Signal level statistics and case studies for an over‐the‐horizon mid‐Atlantic coastal link operating at C‐band

Abstract

Abstract. We examine the results of 1 year of near-continuous measurements for a 128-km over-the-horizon C-band coastal propagation link. The link extends between Dam Neck, Virginia (16 km south of Virginia Beach), and Wallops Island, Virginia (approximately 150 km southeast of Washington, D.C.). The objectives of this effort are to explore the different mechanisms of propagation through an analysis of several case studies and to assess the statistical connectivity over the 1-year period. Case studies involving the linking of environmental information and measured signal levels are analyzed. Propagation factor levels due to evaporation ducts, surface ducts, and scattering from irregularities of the refractive index in the common volume are determined. Cumulative distributions of the measured propagation factor for the annual, fall-winter, and spring-summer periods are presented. Conditional and absolute distributions of propagation factor time durations are also presented and analyzed. It is demonstrated that during the spring-summer period, received signal levels were consistent with ducting and not with troposcatter. The fall-winter levels may be due to troposcatter from irregularities of the refractive index. The months giving the smallest and largest propagation factors were January and June, respectively. IntroductionThere is a continuing need to better understand the propagation conditions associated with ship-to-ship and ship-to-shore communications and radar opera-

Mesoscale Modeling of Boundary Layer Refractivity and Atmospheric Ducting

“…Rapid transitions in synoptic weather regimes are well documented over the Wallops Island region during the spring season (Babin 1996;Goldhirsh et al 1994;Goldhirsh and Musiani 1999). The present study begins on 28 April with a deep trough over the eastern United States that slowly moved out of the area early on 30 April.…”

Oceanic propagation measurements for beyond line-of-sight links at Q band

“…Troposcatter occurs when transmitted energy is reflected off of scatterers in the region of the atmosphere defined by the intersection of the transmitting and receiving beams. For the case in which scatterers uniformly occupy the common volume and spatially radiate with random phases, Goldhirsh [4] presents the following expression for the propagation factor (in dB) associated with troposcatter, PF tropo : (1) where P r is the received power due to troposcatter, P fs is the free-space received level, d t and d r are the distances from the transmitter and receiver to the common volume, respectively, η is the reflectivity (scattering cross section per unit volume per meter), and V denotes the common volume.…”