Abstract
Abstract : A study is made of the amplitude fading of 35 microsecond HF pulses transmitted via the iono sphere over a 1,566-km path between Atlanta, Ga., and Ipswich, Mass. The distribution functions for about half of the records taken fit the family of distributions for a sine wave in Gaussian noise, with most of these best fitting the curve for pure noise (the Rayleigh distribution). Some examples of two sine waves with random phase are observed. It is concluded that most of the re maining curves which do not fit these distribu tions correspond to samples of nonstationary functions. The median fading time for one-hop paths is of the order of 20 seconds, and many ex amples occur with considerably longer fading times. Multiple-hop paths give fading times of a very few seconds. Space correlation distances are also considerably greater than expected, averag ing around 40 wavelengths, which corresponds to a mean angular deviation of the order of two tenths of a degree. Many crosscorrelation functions show peaks displaced in time from the origin, re flecting the effect of ionospheric winds. (Author)
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