The authors describe the application of the singular value decomposition Prony (SVDP) algorithm to the analysis of the time-variant structure of a microwave line-of-sight multipath channel. The algorithm deduces the multipath ray delays and associated amplitudes from measurements made in the frequency domain. The capability of this algorithm to resolve closely spaced rays is demonstrated by analyzing both computer simulated data and field measurements. The authors present experimental results of the time-variant structure of the transmittance H(jw,t) and include the evolution in time of the amplitude, group delay, and the constituting rays thus giving direct insight into the underlying multipath mechanism of line-of-sight microwave links.>

This study is concerned with using modern spectral analysis techniques to derive estimates of multipath ray parameters (delays and amplitudes) from measurements of selective fading over a wide band at microwave frequencies. The applicability of the general category of autoregressive methods is addressed, and the specific method adopted, the Prony algorithm, is described. An illustrative example in which this is applied to a typical field measurement is followed by an investigation into the capabilities and limitations of the algorithm. A statistical analysis of the method has been carried out using a database of laboratory measurements. The Prony algorithm's ability to resolve delays to better than half the Fourier limit is shown, and its tendency to yield biased estimates is studied.>

A survey is presented of techniques for measuring selective fading on line-of-sight (LOS) microwave links, particularly over a wide band. Classical pulse methods, including pulse compression, as well as the much used frequency-sweep approach are covered. Methods utilizing both frequency-hopping and direct-sequence spread-spectrum transmissions are also discussed. An analysis of this latter method (used by the US National Bureau of Standards and by the authors) is included and a relationship is established between the true channel transmittance and that estimated by this approach. The advantages and disadvantages of the various schemes are outlined with the aim of assisting an experimenter in the choice of technique in a given experimental context.>