• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 10
  • 8
  • 1
  • 1
  • 1
  • Tagged with
  • 26
  • 26
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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.
1

Channel Sounding

Iftikhar, Wajid, Raichl, Jaroslav January 2008 (has links)
<p>This thesis will setup and configure a channel sounding system, further it will set up a software environment for channel model extraction (characteristic of the channel) and evaluation.</p><p>The motivation of the project is to set up and configure a channel sounding system based a Spectral Analyzer (Agilent E4407B), Signal Generator (Agilent E8267D), Signal Studio and Matlab software. The main motivation is to evaluate capability of such a channel sounding system, and see if it can be used for future channel model extraction.</p><p>Channel Sounding is based on emitting RF signal from one antenna and receiving the RF signal at another antenna (spatial place), extracting the channel response. This project will start with getting familiar with the basic operation of the Spectral Analyzer (Agilent E4407B), the Signal Generator (Agilent E8267D) and Signal Studio. Then set up a channel sounding system with previous mentioned equipment. Then as practical exercise some channel sounding and channel model extraction will be conducted. Especially see what kind of parameters those are possible to extract, time delay, propagation paths etc.</p>
2

Channel Sounding

Iftikhar, Wajid, Raichl, Jaroslav January 2008 (has links)
This thesis will setup and configure a channel sounding system, further it will set up a software environment for channel model extraction (characteristic of the channel) and evaluation. The motivation of the project is to set up and configure a channel sounding system based a Spectral Analyzer (Agilent E4407B), Signal Generator (Agilent E8267D), Signal Studio and Matlab software. The main motivation is to evaluate capability of such a channel sounding system, and see if it can be used for future channel model extraction. Channel Sounding is based on emitting RF signal from one antenna and receiving the RF signal at another antenna (spatial place), extracting the channel response. This project will start with getting familiar with the basic operation of the Spectral Analyzer (Agilent E4407B), the Signal Generator (Agilent E8267D) and Signal Studio. Then set up a channel sounding system with previous mentioned equipment. Then as practical exercise some channel sounding and channel model extraction will be conducted. Especially see what kind of parameters those are possible to extract, time delay, propagation paths etc.
3

DESIGN AND EXPERIMENTATION WITH A SOFTWARE-DEFINED ACOUSTIC TELEMETRY MODEM

Doonan, Daniel, Fu, Tricia, Utley, Chris, Iltis, Ronald, Kastner, Ryan, Lee, Hua 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 describes the design and successful development of an acoustic modem for potential use in underwater ecological sensor networks. The presentation includes theoretical study, design and development of both software and hardware, laboratory experiments, full-scale field tests, and the documentation and analysis of field-test results.
4

SHF MULTIPATH CHANNEL MODELING RESULTS

Rice, Michael, Lei, Qiang 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 results of land-based SHF channel modeling experiments. Channel modeling data were collected at Edwards AFB, California at S-Band, X-Band and Ku-band. Frequency domain analysis techniques were used to evaluate candidate channel models. A graphical user interface (GUI) was developed to search for the optimum channel parameters. The model parameters corresponding to different frequencies were compared for multipath events captured at approximately the same locations. A general trend was observed where the magnitude of the first multipath reflection decreased as frequency increased and the delay remained relatively unchanged.
5

ARTM CHANNEL SOUNDING RESULTS – AN INVESTIGATION OF FREQUENCY SELECTIVE FADING ON AERONAUTICAL TELEMETRY CHANNELS

Rice, Michael, de Gaston, David, Davis, Adam, German, Gus, Bettwieser, Christian 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Initial results of wideband channel sounding experiments sponsored by the Advanced Range Telemetry (ARTM) program are presented. Data collected at Edwards EAFB during the Winter 1998-1999, are analyzed in the frequency domain to estimate the number, strength, and delays of the significant multipath reflections observed during the experiments. We observe that the channel is adequately modeled using two or three multipath reflections. The multipath fade events are correlated with recorded bit error rates and transmitter location to provide a comprehensive overview of the channel characteristics. Summaries from two test flights are included where it is seen that the 2- and 3-ray channel models provide excellent models for the data. In general, the 3-ray model captures the essential features of the multipath interference. In this model the first multipath is a strong specular reflection with relative amplitude greater than 0.5 and relative delay in the 30 to 70 ns range. The second multipath is a much weaker reflection with relative amplitude less than 0.5 and relative delay in the 175 to 325 ns range.
6

THE EFFECTS OF CARRIER FREQUENCY AND ANTENNA DIAMETER ON FREQUENCY SELECTIVE MULTIPATH FADING

Paje, Vladimir I. 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper uses ARTM channel sounding data collected at Edwards Air Force Base to investigate the dependency between the characteristics of frequency selective multipath fading and carrier frequency and ground based received antenna diameter. Channel model parameters are obtained from data sets measured at different frequencies and various ground based antenna diameters. The analysis shows that the multipath characteristics do not statistically change between the L-band and S-band carrier frequencies, but do change with antenna diameter. Furthermore, Flight 18 data shows that antenna diversity may be a useful technique to reduce data loss from multipath fading.
7

DYNAMIC BEHAVIOR OF MULTIPATH INTERFERENCE IN ARTM CHANNEL SOUNDING DATA

Davis, Adam Todd 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Data collected during July 1999 at Edwards EAFB by the Advanced Range Telemetry (ARTM) program is examined to characterize the dynamic behavior of multipath interference in an aeronautical telemetry channel. Multipath fade events are analyzed in the frequency domain to show how these fades appear, evolve, and disappear from the channel. A channel model and examples from the channel sounding data are used to show the dynamic nature of these fade events. The Doppler power spectrum is used to quantify the exact time-varying nature of the multipath fade events. The coherence time, or the amount of time the channel can be viewed as unchanging, is obtained from the Doppler power spectrum and is calculated to be 100 ms in the data sets examined in this paper. This implies that adaptive multipath mitigation techniques must have an adaptation bandwidth of 10 Hz.
8

A Sliding Correlator Channel Sounder for Ultra-Wideband Measurements

Pirkl, Ryan Jesse 29 June 2007 (has links)
This body of work forms a detailed and comprehensive guide for those interested in performing broadband wireless channel measurements. Discussion addresses the theoretical and practical aspects of designing and implementing a sliding correlator channel sounder, as well as how such a system may be used to measure and model the ultra-wideband wireless channel. The specific contributions of this work are as follows: Developed a systematic methodology for designing optimal sliding correlator-based channel sounders. Constructed a UWB channel sounder based upon a 17-bit LFSR that attained 1.66 ns of temporal resolution and 34 dB of dynamic range. Performed an exemplary measurement campaign of the UWB channel from which UWB angular spreads and RMS delay spreads are reported. The design procedure developed in Chapter 3 will allow researchers to build optimal channel sounders for investigating next-generation wireless channels. Chapter 4 s discussion addresses the real-world challenges of constructing a high performance sliding correlator channel sounder. Finally, the measurement campaign discussed in Chapter 5 outlines a procedure for investigating the spatio-temporal characteristics of the wireless channel and provides some of the first examples of UWB angular spread measurements.
9

Characterization and Evaluation of Non-Line-of-Sight Paths for Fixed Broadband Wireless Communications

Gallagher, Timothy M. 02 July 2004 (has links)
Channel impulse responses collected on the Virginia Tech campus show combinations of specular multipath and diffuse scattering at LMDS frequencies. An algorithm is presented that estimates link performance based on the channel impulse response. Presented and analyzed are representative impulse responses (one is primarily specular in nature and one shows significant diffuse scattering) to show that the proposed algorithm is appropriate for analyzing channels exhibiting either of these characteristics. Monte Carlo simulations logged the sequence number of each bit error to gain an understanding of the distribution of errors over time. The results show that for these static channels the errors occur randomly rather than in bursts, leading to the conclusion that average bit-error rate statistics are appropriate for channel characterization. Zero-Forcing (Z-F) and Minimum Mean Square Error (MMSE) equalizers employed on these channels had a significant impact on the link quality. In many cases, the performance of the MMSE equalizer performed only slightly better than the Z-F equalizer. However, when deep nulls were present in the channel response, the MMSE equalizer performed significantly better. Algorithms for determining the number of taps necessary to approach an optimum equalization are presented for both types of equalizers and a '98%' rule of thumb is presented. The algorithm's role in adaptive and cognitive radio systems is discussed and two applications are presented to illustrate its utility. / Ph. D.
10

Cellular and peer-to-peer millimeter wave channel sounding in outdoor urban environments

Ben-Dor, Eshar 17 February 2012 (has links)
Millimeter wave (mm-Wave) systems have become very attractive recently as lower frequency spectrums used for mobile device communications have been experiencing a “spectral crunch” due to the dissemination of smartphones. Channel characterization of the outdoor urban environment, where networks for mobile devices require the highest data capacity, has been quite scarce and even non-existent for cellular (rooftop to ground) setting measurements. Our project characterizes the urban environment at 38 GHz in a cellular setting and 38 and 60 GHz in a peer-to-peer setting. A sliding correlator channel sounder with an 800 MHz RF bandwidth at 38 GHz and 1.5 GHz RF bandwidth at 60 GHz was constructed to measure the channel using a bandwidth that is larger than the expected bandwidths of future mm-Wave channels. Directional antennas were utilized during the measurements to imitate mm-Wave systems using beam steering antenna arrays, which also allowed for AOA characterization. Path loss and RMS delay spread statistics are provided. Finally, an outage study was performed to test the outage likelihood in an urban environment with many multi-story buildings. / text

Page generated in 0.0906 seconds