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The spatial correlation of rainfall over Europe is investigated. A full year of 1 km ?? 1 km composite rain maps, collected by the British NIMROD weather radar network over an area as wide as 1000 km ?? 600 km, is used to calculate the rain rate statistical dependence index ?? for separation distances D up to 1000 km. The average trend of ?? with distance derived from NIMROD rain maps is compared...
Free Space Optical (FSO) links enable high-speed data transfer from Earth Observation satellites or deep space (DS) probes directly to ground stations. The presence on-board of remote sensing instruments with ever increasing accuracy and resolution fuels the need for transmitting huge amounts of data. This contribution investigates the impairments to optical beam propagation due to clouds by exploiting...
This contribution is aimed at presenting the scenario of the expected atmospheric impairments suffered by a radio link operating in the W band, as derived by the present theoretical and experimental knowledge. The contributions to signal fade due to gases, clouds, scintillation and rain (with emphasis also on the impact of the hydrometeor size distribution), as well as the melting layer characteristics...
Radar simulators that are able to accurately reproduce the signal coming from a synthetic environment are powerful instruments for the assessment of the performance of new radar systems. In this work we describe a new airborne meteorological radar simulator that combines the description of the meteorological scenario at mesoscale level with the capability of generating accurate time series of raw...
This contribution investigates the performance of the model currently recommended by ITU-R for the synthesis of rain attenuation time series (recommendation P.1853). The Synthetic Storm Technique (SST) is used to generate reference rain attenuation time series from one year of 1-minute integrated rain rate samples collected by means of a disdrometer located at Kuala Lumpur, Malaysia. First-and second-order...
The assessment of the variability of rainfall characteristics in the equatorial regions is a key problem in estimating adequate fade margin due to rain attenuation in satellite communication systems. Based on one year of disdrometer data that have been collected in Kuala Lumpur, Malaysia, this paper investigates the general characteristics of the raindrop size distribution (DSD) and the dependence...
Satellite communication systems operating above 10 GHz can experience severe rain attenuation; well established countermeasures are site and time diversity. In this paper we exploit experimental data collected in Spino d'Adda to show that the performance of site-diversity systems can be linked to that of time-diversity systems through a precise time-space parameter (the average effective velocity)...
A physically-oriented statistical prediction of sky-noise temperature intercepted by ground Deep-Space antennas has been developed, based on simulations obtained by using a radiative transfer model approaching the electromagnetic propagation in a scattering medium. A model dependent on attenuation, frequency and elevation angle is proposed for describing the atmospheric mean radiative temperature,...
In TLC satellite systems operating in the Ka-band, the dynamic control of the on-board antenna pattern is recognized as an effective countermeasure against the atmospheric attenuations due to rain, water vapour, etc. The on-board available power is better exploited when distributed on the service area by privileging the sub-regions requiring, at a given time, more power to counteract the local attenuation...
In recent years the demand for high data rate satellite links in Earth Observation (EO) missions has increased because of the adoption of instruments with higher resolution. The high data rate systems envisaged require then very large bandwidth and for this reason the use of the Ka band for the Earth Observation Satellites has been planned. In the case of Space Exploration Systems (SES), the continuous...
Propagation Impairments Mitigation Techniques (PIMTs) are necessary for satellite-based systems (typically operating at frequencies above 20 GHz) intended to provide large bandwidth to the end users. This contribution presents the best performing space-time channel model to be used in the design and control of adaptive SatCom systems. First, models able to predict the spatial distribution of the rain...
Numerical Weather Predictions (NWPs) may be used as global meteorological input to several models for the estimation of radiowave atmospheric impairments. This contribution extends the evaluation of the effectiveness of SPET (Spatial P(R) Estimation Technique), a methodology recently proposed to estimate the spatial distribution of point rain rate, PS(R), from cumulative rain precipitation data, namely...
This contribution presents a simplified approach to the planning of the space-segment resources of an advanced SatCom system using ACM (Adaptive Coding and Modulation) with the aim of evaluating the impact of rain fade on space resource planning. Specifically, the MultiEXCELL model is used as a means to include the spatial variability of rainfall, and is applied to the uplink path of the return link...
The objective of this contribution is the review of remote sensing and navigation data in order to provide an overview on meteorological parameters important for propagation modelling up to W band. Such data are also useful to assess the accuracy of the propagation models and analyse propagation impairment mitigation techniques (PIMTs). The review will focus on water vapour and cloud properties that...
The increasing demand of advanced applications to be delivered to end users using SatCom systems requires to shift to higher operating frequencies to guarantee the necessary bandwidth. In this scenario, severe propagation impairments, which are strictly related to the space-time structure of the atmosphere, limit the system performance. This contribution presents an overview on the availability of...
Various measurement campaigns have been carried out at different locations by several institutes to study the weather effects, mainly fog, on Free-space optical (FSO) links. Link distance between the FSO transceiver is different for most of the measurement campaigns depending upon the installation and the weather conditions. Specific attenuation with the unit of dB/km is widely used for the detailed...
Wireless optical links are being increasingly deployed in a variety of indoor and outdoor applications. While it is known that fog and clouds produce the highest attenuation values on optical waves travelling through the Earth's atmosphere, it is shown here that other particulates as rain and snow might have a non-negligible effect, depending on the local climatology and on the quality of service...
Time diversity is an advanced technique that can be employed to mitigate the detrimental effects of the atmosphere - markedly, of precipitation - on wireless telecommunication systems operating above 10 GHz. A new methodology for the simulation of an Earth-space time diversity system and for the evaluation of its performance is presented here. The proposed methodology requires as input a set of rain...
This paper presents the application of the Lowered EXCELL model to discriminate between stratiform and convective precipitation in Kuala Lumpur, Malaysia, which is located in the equatorial region. The model generates two longterm cumulative distribution functions (CDFs) that separately account for the two different types of rain, based on the input rainfall statistics reflecting the local climatology...
The aim of this paper is to provide additional information about the performance of the SC EXCELL model, specifically when applied to the prediction of rain attenuation in equatorial and tropical regions. The model generates a long-term rain attenuation Cumulative Distribution Functions (CDF) that separately accounts for stratiform and convective precipitation. The model assessment in estimating attenuation...
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