond to major upgrades in the command and control software for the ISS. The new process will at least double the effective S-band downlink bandwidth. It will also provide automated selection, scrubbing, reporting and verification of telemetry selections.
90

PERFORMANCE STUDY OF ENHANCED FQPSK AND CONSTRAINED ENVELOPE MODULATION TECHNIQUES

Borah, Deva K., Horan, Stephen 10 1900 (has links)
International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / This paper investigates the spectral properties and the bit error rate (BER) performance of enhanced FQPSK (EFQPSK) and constrained envelope modulation (CEM) techniques. Both the techniques are found to provide good spectral efficiencies. The EFQPSK signals are found to generate spectral lines for unbalanced data. An analytical spectral study for the spectral lines is presented. While the performance of CEM techniques has been presented in [6] for an ideal nonlinear amplifier, we present results for more realistic amplifiers with AM/AM and AM/PM effects. It is shown that such an amplifier generates spectral regrowth and a predistorter is required to reduce the adverse effects. A BER performance study with/without channel coding is also presented for the two techniques.

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