Detailed Data Analysis of Echo I, Echo II and Moon Reflected Signals. Volume 2. Autocorrelation Functions of Echo II Reflected Signals

摘要

The report deals with the short-term autocorrelation function of Echo I-reflected signals. The sample lengths were 30 seconds; maximum time delays were approximately ten per cent of sample length. The autocorrelation function is discussed, and the adaptation of its computation to digital techniques is presented. Two methods for linearizing the data are given. An expression for the specular-to-spattered power ratio is derived, and the inverse transform of the autocorrelation function is discussed. The surface roughness of the reflector, the discrete fading rates, and fading frequencies are considered in detail. More than 50 autocorrelation curves are shown. These autocorrelation functions were obtained from pulsed and from cw signals, at sampling rates of 29, 50, and 100 per second during different revolutions, with the satellite in various path geometries, and with the data linearized and not linearized prior to computing the autocorrelation function. In applicable cases the specular-to-scattered power ratio was computed. Qualitative evaluation of the Fourier transform of the ACF, i.e., by the power spectrum, is also presented. (Author)