Abstract

The arrival time of an electromagnetic or optical pulse as observed by a fixed observer can be defined by the first temporal moment or the “time centroid” of the pulse. After propagating through a random medium, this pulse arrival time becomes a random variable and will fluctuate about some mean value. It is then of interest to investigate the statistical properties of this quantity, which as shown in this paper can be done by using the multifrequency mutual coherence functions for the propagation channel. In particular, the statistical moments for the pulse arrival time are derived in the limit of very strong scintillations such that the fluctuations are in the fully saturated regime. Under this extreme limit, we find that the mean arrival time can exceed the free space time delay by an appreciable value. At the same time, our calculations indicate that fluctuations about the mean arrival time are very small when compared with the excess time delay. This suggests that the excess delay time is caused mainly by pulse spreading and not by pulse wandering.

© 1980 Optical Society of America

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References

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Equations (32)

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