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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.
1

Implantable Functional Electrical Micro-Stimulation System

Hsiao, Yu-Tzu 13 July 2004 (has links)
For several decades of years, the electrical stimulation has been applied on rehabilitation of motional recovery for quadriplegic and paraplegic patients such as walking, standing, and cycling exercise. As the advancement of VLSI (very large scale integration) technology, the implantable micro-stimulators become feasible in recent years. This thesis presents an implantable system including an inductively coupling transceiver of power & data, a protocol of communication, and the implementation of a FES (Functional Electrical Stimulation ) SOC (System-On-chip). The first part of this thesis discusses the architecture of the proposed implantable FES system, including the theory of wireless power transmission, the implementation of mixed-signal circuits, the RS232 protocol, and two encoding methods of Manchester code and NRZ code. The second part of this thesis is focused on the multi-frequency stimulation of the implantable FES system, which comprises an advanced communication protocol suitable for multi-frequency stimulation function and a novel arrangement of interconnections for the chip.
2

Διερεύνηση ασύρματης μετάδοσης δεδομένων και εφαρμογή στην βιοϊατρική

Κουρής, Ιωάννης 19 January 2009 (has links)
Η ασύρματη μετάδοση δεδομένων τηλεϊατρικής καθιστά ένα εύρος μετρήσεων που θα έπρεπε να έχουν καθηλωμένο τον ασθενή, να γίνεται εύκολα και απομακρυσμένα. Στην παρούσα εργασία γίνεται διερεύνηση των δυνατοτήτων που προσφέρει η ασύρματη μετάδοση τηλεϊατρικών δεδομένων και ειδικότερα το πρωτόκολλο IEEE 802.15.4, το οποίο εντάσσεται στα ασύρματα δίκτυα χαμηλής ισχύος. Το πρωτόκολλο αυτό υποστηρίζει χαμηλό ρυθμό μετάδοσης δεδομένων, ικανό όμως για τη μετάδοση βιολογικών δεδομένων, έχει χαμηλή κατανάλωση ισχύος, είναι χαμηλού κόστους και έχει μια εμβέλεια 10 έως 75 μέτρα. Παράλληλα με τη διερεύνηση των δυνατοτήτων του συγκεκριμένου πρωτοκόλλου στην μετάδοση βιολογικών δεδομένων γίνεται και υλοποίηση σε hardware ενός συστήματος συγκέντρωσης και μετάδοσης των δεδομένων με το πρωτόκολλο IEEE 802.15.4. / The wireless data transmission in telemedicine makes a range of measurements that should have riveted the patient, easily and remotely. In the present work is exploring the possibilities to offer wireless telemedical data transmission and in particular Protocol IEEE 802.15.4, Zigbee. This protocol supports low data transmission rates, but able to transmit biological data. Alongside exploring the possibilities of the transmission protocol to biological data and is a hardware implementation of a system gathering and data transmission protocol with IEEE 802.15.4.
3

Prototype system for detecting and processing of IEEE 802.11a signals

Goh, Che Seng 03 1900 (has links)
Approved for public release, distribution is unlimited / As the need to send larger amounts of information increases, the military is looking into viable solutions to push this information throughout the battle space. IEEE 802.11a wireless LAN network presents an attractive high-speed solution by providing data rates up to 54 Mbps. At the same time, wireless LAN introduces increased security risk due to its vulnerability to exploitation of the wireless LAN physical layer. This research will develop a prototype system using low cost hardware and software solution to detect and process wireless IEEE 802.11a signals. Using the prototype, performance data will be collected to determine whether IEEE 802.11a is a feasible option as a high-speed information network for military use. Additionally, the performance data collected will provide a good basis for predicting the expected performance in an operational scenario and provide valuable information for proper deployment planning. / Major, Republic of Singapore Air Force
4

Bezdrátový přenos letových údajů z letounu na krátkou vzdálenost / Wireless transmission of flight data for low distance

Kučera, Petr January 2009 (has links)
This diploma thesis deals with the flight data wireless transmission from aircraft to the ground station. This is the data sent from the acrobatic aircraft during races, specifically the GPS position and data from sensors of acceleration and rotation of the aircraft. It dealt with the theoretical analysis of the radio link and design of device that receives radio transmission. In aircraft it is dealt with data capturing and their deployment through the radio module. Data are sending to another post-processing on the ground station after receiving. There are two solutions of radio module and in the last part is a solution for capturing data from more airplanes.
5

Residential Microwave Oven Interference on Bluetooth Data Performance

D'Souza, Mark Francis 19 May 2003 (has links)
This thesis investigates the interference potential of microwave ovens to Bluetooth data communication. Interference experiments are conducted in the CWT's Bluetooth lab, using CSR™ (Cambridge Silicone Radio) Bluetooth radios and a Tektronics™ Protocol Analyzer to record packet transmissions between the master and slave units. A novel, "quasi-real time" spectral measurement concept is developed to take radio frequency measurements. A LabView program enables a spectrum analyzer to download oven spectral data onto a computer via the instrument's serial port. From this data, three-dimensional plots of microwave radiated power levels versus ISM band frequencies over time periods are produced for different microwave ovens. These plots are compared with the results of interference experiments to explain Bluetooth packet errors. In addition to causing packet errors, emitted oven power levels at certain frequencies are sometimes strong enough to cause data packets to be lost (dropped) as they are transmitted over the air. This is a major problem since the Protocol Analyzer does not "see" these packets and cannot record the transmissions during an experiment. These lost packets can be accounted for if the frequency hopping scheme of the communicating Bluetooth devices is know prior to data transmission. Bluetooth's Frequency Hop Scheme is coded in Matlab for the purpose of predicting a data transmission's hopping sequence. The lost packets on each Bluetooth channel are counted by subtracting the Analyzer's recorded number of data transmissions per channel from the total number of transmissions per channel predicted by Matlab. A method is devised to calibrate the Bluetooth receiver and the spectrum analyzer is used to measure the received power level of Bluetooth signals on a particular frequency (channel). The number of packet errors on a channel is determined from the channel's C/I (carrier-to-interference ratio). If a channel's C/I level falls below the calculated C/I threshold at any instant of time due to oven operation, the packet transmitted at that instant is likely in error. A Matlab program estimates the number of packet errors per channel by counting the number of times the C/I of a channel falls below it's threshold value. The predicted number of packet errors is compared with the measured packet errors from experiments to yield extremely good results. Various oven-interference experiments are conducted in a small building, a large office environment and outdoors. For each experiment, the number of occurrences of transmitted data is plotted for each Bluetooth channel. Composite Excel bar graphs, created from this data, are compared with the oven spectral plots to describe an oven's effect on Bluetooth transmission. It is determined that different ovens cause packet errors on specifically different channels, in addition to channels 52-54 around the oven's 2450 MHz center operating frequency. The interference experiments suggest that placing an oven a radius of 10 m away from Class I (devices in a piconet will not affect data transmission). / Master of Science
6

Non-radiative resonant wireless energy transfer

2013 April 1900 (has links)
This thesis describes a theoretical and experimental investigation of wireless energy transfer between high-Q resonant radiofrequency (RF) oscillators. A model used by Kurs \emph{et al} \cite{Kurs_original} was recast in a form which enabled expression of the results in terms of measurable electrical quantities. This model was tested using circular resonant copper loop antennas at a frequency near 10 MHz. Accurate calculation of the mutual inductance between loops was required in order to predict the loop coupling parameters, and was carried out using a custom-written computer code. Two resonant loop antenna RF oscillators were first used to check that the model predictions were accurate in the two-oscillator case. Based on the success of these tests, the model was extended to the case of three oscillators in two different configurations, the first having two receiving oscillators, and the second having two transmitting oscillators. Model predictions for both configurations were experimentally tested over a range of coil separations and angular inclinations. These experimental tests confirmed the model's applicability in the three-oscillator regime, with significant deviations from the model only being observed when any pair of loops was in very close proximity (i.e. when the separation of loop centers was comparable to the loop diameter). This may have been be due to either nonlinear dielectric losses (due to large amplitude RF electric fields) spoiling the Quality factors Q of the loop antenna resonators, or to increased capacitive coupling between loops at short distances (not included in the current model), or both. Further investigation would be required to definitively establish the origin of the deviation from the model at short distances, but from an engineering point of view accurate modelling of the performance in the "close loop" regime is not critical since the primary purpose of wireless power transfer is to transmit power over a reasonable distance.
7

Bezdrátový přenos výkonu / Wireless transfer of energy

Varga, David January 2011 (has links)
ork tie together on first project, in which the was designed apparatus for tests wireless transmission energy. Antenna was synthesized and theoretically optimized for experimental operation, in which the will performed series measuring. In first part is practical description of realization proposal. It consists of circuital solution, proposal measuring workplace and mechanical construction with illustration photographs of arrangement. Second part includes results of performed measuring. These measuring will divided by three basic groups: in first group will by testing feature one’s antennae, in second group will series transmission measuring power gain, and in third group will photographed shape of field, and comparison with simple simulation finite difference method. Third part summarises results from measuring, and prepares consecutive balancing visualisation project, which is of thematic bent on chosen aspects theoretical hypothesis and effected experiments.
8

Digitální bezdrátový přenos zvukového signálu / Digital audio wireless transmission

Juráň, Jeroným January 2017 (has links)
This document describes the design of evaluation boards for wireless transmission of audio signal. The boards use WiSA compliant modules. It describes schematics of transmitter board, receiver board and boards of both AD and DA converter. Secondly the document describes the designed PCBs and demonstrates the results by photodocumentation. It also includes description of C library for using FLASH memory to store data and the C driver for FT800 chip and the typical application using this chip including touch
9

Performance analysis of Point-to-Multi-Point (P2MP) Hybrid FSO/RF network

Boharba, Alwa Mohamed 05 May 2020 (has links)
In this thesis, we present a detailed analysis of hybrid point-to-multipoint free space optical (FSO)/radio frequency (RF) wireless system. Hybrid FSO/RF sys- tems have emerged as a promising solution for high data rate wireless transmission. FSO technology can be used effectively in multiuser scenarios to support Point-to- Multi-Point (P2MP) networks. In this P2MP network, FSO links are used for data transmission from a central location to multiple users. When more than one FSO link fail, the central node uses a common backup RF link to transmit a frame to a remote node using an equal priority protocol. An equal priority protocol means that the remote nodes have the same priorities in being assigned the RF link. We assume two traffic classes, a high-priority and low-priority classes. The base station reserves two transmit buffers of each user for the downlink transmission. Considering the downlink traffic from the base station to a tagged remote node, we study several performance metrics. We develop a cross-layer Markov chain model to study the throughput from central node to a remote node as well as the performance of the resulting system. / Graduate
10

Study of wireless transmission protocol technology for use in flight line environment to assist the data uploading and downloading on aircraft

Meng, Ow Keong 03 1900 (has links)
Approved for public release, distribution is unlimited / Presently, the required data file to be loaded onto the Radar Warning Receiver (RWR) onboard the F-16 aircraft is done manually by the aircraft technicians, two to three hours prior to the actual flight time. This process should be automated. As such there is a need to look into the use of wireless transmission technology to complement or replace the manual method of loading the critical data file from the command station onto every F-16 aircraft. The present wireless technology is relatively mature and stable. In this thesis, the feasibility of incorporating and adapting this technology for use in the flight line environment is examined. The propagation effect in wireless transmission is also studied and recommendations proposed with regards to the installation of wireless facilities in the flight line. In addition, the EDNA, a portable maintenance aid that comes with the F-16 aircraft for loading the data file, has to be upgraded. Hence, a system feasibility study is carried out to adapt or upgrade the present equipment to wireless transmission capability. / Major, Republic of Singapore Air Force

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