Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 12 of 12
Full-Text Articles in Engineering
Doppler Aliasing Reduction In Wide-Angle Synthetic Aperture Radar Using Phase Modulated Random Stepped-Frequency Waveforms, Andrew W. Hyatt
Doppler Aliasing Reduction In Wide-Angle Synthetic Aperture Radar Using Phase Modulated Random Stepped-Frequency Waveforms, Andrew W. Hyatt
Theses and Dissertations
This research effort examines the theory, application and results of side-looking airborne radar operation in hot clutter. Hot clutter is an electronic counter-measure used to degrade the performance of airborne radar. Hot clutter occurs by illuminating the ground with an airborne jammer at some velocity, azimuth, elevation, and range from the airborne radar. When the received RCS scattered hot clutter waveform is perfectly coherent with the radar waveform, the radar believes the returns created by the hot clutter jammer resulted from the transmitting radar. Hot clutter degrades radar performance at locations in azimuth and Doppler. The effect of hot clutter …
Doppler Aliasing Reduction In Wide-Angle Synthetic Aperture Radar Using A Linear Frequency Modulated Random Stepped-Frequency Waveform, Jason R. Mcmahon
Doppler Aliasing Reduction In Wide-Angle Synthetic Aperture Radar Using A Linear Frequency Modulated Random Stepped-Frequency Waveform, Jason R. Mcmahon
Theses and Dissertations
This research examines the theory, application, and results of using Random Stepped-Frequency (RSF) waveforms to mitigate Doppler aliasing in a wide-angle Synthetic Aperture Radar (SAR) imaging scenario. Severe Doppler aliasing typically occurs in this scenario since range extent requirements force the pulse repetition frequency to a value violating the lower bound for Doppler aliasing. Building on previous research, this work expands upon RSF waveform analysis using a Linear Frequency Modulated RSF (LFM-RSF) waveform. The RSF waveform suppresses Doppler aliasing by positioning nulls at the aliased scatterer location. Applying LFM with RSF processing theoretically provides greater frequency coverage and aliased scatterer …
Application Of Autoregressive Moving Average Linear Prediction Filters To The Characterization Of Solar Wind-Magnetosphere Coupling, Carter N. Borst
Application Of Autoregressive Moving Average Linear Prediction Filters To The Characterization Of Solar Wind-Magnetosphere Coupling, Carter N. Borst
Theses and Dissertations
Linear prediction filtering techniques have been used in studying the coupling processes between the solar wind and magnetosphere. The magnetosphere is a complex, dynamic system with at least two independent coupling methods for energy input, driven and unloading. Linear models were built and tested on the Bargatze data set, consisting of over 70 days of geomagnetic indices and solar wind data ordered in 34 intervals of increasing geomagnetic activity. Linear filtering techniques employing single-and multiple-input, autoregressive models predicted values of the magnetic index AL from solar wind data. The impulse response curves of the AL-coupling function groups showed amplitude peaks …
Application Of The Wavelet Transform To Biomedical Signals, Karl O. Hauck
Application Of The Wavelet Transform To Biomedical Signals, Karl O. Hauck
Theses
The basic concepts and fundamentals of the wavelet signal representation were examined. The orthonormal wavelet was selected for this project after being compared to various types of wavelets. The orthonormal wavelet was chosen due to the equal time and frequency resolution exhibited in the wavelet coefficients. Programs were written in Matlab to implement the orthonormal wavelet in developing wavelet coefficients for a given signal. The programs include the conditions for an orthonormal wavelet in and which produce the wavelet filters g(n) and h(n). The wavelet filters were then incorporated into another program that applied Mallat's multiresolution algorithm for a given …
Digital Signal Processing Capabilities Of The Fujitsu Mb8764, Harold B. Creech
Digital Signal Processing Capabilities Of The Fujitsu Mb8764, Harold B. Creech
Retrospective Theses and Dissertations
The Fujitsu MB8764 digital signal processing chip is designed to operate with a machine cycle of up to 10 MHz. The chip’s ability to perform a 16-by-16 bit multiply and add operation in one machine cycle makes it a good candidate for real time digital signal processing. Unlike the Intel 2920 the Fujitsu MB8764 does not have an onboard analog-to-digital, digital-to-analog converter. Therefore, this paper will be restricted to the operation of this device with digital data input and output. The use of the MB8764 as a digital filter is analyzed. Performance limitations due to finite word length, memory size …
Application Software Of The Future-Filter Design With Gem, Alan D. George
Application Software Of The Future-Filter Design With Gem, Alan D. George
Retrospective Theses and Dissertations
As the use of computer in engineering design as well as other areas increase, it becomes more imperative that the application software used be as simple, convenient, and powerful as possible. The engineer is not interested in the internal workings of the computer or its operating system. It is the design itself that takes precedence. The filter design package developed for this project, known as FILTER, is such an application. With FILTER, coupled with the Digital Research Graphics Environment Manager, the engineer is led through the analog and digital filter design phase on a personal computer with carefully designed interactive …
Effects Of Finite Length Registers On A Modified Directform Realization Of A High Order H(Z) Transfer Function, Angel Vanrell
Effects Of Finite Length Registers On A Modified Directform Realization Of A High Order H(Z) Transfer Function, Angel Vanrell
Retrospective Theses and Dissertations
When a digital process is realized on a general-purpose computer or a special-purpose hardware, errors due to finite register length are introduced. These errors are due primarily to arithmetic roundoff, coefficient quantization, and scaling rules. This paper addresses the effects of finite word length on a direct-form implementation of a high order H (z) transfer function. The development and analysis of a modified direct-form realization suggested by Dr. Fred O. Simons, are carried out via FORTRAN emulation of a fourth-order low-pass Butterworth filter. The results are presented as a parametric tradeoff of signal-to-noise ratio at the filter output versus word …
Finite Impulse Response Filter Implementation Via Windowing Technique, Thomas J. Horrigan
Finite Impulse Response Filter Implementation Via Windowing Technique, Thomas J. Horrigan
Retrospective Theses and Dissertations
This research report is devoted to an investigation of finite impulse response (FIR) filters and their implementation via windowing techniques. Analysis is restricted to those FIR filters that possess both a nonrecursive structure and a linear phase response. Initially an informative yet concise overview of FIR filters is presented. Some knowledge of "discrete – time" systems is assumed. Next, the concepts associated with FIR filter implementation through the utilization of window functions is developed. Analysis is performed in both the time and frequency domains. Results obtained define optimal window function criteria. The last design technique is devoted to computer aided …
Digital Hearing Aids, Somsak Deawsurintr
Digital Hearing Aids, Somsak Deawsurintr
Retrospective Theses and Dissertations
This paper describes the design of a hearing aid using digital techniques. The Amplitude Compression Amplifier and Digital Filter are discussed. General review of different filter types are presented as background for the design of Digital Filters. The design procedure for Digital Filters and the software program for the Intel-2920 signal processor are created. Finally, the program is tested by simulation via the 2920-Simulator.
Computer Simulation Of Cross Correlators For Correlated Inputs, Linda J. Coulter
Computer Simulation Of Cross Correlators For Correlated Inputs, Linda J. Coulter
Retrospective Theses and Dissertations
Cross correlator systems, analog and clipped input channels, with correlated random narrow band Gaussian noise as inputs are computer simulated. The performance of each system is evaluated on the basis of the output signal-to-noise ratio. The output SNR of each system is compared with theoretical asymptotic approximations computed as a function of the SNR of the input channels. The output of the simulation compares within 3 dB of the asymptotic approximations for the analog correlator for all values of the correlation coefficient tested and for the systems with clipped input channels with uncorrelated inputs. For the systems with clipped input …
Digital Filtering With The Iapx 86/20, Robert E. Canright
Digital Filtering With The Iapx 86/20, Robert E. Canright
Retrospective Theses and Dissertations
The iAPX 86/20 (8086 with the 8087 numeric coprocessor) is considered for digital filtering. The advantage in using the iAPX 86/20 lies in the 80-bit width of the 8087 floating-point arithmetic-registers. With such large arithmetic registers, the effects of coefficient roundoff and arithmetic roundoff errors on the filter output are reduced. The price paid for the improved numerical performance is the increased time spent by the system moving data to and from memory. The method of Knowles and Olcayto for measuring the effect of coefficient roundoff is studies in detail. This method is applied to an example filter in order …
A Real Time Microprocessor Based Digital Filter Implementation, Mark H. Shaver
A Real Time Microprocessor Based Digital Filter Implementation, Mark H. Shaver
Retrospective Theses and Dissertations
A major break-through in the real-time digital simulation of dynamic models has occurred with the introduction of the Intel 2920 digital signal processing chip. The problems and potentials for this new device are demonstrated by implementing an elliptic function digital low pass filter via the bilinear z-transform approach. The software implementation is presented. Debugging and software verification are accomplished via manufacturer's simulation software tools. The hardware performance is verified in the laboratory. The results of these efforts point to much promise for wide scale applications, however, problems associated with performance indicate early version chip problems.