Detection and estimation of frequency hopping signals using wavelet transforms

This thesis investigates the use of wavelet transforms in the detection and estimation of spread spectrum frequency hopping signals. The technique developed in this work makes only two basic assumptions of a minimum hopping time and a minimum frequency hopping differential. The approach is based on the phase information of the temporal correlation function and the resulting discrete wavelet transform is used to estimate the hopping time of frequency hopping signals. Results show the proposed scheme is robust to additive white noise for SNR levels of 3 dB and above.http://archive.org/details/detectionndestim1094531944NANAU.S. Marine Corps (U.S.M.C.) author.Approved for public release; distribution is unlimited

Processing of Second Order Statistics via Wavelet Transforms

The views expressed in this report are those of the author and do not reflect the offical policy or position of the Department of Defense or the United States Government.Research was conducted to evaluate the feasibility of wavelet transforming second order statistics. To identify the modulation type and to extract signal modulation parameters of frequency hopped signals wavelet functions are applied to the two-dimensional instantaneous correlation function. Parameters of interest are switching times and hop frequencies. The characteristics of the wavelet transform of the correlation function is derived. The wavelet transform is applied along the delay and the time axes. Processing along the delay axis allows the identification of frequency hopped signals and estimation of frequencies and switching times. Processing along the time axis allows detection of the transition times of frequency and time hopped signals.Prepared for: Space and Naval Warfare Systems CommandMIPR 97245TApproved for public release; distribution is unlimited

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Perimortem cesarean delivery in a pregnant patient with goiter, preeclampsia, and morbid obesity

Cardiopulmonary arrest during pregnancy is a devastating event necessitating rapid intervention from experienced practitioners to reduce the incidence and severity of adverse maternal and fetal outcomes. Perimortem cesarean delivery is rarely performed within the recommended time frame to meet these goals. We describe a case of a successful perimortem cesarean delivery after the 4-minute rule in a morbidly obese parturient with goiter and preeclampsia

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