Current Search: Bagby, Jonathan S. (x)
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(1 - 8 of 8)
- Title
- Acceleration charge sensitivity in AT-quartz resonators.
- Creator
- Anderson, Clifford L. H., Florida Atlantic University, Bagby, Jonathan S.
- Abstract/Description
-
The behavior of AT-quartz resonators subject to acceleration is studied. For an AT strip resonator with cantilever mounting, piezoelectric theory predicts that excitation of the pure lowest frequency flexural mode of vibration generates no charge. However, experiments show electromechanical resonance corresponding to this mode for sinusoidal support motion normal to the plane of the crystal with no applied electric field. An amplifier with a voltage follower first stage senses charge output...
Show moreThe behavior of AT-quartz resonators subject to acceleration is studied. For an AT strip resonator with cantilever mounting, piezoelectric theory predicts that excitation of the pure lowest frequency flexural mode of vibration generates no charge. However, experiments show electromechanical resonance corresponding to this mode for sinusoidal support motion normal to the plane of the crystal with no applied electric field. An amplifier with a voltage follower first stage senses charge output from the crystal. Shielding is required to reduce sixty hertz and drive frequency electromagnetic interference. Measurement of resonant frequency and damping factor for the lowest frequency flexural mode is reported for a group of 17.76 MHz oscillator crystals. This mode is responsible for crystal breakage in some portable communications products. Significant variation in sensitivity among crystals was observed. Charge sensitivity of this mode is attributed in part to mechanical coupling to other modes involving torsion and lateral flexure.
Show less - Date Issued
- 1995
- PURL
- http://purl.flvc.org/fcla/dt/15126
- Subject Headings
- Quartz crystals, Piezoelectricity, Oscillators, Crystal, Resonators, Acceleration (Mechanics)
- Format
- Document (PDF)
- Title
- Design ofMOSFET ultra-wideband low noise amplifiers.
- Creator
- Camacho, Esteban, Bagby, Jonathan S., Florida Atlantic University
- Abstract/Description
-
Ultra-Wide band (UWB) systems are a new wireless technology capable of transmitting data over a wide spectrum of frequency bands with very low power and high data rates. This technology has the potential to replace almost every cable at home or in an office with a wireless connection. In a UWB receiver, a radio frequency (RF) low noise amplifier (LNA) is one of the most important components. This thesis discusses the entire process involving the design ofUWB low noise amplifiers including a...
Show moreUltra-Wide band (UWB) systems are a new wireless technology capable of transmitting data over a wide spectrum of frequency bands with very low power and high data rates. This technology has the potential to replace almost every cable at home or in an office with a wireless connection. In a UWB receiver, a radio frequency (RF) low noise amplifier (LNA) is one of the most important components. This thesis discusses the entire process involving the design ofUWB low noise amplifiers including a detailed stage by stage analysis of a computer aided design (CAD) of a MOSFET UWB LNA. Simulation tools and concepts from Level I equations are used in order to design a circuit with a realistic MOS model such as the BSIM3 used in this work. The LNA shows improved power consumption over the designs it is based on while still producing comparable results.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/fau/fd/FA00012510
- Subject Headings
- Electronic circuit design, Integrated circuits--Very large scale integration, Metal-oxide semiconductor field-effect transistors--Design, Power transistors--Design
- Format
- Document (PDF)
- Title
- Theory of and a novel approach to high-stability frequency control circuits.
- Creator
- Brunell, David J., Florida Atlantic University, Bagby, Jonathan S.
- Abstract/Description
-
Portable, wireless devices have become ubiquitous, and ever-increasing requirements of functionality and reliability are being placed upon these devices. There is a need to accommodate the oft-conflicting requirements of small size, low power consumption, low cost, and extremely accurate control of frequency. To address these RF design requirements, a comprehensive survey of existing frequency-control methods is presented, followed by a novel design which accomplishes a high degree of...
Show morePortable, wireless devices have become ubiquitous, and ever-increasing requirements of functionality and reliability are being placed upon these devices. There is a need to accommodate the oft-conflicting requirements of small size, low power consumption, low cost, and extremely accurate control of frequency. To address these RF design requirements, a comprehensive survey of existing frequency-control methods is presented, followed by a novel design which accomplishes a high degree of frequency accuracy through the use of direct digital synthesis and a software seeking algorithm. The proposed design can be implemented pursuant to the requirements of current and future portable wireless devices.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12819
- Subject Headings
- Frequency synthesizers, Automatic frequency control, Oscillators, Crystal
- Format
- Document (PDF)
- Title
- Analysis and design of simulated human bodies using the finite difference time domain method.
- Creator
- Napoles, Adrian., Florida Atlantic University, Bagby, Jonathan S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
A three-dimensional finite difference time domain analysis of a saline water phantom used in industry for testing body-mounted receivers is presented. Specifically, a saline water phantom known as "Salty" is analyzed. Salty is an acrylic circular cylinder which is filled with a saline solution. The fields at the center of the cylinder and 1 cm external to the surface of the cylinder are obtained with the FDTD method for normally incident TMz and TEz plane wave excitation in free space. The...
Show moreA three-dimensional finite difference time domain analysis of a saline water phantom used in industry for testing body-mounted receivers is presented. Specifically, a saline water phantom known as "Salty" is analyzed. Salty is an acrylic circular cylinder which is filled with a saline solution. The fields at the center of the cylinder and 1 cm external to the surface of the cylinder are obtained with the FDTD method for normally incident TMz and TEz plane wave excitation in free space. The results from the FDTD simulation are then compared to the closed-form solution, which is obtained by assuming that Salty is infinitely long. A low dielectric constant simulated human body which emulates the performance of Salty is designed using the closed-form solution for the near fields of a two-layer cylinder and its performance is verified with the FDTD method.
Show less - Date Issued
- 1995
- PURL
- http://purl.flvc.org/fcla/dt/15215
- Subject Headings
- Time-domain analysis, Beepers (Pagers), Electromagnetic waves--Scattering--Mathematical models
- Format
- Document (PDF)
- Title
- Application of MoM: Scattering calculations using condition number.
- Creator
- Zhuang, Zhijun., Florida Atlantic University, Bagby, Jonathan S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
Computational accuracy is widely recognized as a critical issue in applied electromagnetics. Increasing computational power is being applied to solve more complex electromagnetic systems with an emphasis on computational accuracy. The work of this thesis is focused on the implementation of Method of Moments (MoM) to integral equation formulations. The goal of this effort is to use what is known as condition number, and, a heuristic rule-of-thumb is applied to investigate the computational...
Show moreComputational accuracy is widely recognized as a critical issue in applied electromagnetics. Increasing computational power is being applied to solve more complex electromagnetic systems with an emphasis on computational accuracy. The work of this thesis is focused on the implementation of Method of Moments (MoM) to integral equation formulations. The goal of this effort is to use what is known as condition number, and, a heuristic rule-of-thumb is applied to investigate the computational accuracy of MoM in numerical electromagnetics. Other possible applications of condition number of the MoM matrix are also indicated.
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/15719
- Subject Headings
- Electromagnetism, Moments method (Statistics), Electromagnetic theory, Integral equations--Numerical solutions
- Format
- Document (PDF)
- Title
- Performance of multicarrier DS CDMA systems in a Nakagami fading channel.
- Creator
- Wang, Jifang., Florida Atlantic University, Bagby, Jonathan S., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
The performance of a multicarrier DS CDMA system is evaluated over a Nakagami multipath fading channel. After the spreading process, the data sequence is applied to multiple carrier rather than a single carrier. Each carrier is provided a corralator in the receiver, and the maximal-ratio combiner is used for the corralator outputs. A bandlimited spreading waveforms are used for self-interference prevention. Robustness to multipath fading and narrow band interference suppression are achieved...
Show moreThe performance of a multicarrier DS CDMA system is evaluated over a Nakagami multipath fading channel. After the spreading process, the data sequence is applied to multiple carrier rather than a single carrier. Each carrier is provided a corralator in the receiver, and the maximal-ratio combiner is used for the corralator outputs. A bandlimited spreading waveforms are used for self-interference prevention. Robustness to multipath fading and narrow band interference suppression are achieved by this type of configuration. A comparison is made with a single carrier system in the presence of interference.
Show less - Date Issued
- 1998
- PURL
- http://purl.flvc.org/fcla/dt/15534
- Subject Headings
- Code division multiple access, Wireless communication systems, Radio--Transmitters and transmission--Fading
- Format
- Document (PDF)
- Title
- Passive Optical Networks with a New Bandwidth Allocation Scheme in Ethernet Passive Optical Networks.
- Creator
- Krijestorac, Sadeta, Bagby, Jonathan S., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
With the ever increasing demand for bandwidth intensive applications like video-ondemand, interactive television services, high-defmition television (HDTV) and internet telephony, the first mile network, referred to as the last mile network in the earlier stages of its development, has proven to solve the "bottleneck" often experienced between users and the central office. The Ethernet Passive Optical Network (EPON), developed by the IEEE 802.3ah Task Force for Ethernet in the First Mile (EFM...
Show moreWith the ever increasing demand for bandwidth intensive applications like video-ondemand, interactive television services, high-defmition television (HDTV) and internet telephony, the first mile network, referred to as the last mile network in the earlier stages of its development, has proven to solve the "bottleneck" often experienced between users and the central office. The Ethernet Passive Optical Network (EPON), developed by the IEEE 802.3ah Task Force for Ethernet in the First Mile (EFM), resolves this bottleneck by providing the user with a fiber optic link to the central office that has many advantages, such as nearly infinite bandwidth, low cost, easy installation and immunity to electromagnetic interference, and a saving of the need for powered components in the signal path from the user to the switch. EPON s have proven to deliver the essential services of voice, video, and data communications reliably, while at the same time providing expected guarantees of the delivery of those services in terms of defined Quality of Service measures (QOS). A continuous theme throughout EPON research has been the study of efficient Dynamic Bandwidth Allocation (DBA) as a key factor in achieving fairness in distributing bandwidth amongst remote network units. This research investigates another factor and its effect on network performance and service delivery: Cycle Demand Proportionality (CDP). By observing the patterns of demand in the network on an individual network unit basis cycle after cycle, deductions regarding load characteristics of some units over others can be made. Decisions can be make about subsequent grant allocations based on this factor and aim to achieve better results in the process. Simulations of EPONs Lmder varying loads incorporating the usc of CDP in conjunction with currently used DBA schemes are made and results are analyzed. A major contribution of this research is a new bandwidth allocation algorithm that gives improved performance in terms of packet delay versus offered load. Performance metrics are compared against two common bandwidth allocation algorithms: Interleaved Polling with Adaptive Cycle Time (IPACT) and Cyclic Polling (CP). Additional results also include improvements in packet loss and throughput. The data that represents traffic for this network has two properties, self-similarity and long range dependency. Plotting the auto-covariance, auto-correlation, and variance for this traffic, for various aggregation levels demonstrates these properties.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/fau/fd/FA00012571
- Subject Headings
- Ethernet (Local area network system), Optical communications, Computer network protocols, Wavelength divisional multiplexing
- Format
- Document (PDF)
- Title
- Effects of Adaptive Antenna Array Beamforming and Power Management with Antenna Element Selection.
- Creator
- Abazari Aghdam, Sajjad, Bagby, Jonathan S., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
This research is the array processing help wireless communication techniques to increase the signal accuracy. This technique has an important part of prevalent applications. The wireless communication system, radar, and sonar. Beamforming is one of methods in array processing that filters signals based on their capture time at each element in an array of antennas spatially. Numerous studies in adaptive array processing have been proposed in the last several decades, which are divided in two...
Show moreThis research is the array processing help wireless communication techniques to increase the signal accuracy. This technique has an important part of prevalent applications. The wireless communication system, radar, and sonar. Beamforming is one of methods in array processing that filters signals based on their capture time at each element in an array of antennas spatially. Numerous studies in adaptive array processing have been proposed in the last several decades, which are divided in two parts. The first one related to non-adaptive beamforming techniques and the next one related to digitally adaptive Beamforming methods. The trade-off between computational complexity and performance make them different. In this thesis, we concentrate on the expansion of array processing algorithms in both non-adaptive and adaptive ones with application of beamforming in 4G mobile antenna and radar systems. The conventional and generalized side-lobe canceller (GSC) structures beamforming algorithms were employed with a phase array antenna that changed the phase of arrivals in array antenna with common phased array structure antennas. An eight-element uniform linear array (ULA), consisting of di-pole antennas, represented as the antenna array. An anechoic chamber measures the operation of beamforming algorithms performance. An extended modified Kaiser weighting function is proposed to make a semi-adaptive structure in phased array beamforming. This technique is extended to low complexity functions like hyperbolic cosine and exponential functions. Furthermore, these algorithms are used in GSC beamforming. The side-lobe levels were so lower than other algorithms in conventional beamforming around -10 dB. On the other hand, a uniform linear arrays for smart antenna purposes designed to utilize in implementing and testing the proposed algorithms. In this thesis, performance of smart antenna with rectangular aperture coupled microstrip linear array which experimental investigations carried out for obtaining X-band operation of rectangular microstrip antenna by using aperture coupled feeding technique. Frequency range set at approximately 8.6 to 10.9 GHz, by incorporating frequency range of the antenna resonates for single wideband with an impedance bandwidth of 23%. The enhancement of impedance bandwidth and gain does not affect the nature of broadside radiation characteristics. This thesis describes the design, operation, and realization of the beamforming such as Sidelobe level (SLL) control and null forming array antenna are examined with the prototype. An antenna radiation pattern beam maximum can be simultaneously placed towards the intended user or Signal of interest (SOl), and, ideally nulls can be positioned towards directions of interfering signals or signals not of interest (SNOIs). Finally, we focused on the adaptive digitally algorithms in compact antenna that faces with mutual coupling. The variable step-size normalized lease mean square (VS-NLMS) algorithm is implemented in beamforming. This algorithm utilizes continuous adaptation. The weights are attuned that the final weight vector to the most satisfied result. The gradient vector can be achieved by iterative beamforming algorithm from the available data. This algorithm is compared with LMS, NLMS, VSS-NLMS algorithms, it is determined that the VSS-NLMS algorithm is better performance to other algorithms. Finally, we introduced novel adaptive IP-NNLMS beamformer. This beamformer reaches to faster convergence and lower error floor than the previous adaptive beamformers even at low SNRs in presence of mutual coupling. The experimental results verified the simulation results that the proposed technique has better performance than other algorithms in various situations.
Show less - Date Issued
- 2016
- PURL
- http://purl.flvc.org/fau/fd/FA00004789, http://purl.flvc.org/fau/fd/FA00004789
- Subject Headings
- Global system for mobile communications., Long-Term Evolution (Telecommunications), Wireless communication systems., Antennas (Electronics), Antenna arrays., Array processors., Time-domain analysis.
- Format
- Document (PDF)
