This thesis describes an intelligent underwater acoustic system that allows the positions of several divers or Remotely Operated Vehicles (ROV) to be tracked in three-dimensional space and to telemeter the co-ordinates to a remote receiver at the surface. The positions are fixed using three randomly deployed seabed transponders that may be described as intelligent. The transponders fix their own relative positions and the position of the surface receiver, usually a vessel, by an exchange of coded acoustic pulses. These positions can be related to a differential GPS system at the surface if absolute coordinates are required. An underwater acoustic positioning and communication system can provide a vital navigation aid for a diver and surface supervisor. Often underwater positioning systems only provide the surface supervisor with diver's positions, with the diver navigating from voiced instruction via an acoustic or wire link communication. In the system described the divers each know their own position from a wrist-worn computer with a backlit graphical/numerical display. As well as the current position, the display can show the track from the beginning of the dive, the location of the surface vessel and the instantaneous position of the other divers.

CIVINS / This thesis presents a simulation of autonomous underwater vehicle navigation using a single transponder to create a virtual long baseline (VLBL). Similarly to LBL systems, ranges in a VLBL are calculated between the vehicle and the transponder, but the vehicle position is determined by advancing multiple ranges from a single transponder along the vehicles dead reckoning track. Vehicle position is then triangulated using these successive ranges in a manner analogous to a 'running fix' in surface ship navigation. Navigation data from bottom survey operations of an underwater vehicle called the Autonomous Benthic Explorer (ABE) were used in the simulation. The results of this simulation are presented along with a discussion of the benefits, limitations, and implications of its extension to real-time operations. A cost savings analysis was also conducted based both on the idea that a single surveyed beacon could be deployed for underwater navigation and on the further extension of this problem that the 'single beacon' used for navigation could be located on the ship itself. / Contract number: N62271-97-G-0026. / CIVINS / US Navy (USN) author.

Thesis (Ph. D.)--Dept. of Engineering, University of Adelaide, 1984. / Some mounted ill. Includes bibliographical references.

Project report (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Abstract. Includes bibliographical references (leaves 68-70). Also available via the Internet.

Some mounted ill. / Includes bibliography / xii, [468] leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Dept. of Engineering, University of Adelaide, 1984

Thesis (M.S.)--Michigan State University. School of Packaging, 2006. / Title from PDF t.p. (viewed on Nov. 17, 2008) Includes bibliographical references (p. 219-223). Also issued in print.

Chan, Chi Fat. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract --- p.2 / 摘要 --- p.5 / Acknowledgement --- p.7 / Table of Contents --- p.9 / List of Figures --- p.11 / List of Tables --- p.14 / Chapter 1. --- Introduction --- p.15 / Chapter 1.2. --- Research Objectives --- p.16 / Chapter 1.3. --- Thesis Organization --- p.18 / Chapter 1.4. --- References --- p.19 / Chapter 2. --- Overview of Passive UHF RFID Transponders --- p.20 / Chapter 2.1. --- Types of RFID Transponders and Design Challenges of Passive RFID Transponder --- p.20 / Chapter 2.2. --- Selection of Carrier Frequency --- p.22 / Chapter 2.3. --- Description of Transponder Construction --- p.22 / Chapter 2.3.1. --- Power-Generating Circuits --- p.23 / Chapter 2.3.2. --- Base Band Processor --- p.28 / Chapter 2.3.3. --- Signal Front-End --- p.29 / Chapter 2.4. --- Summary --- p.30 / Chapter 2.5. --- References --- p.31 / Chapter 3. --- ASK Demodulator for EPC C-l G-2 Transponder --- p.32 / Chapter 3.1. --- ASK Demodulator Design Considerations --- p.32 / Chapter 3.1.1. --- Recovered Envelope Distortion --- p.32 / Chapter 3.1.2. --- Input Power Level Considerations --- p.34 / Chapter 3.1.3. --- Input RF power Intercepted by ASK Demodulator --- p.36 / Chapter 3.2. --- ASK Demodulator Design From [3-4] --- p.36 / Chapter 3.2.1. --- Envelope Waveform Recovery Design --- p.37 / Chapter 3.2.1.1. --- Voltage Multiplier Branch for Generating Venv --- p.39 / Chapter 3.2.1.2. --- Voltage Multiplier Branch for Generating Vref --- p.41 / Chapter 3.2.2. --- Design Considerations for Sensitivity of ASK Demodulator --- p.41 / Chapter 3.2.3. --- RF Input Power Sharing with Voltage Multiplier --- p.44 / Chapter 3.2.4. --- ASK Demodulator and Voltage Multiplier Integrated Estimations for Maximum RF Power Input --- p.47 / Chapter 3.2.5. --- Measurement result and Discussion --- p.49 / Chapter 3.3. --- Proposed Envelope Detector Circuit --- p.52 / Chapter 3.3.1. --- Sensitivity Estimation --- p.52 / Chapter 3.3.2. --- Maximum Tolerable Input Power Estimation --- p.53 / Chapter 3.3.3. --- Envelope Waveform Recovery of the Proposed Envelope Detector --- p.54 / Chapter 3.4. --- Summary --- p.57 / Chapter 3.5. --- References --- p.58 / Chapter 4. --- Clock Generator for EPC C-l G-2 Transponder --- p.59 / Chapter 4.1. --- Design Challenges Overview of Clock Generator --- p.59 / Chapter 4.2. --- Brief Review of PIE Symbols in EPC C1G2 Standard --- p.62 / Chapter 4.3. --- Proposed Clock Recovery Circuit Based on PIE Symbols for Clock Frequency Calibration --- p.64 / Chapter 4.3.1. --- Illustration on PIE Symbols for Clock Frequency Calibration --- p.64 / Chapter 4.3.2. --- Symbol time-length counter --- p.72 / Chapter 4.3.3. --- The M2.56MHZ Reference Generator and Sampling Frequency Requirement --- p.75 / Chapter 4.3.4. --- Symbol Length Reconfiguration for Different Tari and FLL Stability --- p.80 / Chapter 4.3.5. --- Frequency Detector and Loop Filter --- p.83 / Chapter 4.3.6. --- Proposed DCO Design --- p.84 / Chapter 4.3.7. --- Measurement Results and Discussions --- p.88 / Chapter 4.3.7.1. --- Frequency Calibration Measurement Results --- p.89 / Chapter 4.3.7.2. --- Number x and Tari Variation --- p.92 / Chapter 4.3.7.3. --- Temperature and Supply Variation --- p.93 / Chapter 4.3.7.4. --- Transient Supply Variation --- p.94 / Chapter 4.3.8. --- Works Comparison --- p.95 / Chapter 4.4. --- Clock Generator with Embedded PIE Decoder --- p.96 / Chapter 4.4.1. --- Clock Generator for Transponder Review --- p.96 / Chapter 4.4.2. --- PIE Decoder Review --- p.97 / Chapter 4.4.3. --- Proposed Clock Generator with Embedded PIE Decoder --- p.97 / Chapter 4.4.4. --- Measurement Results and Discussions --- p.100 / Chapter 4.5. --- Summary --- p.103 / Chapter 4.6. --- References --- p.105 / Chapter 5. --- ASK Modulator --- p.107 / Chapter 5.1. --- Introduction to ASK Modulator in RFD Transponder --- p.107 / Chapter 5.2. --- ASK Modulator Design --- p.109 / Chapter 5.3. --- ASK Modulator Measurement --- p.110 / Chapter 5.4. --- Summary --- p.113 / Chapter 5.5. --- References --- p.113 / Chapter 6. --- Conclusions --- p.114 / Chapter 6.1. --- Contribution --- p.114 / Chapter 6.2. --- Future Development --- p.116

A transponder for underwater acoustic data communications is prototyped. The mobile transponder emits a data sequence whenever it detects a ping from a base station. The data sequence includes GPS coordinates and UTC time sent over a conservative and brief 12 kbps turbo-coded BPSK link, and a 6 kB JPEG image sent over an ambitious 67 kbps turbo-coded 16-QAM link. The range of the transponder from the base station can also be accurately derived. Several challenges exist in decoding the underwater signals at the base station receiver, including Doppler distortion and multipath. While experimental results show that the ranges for decoding the 16-QAM signals with a single hydrophone are limited to less than 25 m, the BPSK signals prove to be much more robust, decoding at ranges of up to 625 m. Experiments with delays and transducer tether length indicate methods for improving reliability in the presence of reverberation and thermocline. This transponder uses mostly off-the-shelf parts and is anticipated to be improved when paired with advanced sonar array devices. / text

This report describes an assessment of using dedicated short-range communications(DSRC) technology to perform travel time monitoring and automated incident detectionon a segment of rural freeway. The assessment used the CORSIM traffic simulation toolto simulate traffic and incidents on a segment of rural freeway. Output data from thesimulation was subjected to post-processing to produce the "probe and beacon" data thatwould be produced by a DSRC-based system. An incident detection algorithm wasdeveloped, which used a travel time threshold and a counter. Travel times exceeding thethreshold incremented the counter, while travel times below the threshold decrementedthe counter (unless it was at zero). An alarm was generated when the counter reached apre-selected level. This algorithm was tested on selected data files, and the results wereused to identify the "best" values of the threshold and counter alarm level. Using these"best" values, the algorithm was then applied to the "probe and beacon" data todetermine how quickly the system could detect various traffic incidents. The analysisshowed that the system could provide rapid and reliable detection of incidents.During the simulation and analysis, several parameters were varied to observe theirimpacts on the system performance. These parameters included traffic volume, incidentseverity, percentage of vehicles with transponders, spacing of roadside readers, andlocation of the incident relative to the next downstream reader. Each parameter proved tohave a significant effect on the detection time, and the observed impacts were consistentwith logical expectations. In general, the time to detect an incident was reduced inresponse to (1) an increase in traffic volume, (2) an increase in incident severity, (3) anincrease in transponder population, (4) a reduction in reader spacing, and (5) a reductionin distance from incident location to next downstream reader.Preliminary estimates were developed of the costs associated with implementing aDSRC-based traffic monitoring system. The relationship between system cost andsystem performance was explored and illustrated.Recommendations were developed and presented. These included further analysis basedon traffic simulations, followed by a limited field deployment to validate the analysisresults.

Thesis (M.S.)--Joint Program in Oceanography/ Applied Ocean Science and Engineering, Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 2005. / Bibliography: p.124-125.