Matching Items (5)
Description
This dissertation proposes a miniature FIR filter that works at microwave frequencies, whose filter response can ideally be digitally programmed. Such a frequency agile device can find applications in cellular communications and wireless networking. The basic concept of the FIR filter utilizes a low loss acoustic waveguide of appropriate geometry that acts as a traveling wave tapped-delay line. The input RF signal is applied by an array of capacitive transducers at various locations on the acoustic waveguide at one end that excites waves of a propagating acoustic mode with varying spatial delays and amplitudes which interfere as they propagate. The output RF signal is picked up at the other end of the waveguide by another array of capacitive transducers. Tuning of the FIR filter coefficients is realized by controlling the DC voltage profile applied to the individual transducers which essentially shapes the overall filter response. Equivalent circuit modeling of the capacitive transducer, acoustic waveguide and transducer-line coupling is presented in this dissertation. A theoretical model for the filter is developed from a general theory of an array of transducers exciting a waveguide and is used to obtain a set of filter design equations. A MATLAB based circuit simulator is developed to simulate the filter responses. Design parameters and simulation results obtained for an example waveguide structure are presented and compared to the values estimated by the theoretical model. A waveguide structure utilizing the Rayleigh-like mode of a ridge is then introduced. A semi-analytical method to obtain propagating elastic modes of such a ridge waveguide etched in an anisotropic crystal is presented. Microfabrication of a filter based on ridges etched in single crystal Silicon is discussed along with details of the challenges faced. Finally, future work and a few alternative designs are presented that can have a better chance of success. Analysis and modeling work to this point has given a good understanding of the working principles, performance tradeoffs and fabrication pitfalls of the proposed device. With the appropriate acoustic waveguide structure, the proposed device could make it possible to realize miniature programmable FIR filters in the GHz range.
ContributorsGalinde, Ameya (Author) / Abbaspour-Tamijani, Abbas (Thesis advisor) / Chae, Junseok (Committee member) / Pan, George (Committee member) / Phillips, Stephen (Committee member) / Arizona State University (Publisher)
Created2013
Description
Human activity produces ambient noise that potentially alters species’ abilities to communicate with each other—among other impacts. Given that birds are known to be sensitive to structural changes in habitat and highly communicative through sound, it is beneficial to understand how changing acoustic ecologies and ambient noise impact birds’ ability to communicate in their respective environments. In this study, mockingbird calls from an urban, desert, and intermediate study site were recorded and analyzed for differences in acoustic properties. Acoustic properties such as frequency and amplitude differed significantly across sites as it was determined that mockingbirds in urban areas increase both the peak frequency and amplitude of their calls in order to communicate. This study identifies what these changes in acoustic properties mean in relation to the survival and conservation of birds and concludes with recommendations for novel research.
ContributorsReynolds, Bailey Susana (Author) / Pearson, David (Thesis director) / Walters, Molina (Committee member) / School of Sustainability (Contributor) / School of Life Sciences (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This thesis is a proposition for an addition to an engineering project that involves creating a heads up display for a scuba diving mask which displays important safety information. The premise of this thesis includes three different features: distress, distance, and direction. The distress feature is to alert a diver that their “buddy diver” is having an emergency and is requiring attention. Distance and direction are intended to be included on the heads up display, informing the diver of the relative location of their “buddy diver” in case they have lost sight of them. A set of requirements was created to find the most practical solutions. From these requirements and extensive research, three potential methods of underwater communication were found; electromagnetic waves in the radio frequency range, optical waves, and acoustic waves. Of these three methods, acoustic waves were found to be most feasible for the scope of this project. Using modems and transducers, an acoustic signal is able to be sent from one diver to another in order to detect relative location as well as send a message of distress. Ultimately, two possible concepts were designed, with one deemed as most advantageous. This concept engages the use of four transponders that have the ability to transmit and receive high frequencies, minimizes blind spots, and is small enough to not cause discomfort or be obstructive to the divers experience. Due to the nature of this application, the team is able to propose a path of development for a compact communication system between scuba divers.
ContributorsNossaman, Grace (Co-author) / Hocken, Chase (Co-author) / Padilla, Bryan (Co-author) / Richmond, Christ D. (Thesis director) / Baumann, Alicia (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This thesis is a proposition for an addition to an engineering project that involves creating a heads up display for a scuba diving mask which displays important safety information. The premise of this thesis includes three different features: distress, distance, and direction. The distress feature is to alert a diver that their “buddy diver” is having an emergency and is requiring attention. Distance and direction are intended to be included on the heads up display, informing the diver of the relative location of their “buddy diver” in case they have lost sight of them. A set of requirements was created to find the most practical solutions. From these requirements and extensive research, three different methods of underwater communication were found, but only one, acoustics, was feasible for the scope of this project. Using modems and transducers, an acoustic signal is able to be sent from one diver to another in order to detect relative location as well as send a message of distress. Ultimately, two possible concepts were designed, with one deemed as most advantageous. This concept engages the use of four transponders that have the ability to transmit and receive high frequencies, minimizes blind spots, and is small enough to not cause discomfort or be obstructive to the divers experience.
ContributorsHocken, Chase (Co-author) / Nossaman, Grace (Co-author) / Padilla, Bryan (Co-author) / Richmond, Christ D (Thesis director) / Baumann, Alicia (Committee member) / Electrical Engineering Program (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This thesis is a proposition for an addition to an engineering project that involves creating a heads up display for a scuba diving mask which displays important safety information. The premise of this thesis includes three different features: distress, distance, and direction. The distress feature is to alert a diver that their “buddy diver” is having an emergency and is requiring attention. Distance and direction are intended to be included on the heads up display, informing the diver of the relative location of their “buddy diver” in case they have lost sight of them. A set of requirements was created to find the most practical solutions. From these requirements and extensive research, three potential methods of underwater communication were found; electromagnetic waves in the radio frequency range, optical waves, and acoustic waves. Of these three methods, acoustic waves were found to be most feasible for the scope of this project. Using modems and transducers, an acoustic signal is able to be sent from one diver to another in order to detect relative location as well as send a message of distress. Ultimately, two possible concepts were designed, with one deemed as most advantageous. This concept engages the use of four transponders that have the ability to transmit and receive high frequencies, minimizes blind spots, and is small enough to not cause discomfort or be obstructive to the divers experience. Due to the nature of this application, the team is able to propose a path of development for a compact communication system between scuba divers.
ContributorsPadilla, Bryan (Co-author) / Nossaman, Grace (Co-author) / Hocken, Chase (Co-author) / Richmond, Christ D. (Thesis director) / Baumann, Alicia (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05