March 1992 | NTIA Technical Report TR-92-284
Lewis E. Vogler; James A. Hoffmeyer
Abstract: This is the third in a series of reports which describe a new and unique approach for modeling either narrowband or wideband high frequency (HF) channels. Although narrowband models of the HF channel have existed for many years, they are applicable to only a limited set of actual narrowband propagation conditions. The need for an HF channel model that is valid for both narrow and wide bandwidths over a more extensive range of propagation conditions motivated the research documented in this series of reports. An explicit expression for the channel transfer function incorporating a random time-varying generator is derived and its relation to the impulse response and scattering function is discussed. Comparisons with measured data indicate the process is best modeled as a sequence of random variables with an exponential autocorrelation function; this leads to a scattering function having a Lorentzian shape. A brief discussion of a Gaussian random variable generator is also included. Comparisons of scattering functions from the model and from measurements on a near-vertical incidence auroral path for a wide range of spread-F conditions are shown.
Keywords: HF propagation; HF channel models; channel transfer function; scattering functions; spread spectrum communications; wideband HF
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