Analysis of Non-Linear Omega Receivers

Benjamin Peterson, Keith Gross and Ellen Shirvell

Abstract:	A summary of ongoing research analyzing the VLF noise environment and various structures of non-linear Omega receivers is presented. First the noise amplitude is seen to have a probability density function that can be modeled as Gaussian for small amplitudes and as decreasing proportionally to (amplitude)-2.2 for large amplitudes. This model of probability density function suggests a maximum likelihood non-linearity that is linear for small amplitudes and of the form f(x) - l/x for large amplitudes. Analysis of the behavior of two approximations of this non-linearity (hole punch and clipper) is presented. Issues addressed include performance relative to a linear receiver as a function of structure, threshold for either non-linearity, bandwidth prior to non-linearity and signal level. The study included both synthesized signals added to actual noise and off-the-air signals. Improvements of 7-14 dB relative a linear receiver were observed. Finally, it is observed that the presence of a strong local Omega station within the receiver passband results in virtually no improvement relative to a linear receiver.
Published in:	Proceedings of the 1990 National Technical Meeting of The Institute of Navigation January 23 - 25, 1990 Princess Resort Hotel San Diego, CA
Pages:	127 - 134
Cite this article:	Peterson, Benjamin, Gross, Keith, Shirvell, Ellen, "Analysis of Non-Linear Omega Receivers," Proceedings of the 1990 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1990, pp. 127-134.
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