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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Preliminary Statistics from the NASA Alphasat Beacon Receiver in Milan, Italy

NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 GHz band. NASA GRC has developed and installed a KQ-band (20-40 GHz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20-40 GHz signals broadcast from the Alphasat Aldo Paraboni TDP5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we provide an overview of the design and data calibration procedure, and present 6 months of preliminary statistics of the NASA propagation terminal, which has been installed and operating in Milan since May 2014. The Q-band receiver has demonstrated a dynamic range of 40 dB at an 8-Hz sampling rate. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models

Radio Transmission↗
NASA NTRS2015

Preliminary Statistics from the NASA Alphasat Beacon Receiver in Milan, Italy

NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have initiated a joint propagation campaign within the framework of the Alphasat propagation experiment to characterize rain attenuation, scintillation, and gaseous absorption effects of the atmosphere in the 40 gigahertz band. NASA GRC has developed and installed a K/Q-band (20/40 gigahertz) beacon receiver at the POLIMI campus in Milan, Italy, which receives the 20/40 gigahertz signals broadcast from the Alphasat Aldo Paraboni TDP no. 5 beacon payload. The primary goal of these measurements is to develop a physical model to improve predictions of communications systems performance within the Q-band. Herein, we provide an overview of the design and data calibration procedure, and present 6 months of preliminary statistics of the NASA propagation terminal, which has been installed and operating in Milan since May 2014. The Q-band receiver has demonstrated a dynamic range of 40 decibels at an 8-hertz sampling rate. A weather station with an optical disdrometer is also installed to characterize rain drop size distribution for correlation with physical based models.

RF propagation↗
NASA NTRS2018

Three Years of Atmospheric Characterization at Ka/Q-band with the NASA/POLIMI Alphasat Receiver in Milan, Italy

Since June of 2014, NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have jointly conducted a propagation campaign within the framework of the Alphasat propagation experiment through a propagation terminal at the POLIMI campus in Milan, Italy. The terminal utilizes the 20 GHz and 40 GHz beacons broadcast by the Aldo Paraboni Technology Demonstration Payload (TDP #5), and consists of dual coherent Ka- and Q-band beacon receivers. These provide a direct measurement of the signal attenuation and scintillation and are complemented by concurrent weather instrumentation that provides measurements of the atmospheric conditions at the receiver. The primary goal of these measurements is to improve model predictions of communication system performance at 40 GHz. Over three years of concurrent measurements have now been collected from the terminal, and herein we present a statistical analysis of the results thus far, as well as a summary of recent hardware upgrades to the receivers that were made in September 2017.

Radio Transmission↗
NASA NTRS2018

Three Years of Atmospheric Characterization at Ka/Q-band with the NASA/POLIMI Alphasat Receiver in Milan, Italy

Since June of 2014, NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) have jointly conducted a propagation campaign within the framework of the Alphasat propagation experiment through a propagation terminal at the POLIMI campus in Milan, Italy. The terminal utilizes the 20 GHz and 40 GHz beacons broadcast by the Aldo Paraboni Technology Demonstration Payload (TDP #5), and consists of dual coherent Ka- and Q-band beacon receivers. These provide a direct measurement of the signal attenuation and scintillation and are complemented by concurrent weather instrumentation that provides measurements of the atmospheric conditions at the receiver. The primary goal of these measurements is to improve model predictions of communication system performance at 40 GHz. Over three years of concurrent measurements have now been collected from the terminal, and herein we present a statistical analysis of the results thus far, as well as a summary of recent hardware upgrades to the receivers that were made in September 2017.

Radio Transmission↗
NASA NTRS2019

Comparison of Integrated Digital Radiometer with Concurrent Water Vapor Radiometer using the Alphasat Receivers in Milan, Italy

In June 2014, NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) jointly deployed a pair of coherent 20 GHz and 40 GHz beacon receivers to the POLIMI campus in Milan, Italy to characterize the atmospheric channel at Ka- and Q-band within the framework of the Alphasat experiment. The Milan receivers observe the continuous-wave beacons broadcast over Europe by the Aldo Paraboni Technology Demonstration Payload (TDP #5), and, in September 2017, both channels were upgraded to incorporate a novel digital radiometer (DR) measurement which NASA has recently employed in other propagation measurement campaigns. In November 2016, a co-located water vapor radiometer (WVR) was also installed at POLIMI, and the concurrent data from both the WVR and DR thusly enables validation of this new DR technique against the established WVR. Herein, we preliminarily investigate the calibration of the DR measurements using the WVR data and also assess a calibration method that may be implemented where WVR data is not readily available.

Zemba, Michael J.↗
NASA NTRS2019

Comparison of Integrated Digital Radiometer with Concurrent Water Vapor Radiometer Using the Alphasat Receivers in Milan, Italy

In June 2014, NASA Glenn Research Center (GRC) and the Politecnico di Milano (POLIMI) jointly deployed a pair of coherent 20 GHz and 40 GHz beacon receivers to the POLIMI campus in Milan, Italy to characterize the atmospheric channel at Ka- and Q-band within the framework of the Alphasat experiment. The Milan receivers observe the continuous-wave beacons broadcast over Europe by the Aldo Paraboni Technology Demonstration Payload (TDP #5), and, in September 2017, both channels were upgraded to incorporate a novel digital radiometer (DR) measurement which NASA has recently employed in other propagation measurement campaigns. In November 2016, a co-located water vapor radiometer (WVR) was also installed at POLIMI, and the concurrent data from both the WVR and DR thusly enables validation of this new DR technique against the established WVR. Herein, we preliminarily investigate the calibration of the DR measurements using the WVR data and also assess a calibration method that may be implemented where WVR data is not readily available.

Zemba, Michael↗
NASA NTRS2021

Late Glacial and Holocene Environmental Variability, Lago Trasimeno, Italy

Lago Trasimeno (central Italy), 10 km wide and < 6m deep, fills a basin of tectonic origin, and is one of Europe's few endorheic lakes. We report on a multidisciplinary stratigraphic study based on seismic reflection profiles and two sediment cores, aimed at providing information on the vegetational, lithological, and climate history of this area. Trace elements, palynology, macrofossils, organic carbon, and C isotopes, coupled with AMS C-14 dating, describe environmental changes from Late-Glacial to present. The base of the cores records a Late-Glacial steppic vegetation (Poaceae, Artemisia, Amaranthaceae), with dry and cold conditions and a high charcoal/pollen ratio. An ensuing shift to a warmer and moister climate is shown by the rise of Pinus and Quercus, and shallow water aquatics such as Nitella. Early Holocene warming, indicated by Quercus, Oleaceae, Corylus, and Betula, is followed by a hiatus suggesting one or more severe drought events between 9000 and 3000 yr BP. Late Holocene presence of Alnus and Fagus indicates increased moisture, probably in winter, which would have increased lake level. Heavy metal pollution indicators (Pb, Cu, Zn) in the upper portion of the cores imply industrialization. Due to its location, to intensive and uninterrupted anthropogenic impacts since proto historical times, and to its shallow depths, Lago Trasimeno provides an important observation point for climate and environmental changes in the central Mediterranean region during and before Holocene times.

Lago trasimeno↗
NASA NTRS2024

The INAF Campo Imperatore Observatory in Abruzzo (Italy) as an Earth Observation Facility for the Study of Venus Night Airglows (VNAs)

The National Institute for Astrophysics (INAF) Campo Imperatore Observatory is located in the Gran Sasso mountains in Abruzzo, Italy, at an altitude of 2150 m above the sea level. The atmospheric transparency, along with the climatic conditions - especially in winter - have always made it a suitable site for observations in the near infrared (1 - 2 micron). The Campo Imperatore Observatory is equipped with the AZT-24 reflecting telescope, Ritchey-Chrétien configuration, with an aperture of 1.1 m. The new motorization system – currently in the commissioning phase - will allow great pointing and tracking accuracy (<0.1 arcsec), as well as an uncommonly fast-tracking speed (the mechanics is designed to reach 3 degrees/second). With this facility we are starting the ADvanced VENus’ Night Airglows Near-infrared Telescope (ADVENANT) project, which aims to observe and study Venus’ nightside airglows (VNAs).

P. D'Incecco↗
NASA NTRS1972

Earth's magnetospheric processes; Proceedings of the Symposium, Cortina, Italy, August 30-September 10, 1971.

New data obtained by satellites, rockets, aircraft, and ground-based observations are interpreted in papers dealing with the magnetospheric structure and processes, particle distributions, magnetic and electric fields, plasma convection, particle acceleration and diffusion mechanisms, and substorm phenomena. Attention is given to particle populations in different magnetospheric regions, auroral particle precipitation patterns, effects of electric fields on plasma convection, VLF phenomena, a high-energy proton model for the inner radiation belt, substorm behavior of plasma sheet particles, and interpretations of magnetic field variations during substorms. Individual items are announced in this issue.

Mccormac, B. M.↗
NASA NTRS1974

Photoballistics of volcanic jet activity at Stromboli, Italy

Two night eruptions of the volcano Stromboli were studied through 70-mm photography. Single-camera techniques were used. Particle sphericity, constant velocity in the frame, and radial symmetry were assumed. Properties of the particulate phase found through analysis include: particle size, velocity, total number of particles ejected, angular dispersion and distribution in the jet, time variation of particle size and apparent velocity distribution, averaged volume flux, and kinetic energy carried by the condensed phase. The frequency distributions of particle size and apparent velocities are found to be approximately log normal. The properties of the gas phase were inferred from the fact that it was the transporting medium for the condensed phase. Gas velocity and time variation, volume flux of gas, dynamic pressure, mass erupted, and density were estimated. A CO2-H2O mixture is possible for the observed eruptions. The flow was subsonic. Velocity variations may be explained by an organ pipe resonance. Particle collimation may be produced by a Magnus effect.

Chouet, B.↗
NASA NTRS1975

Results of Skylab investigation over Italy

The author has identified the following significant results. Multispectral high resolution photography of S190A was successfully applied to the detection of paleoriverbeds in flat lands. Results of SL-3 mission were compared to those of LANDSAT for two regional geological surveys (linear structures) on the islands of Sicily and Sardinia. On Sicily, the seasonal conditions were unfavorable for Skylab while LANDSAT played a major role in discovering long, unknown lineaments of great interest for the geodynamics of the area. On Sardinia, owing to the vegetation type and to the geomorphic conditions, the Skylab imagery was successfully employed to describe the network of linears, both regional and local. Results can be used to study the relationship between linears, actual fracturing and the occurrence of mineral deposits.

Cassinis, R.↗
NASA NTRS1976

Agricultural resources investigations in northern Italy and southern France (Agreste project). Part 1: Activity performed on the Italian test-sites

The author has identified the following significant results. Some qualitative results were obtained out of the experiment of reflectance measurements under greenhouse conditions. An effort was made to correlate phenological stages, production, and radiometric measurements. It was found that the first order effect of exposure variability to sun irradiation is responsible for different rice productivity classes. Effects of rice variety and fertilization become second order, because they are completely masked by the first order effects.

Megier, J.↗