A new wideband high frequency channel simulation system

Modeling of RF signals passing through the near-ground trace with terrain relief reflections and troposphere scattering

“…In [10,11], quadrature components of equivalent impulse response characteristic h e (τ) of the radio channel with independent scatters are described by a zeromean white Gaussian noise with a dispersion that changes due to duration of impulse response. Let us consider a discrete representation.…”

“…), the impulse response realizations are formed as a sum of delayed delta pulses a(t-τ i )δ(t-τ i ) with random values of a(t-τ i ) and τ i [10]. For closed near-ground traces with RF wave scattering by small-scale irregularities or a forest edge, the impulse response is described by energy delay profile Е(τ), that results from averaging squared impulse responses for the specific nearground propagation trace [10,11]. As it demonstrated in many papers, the energy delay profile is defined by propagation environment properties, receiving equipment performance and a relative antenna orientation of an emitting source and areceiving unit.…”

“…That is why, the task of achieving realizations of the propagation traces impulse response using the energy delay profile taken from publications is a subject of interest. There are some papers where the energy delay profile is used for modeling signal depression in an ionosphere radio channel [11]. However, there are no approaches developed to form impulse response realizations for near-ground traces under the conditions of frequency-selective depressions.…”

HF propagation in a wideband ionospheric fluctuating reflection channel: Physically based software simulator of the channel

“…This together comprises a very complicated problem for which a comprehensive solution should be given for a variety of realistic models of the ionosphere and geometry of propagation. This explains why different empirical models have been developed [Watterson, 1981;Vogler and Hoffmeyer, 1993;Mastrangelo et al, 1997;Sudworth, 1999; see also Proakis, 1983], which are widely employed [Angling et al, 1998;Messer, 1999;Nieto and Ely, 1999] to characterize the HF fluctuating channel of propagation. By contrast to the empirical approach, we present here a rigorous treatment of the HF propagation in a 3-D inhomogeneous medium disturbed by fluctuations of the electron density of the ionosphere.…”

“…[39] The scattering function of a pulsed signal is introduced [Proakis, 1983;Vogler and Hoffmeyer, 1993;Mastrangelo et al, 1997;Gherm et al, 2001a] as the appropriate Fourier transform of the autocorrelation function of the random channel impulse response on the difference slow time variable. Utilizing (30), the autocorrelation function of a pulsed signal on slow time T can be written as follows:…”