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Varactors, crystals, and their use in voltage controlled oscillators
Title
Varactors, crystals, and their use in voltage controlled oscillators.
Creator
Fenton, Eliot Darrel., Florida Atlantic University, Ungvichian, Vichate
Abstract/Description
This thesis investigates the characteristics of varactors and crystals that affect Q and therefore the frequency stability of a voltage controlled oscillator (vco) when employed in a one MHz to three hundred MHz frequency synthesizer. A low noise VHF crystal oscillator, a low noise common base UHF oscillator, and a low noise test set-up are described, built, and tested.
Date Issued
1991
PURL
http://purl.flvc.org/fcla/dt/14676
Subject Headings
Oscillators, Electric, Oscillators, Crystal
Format
Document (PDF)
Numerical Investigation of Finite Kuramoto model with time dependent coupling strength
Title
Numerical Investigation of Finite Kuramoto model with time dependent coupling strength.
Creator
Khatiwada, Dharma Raj, Wille, Luc T., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
Abstract/Description
Synchronization of an ensemble of oscillators is a phenomenon present in systems of different fields, ranging from social and physical to biological and technological systems. The most successful approach to describe how synchrony emerges in these systems is given by the Kuramoto model. This model as it stands, however, assumes oscillators of fixed natural frequencies and a homogeneous all-to-all coupling strength. The Kuramoto model has been analytically discussed to address the...
Show moreSynchronization of an ensemble of oscillators is a phenomenon present in systems of different fields, ranging from social and physical to biological and technological systems. The most successful approach to describe how synchrony emerges in these systems is given by the Kuramoto model. This model as it stands, however, assumes oscillators of fixed natural frequencies and a homogeneous all-to-all coupling strength. The Kuramoto model has been analytically discussed to address the synchronization phenomena of coupled oscillators in the thermodynamic limit (N --> ∞). However, there needs to be a modi cation to address the inevitable in uence of external fields on the pattern of various real life synchronization phenomena which, in general; involves a finite number of oscillators. This research introduces a time dependent coupling strength K(t) which is from the modulation of external elds in the form of, for example, a periodic impulse, in the nite oscillators assembly. A sinusoidal function with some arbitrary values of amplitude and frequency is added to the fixed coupling strength as a perturbation of external elds. Temporal evolution of order parameter r(t) and phase θ(t), both of which measure the degree of synchronization of an assembly of oscillators simultaneously, are compared between uniform and time dependent cases. Graphical comparison are made using a 2 oscillator system, a building block of any finite oscillators case. Also, similar comparisons are performed for a system of 32 oscillators which are chosen randomly as a representative of a nite number of oscillators (2 < N < ∞). A temporal variation of the relative phase angle θ(t) = θ2(t) - θ1(t) in 2 and 32 oscillators systems using uniform and time dependent cases is also a part of this research. This work also introduces a time-dependent coupling strength in the form of a step function. The main objective of using such a function is to keep the synchronized behavior of the oscillators persistently. This behavior can be achieved with the perception that occasional boosting with higher coupling strength K(t) should be enough to sustain synchronous behavior of oscillators which, in general, are tuned with lower K(t).
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Date Issued
2018
PURL
http://purl.flvc.org/fau/fd/FA00013120
Subject Headings
Synchronization, Oscillations, Nonlinear oscillators--Mathematical models, Oscillator strengths, Frequency of oscillating systems
Format
Document (PDF)
PRECISION TC SYSTEM FOR MEASURING ACTIVITY DIPS OF QUARTZ CRYSTALS
Title
PRECISION TC SYSTEM FOR MEASURING ACTIVITY DIPS OF QUARTZ CRYSTALS.
Creator
Peterson, Vance Howard, Florida Atlantic University, Graham, Peter, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
There is an increasing market demand for quartz crystals which exhibit minimal activity dip or frequency anomalies over a predefined temperature range. Characterization of the frequency vs temperature (f-T) activity dip profiles of these tight tolerance crystals is best carried out using a system which has been expressly designed for such a purpose. Frequency measurement accuracy and reliable temperature control must be established in the system, along with its being compatible with a...
Show moreThere is an increasing market demand for quartz crystals which exhibit minimal activity dip or frequency anomalies over a predefined temperature range. Characterization of the frequency vs temperature (f-T) activity dip profiles of these tight tolerance crystals is best carried out using a system which has been expressly designed for such a purpose. Frequency measurement accuracy and reliable temperature control must be established in the system, along with its being compatible with a computer controlled production or engineering enviornment. This thesis will present design and implementation details for a system with the aformentioned objective of enabling the generation of accurate crystal activity dip data. The system will provide the user with up-to-date facilities for meeting the temperature testing requirements of tight tolerance crystals.
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Date Issued
1986
PURL
http://purl.flvc.org/fcla/dt/14343
Subject Headings
Quartz crystals, Oscillators, Crystal
Format
Document (PDF)
DESIGN OF HIGH FREQUENCY OSCILLATORS: NOISE CHARACTERIZATION, DESIGN THEORY, AND MEASUREMENTS
Title
THE DESIGN OF HIGH FREQUENCY OSCILLATORS: NOISE CHARACTERIZATION, DESIGN THEORY, AND MEASUREMENTS.
Creator
VICTOR, ALAN MICHAEL., Florida Atlantic University, Gazourian, Martin G., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
A design theory for high frequency oscillators is presented. Emphasis is placed on oscillator design techniques which are applicable to the electrical tuning of LC and transmission line resonators. Attention is paid to design approaches which yield an oscillator with high spectral purity and a large signal to noise ratio. Theory and measurements demonstrate for the oscillator configurations investigated the a small L/C ratio is desirable for improved oscillator signal to noise ratio....
Show moreA design theory for high frequency oscillators is presented. Emphasis is placed on oscillator design techniques which are applicable to the electrical tuning of LC and transmission line resonators. Attention is paid to design approaches which yield an oscillator with high spectral purity and a large signal to noise ratio. Theory and measurements demonstrate for the oscillator configurations investigated the a small L/C ratio is desirable for improved oscillator signal to noise ratio. Equations are developed which define the noise figure the oscillator due to the additive noise of the active device. This analysis demonstrates the need for a high device starting transconductance which should be subsequently reduced during oscillation to minimize the device noise contribution. A relationship is developed between the receiver dynamic range and the oscillator signal to the noise ratio. Oscillator designs in the region 20 Mhz - 200 Mhz verify the analysis. A unified approach to large signal oscillator design is investigated and relationships to oscillator signal to noise ratio using the previously developed theory are noted
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Date Issued
1980
PURL
http://purl.flvc.org/fcla/dt/14043
Subject Headings
Oscillators, Audio-frequency
Format
Document (PDF)
An investigation of near-bottom flow patterns along and across Hawk Channel, Florida Keys
Title
An investigation of near-bottom flow patterns along and across Hawk Channel, Florida Keys.
Creator
Pitts, Patrick A., Harbor Branch Oceanographic Institute
Date Issued
1994
PURL
http://purl.flvc.org/FCLA/DT/3172796
Subject Headings
Ocean currents, Tides, Tidal currents, Hydrodynamics, Oscillations
Format
Document (PDF)
Theory of and a novel approach to high-stability frequency control circuits
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.
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Date Issued
2001
PURL
http://purl.flvc.org/fcla/dt/12819
Subject Headings
Frequency synthesizers, Automatic frequency control, Oscillators, Crystal
Format
Document (PDF)
Acceleration charge sensitivity in AT-quartz resonators
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.
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Date Issued
1995
PURL
http://purl.flvc.org/fcla/dt/15126
Subject Headings
Quartz crystals, Piezoelectricity, Oscillators, Crystal, Resonators, Acceleration (Mechanics)
Format
Document (PDF)
Simulations and feedback control of nonlinear coupled electromechanical oscillators for energy conversion applications
Title
Simulations and feedback control of nonlinear coupled electromechanical oscillators for energy conversion applications.
Creator
Psarrou, Dimitrios., Dhanak, Manhar R., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
This thesis discusses the coupling of a mechanical and electrical oscillator, an arrangement that is often encountered in mechatronics actuators and sensors. The dynamics of this coupled system is mathematically modeled and a low pass equivalent model is presented. Numerical simulations are then performed, for various input signals to characterize the nonlinear relationship between the electrical current and the displacement of the mass. Lastly a framework is proposed to estimate the mass...
Show moreThis thesis discusses the coupling of a mechanical and electrical oscillator, an arrangement that is often encountered in mechatronics actuators and sensors. The dynamics of this coupled system is mathematically modeled and a low pass equivalent model is presented. Numerical simulations are then performed, for various input signals to characterize the nonlinear relationship between the electrical current and the displacement of the mass. Lastly a framework is proposed to estimate the mass position without the use of a position sensor, enabling the sensorless control of the coupled system and additionally providing the ability for the system to act as an actuator or a sensor. This is of value for health monitoring, diagnostics and prognostics, actuation and power transfer of a number of interconnected machines that have more than one electrical system, driving corresponding mechanical subsystems while being driven by the same voltage source and at the same time being spectrally separated and independent.
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Date Issued
2011
PURL
http://purl.flvc.org/FAU/3320109
Subject Headings
Renewable energy sources, Mechatronics, Nonlinear theories, Oscillators, System analysis
Format
Document (PDF)
The influence of connectivity on the global dynamics of nonlinear oscillator ensembles
Title
The influence of connectivity on the global dynamics of nonlinear oscillator ensembles.
Creator
Rogers, Jeffrey L., Florida Atlantic University, Wille, Luc T.
Abstract/Description
In this thesis we have studied the global dynamics which spontaneously emerge in ensembles of interacting disparate nonlinear oscillators. Collective phenomena exhibited in these systems include synchronization, quasiperiodicity, chaos, and death. Exact analytical solutions are presented for two and three coupled oscillators with phase and amplitude variations. A phenomenon analogous to a phase-transition is found as a function of interaction-range in a one-dimensional lattice: for coupling...
Show moreIn this thesis we have studied the global dynamics which spontaneously emerge in ensembles of interacting disparate nonlinear oscillators. Collective phenomena exhibited in these systems include synchronization, quasiperiodicity, chaos, and death. Exact analytical solutions are presented for two and three coupled oscillators with phase and amplitude variations. A phenomenon analogous to a phase-transition is found as a function of interaction-range in a one-dimensional lattice: for coupling exponents larger than some critical value, alpha c, synchronization is shown to be impossible. Massively parallel computer simulations in conjunction with finite-size scaling were used to extrapolate to the infinite-size limit.
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Date Issued
1994
PURL
http://purl.flvc.org/fcla/dt/15031
Subject Headings
Nonlinear oscillators, Coupled mode theory, Physics--Data processing, Parallel processing (Electronic computers)
Format
Document (PDF)