Thesis (M.S.)--Ohio University, August, 1998. / Title from PDF t.p.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Many military communications systems utilize frequency-hopped spread spectrum waveforms to protect against jamming and enemy detection. These waveforms may be subjected not only to intentional jamming but may also be unintentionally jammed by other communications signals. While some systems can overcome inband interference with more signal power, covert systems may be limited to small amounts of transmitted power. The objective of this thesis was to investigate a method for resolving a frequency-hopped signal embedded in interference waveforms. With exponential averaging in the frequency domain, the spectra of the interfering signals can be estimated as long as they are present over a period longer than that of the frequency-hopped signal. Certain FFT sizes and weights are more beneficial to achieving this estimate than others. The interference estimate can be used to extract the desired frequency-hopped signal through spectral division of the received signal with the estimate. This technique is designated as noise-normalization. Simulations in MATLAB demonstrate the use of the technique and show how the desired signal can be resolved.

Roy A. Paananen. / "September 22, 1952." "Based on a thesis presented for the degree of Electrical Engineer, Massachusetts Institute of Technology, 1952." / Bibliography: p. 84-85. / Army Signal Corps Contract DA36-039 sc-100, Project 8-102B-0. Dept. of the Army Project 3-99-10-022.

[by] E.R. Kretzmer. / "This report is identical with a thesis of the same title submitted by the author in partial fulfillment of the requirements for the degree of Doctor of Science in Electrical Engineering at the Massachusetts Institute of Technology." / Bibliography: p. 238-239. / Army Signal Corps Contract No. W-36-039 sc-32037. Dept. of the Army Project No. 3-99-10-022.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Computer Science, 2009. / Includes bibliographical references.

Thesis (Ph. D.)--Ohio University, June, 1990. / Title from PDF t.p.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): R. Clark Robertson. Includes bibliographical references (p. 37-38). Also available online.

Power line carrier (PLC) is one of the communication and load control (C&LC) techniques employed in direct load control. A PLC is, within itself, a communication system. It utilizes power transmission line as a medium of transmitting control functions, and relaying. High frequencies, in the order of 30 to 300 kHz, are used. Power line carrier systems are, at present, the most attractive C&LC systems. Recently, dispersed generation - photovoltaics, wind energy, small scale hydro - is introduced to power systems. The introduction of small scale dispersed generation sources degrades the performance of PLC systems by injecting dc-ac inverter related harmonics into the distribution lines. These harmonics interfere with PLC signals. Thus load control functions assigned to PLC systems are affected. It is the purpose of this research to study how a PLC signal propagates through the transmission line and how it is affected by the harmonic interference. An experiment is conducted using a distribution network provided by the Jet Propulsion Laboratory discussions, and conclusions are presented. / M.S.

Approved for public release, distribution is unlimited / The performance of coherent and noncoherent RAKE receivers over a fading channel in the presence of pulse-noise interference and additive white Gaussian noise is analyzed. Coherent RAKE receivers require a pilot tone for coherent demodulation. Using a first order phase-lock-loop to recover a pilot tone with additive white Gaussian noise causes phase distortions at the phase-lock-loop output, which produce an irreducible phase noise error floor for soft decision Viterbi decoding. Both coherent and noncoherent RAKE receivers optimized for additive white Gaussian noise perform poorly when pulse-noise interference is present. When soft decision convolutional coding is considered, the performance degrades as the duty cycle of the pulse-noise interference signal decreases. The reverse is true for hard decision Viterbi decoding, since fewer bits experience interference and bit errors with high noise variance cannot dominate the decision statistics. Soft decision RAKE receiver optimized for pulse-noise interference and additive white Gaussian noise performed the best for both the coherent and noncoherent RAKE receivers. This receiver scales the received signal by the inverse of the variance on a bit-by-bit basis to minimize the effect of pulse-noise interference. The efficacy is demonstrated by analytical results, which reveal that this receiver reduces the probability of bit error down to the irreducible phase noise error floor when pulse-noise interference is present. This demonstrates how important it is to design the receiver for the intended operational environment. / Civilian, Department of Defense