Towards coordinated site monitoring and common strategies for mitigation of Radio Frequency Interference at the Italian radio telescopes

We present a project to implement a national common strategy for the mitigation of the steadily deteriorating Radio Frequency Interference (RFI) situation at the Italian radio telescopes. The project involves the Medicina, Noto, and Sardinia dish antennas and comprised the definition of a coordinated plan for site monitoring as well as the implementation of state-of-the-art hardware and software tools for RFI mitigation. Coordinated monitoring of frequency bands up to 40 GHz has been performed by means of continuous observations and dedicated measurement campaigns with fixed stations and mobile laboratories. Measurements were executed on the frequency bands allocated to the radio astronomy and space research service for shared or exclusive use and on the wider ones employed by the current and under-development receivers at the telescopes. Results of the monitoring campaigns provide a reference scenario useful to evaluate the evolution of the interference situation at the telescopes sites and a case series to test and improve the hardware and software tools we conceived to counteract radio frequency interference. We developed a multi-purpose digital backend for high spectral and time resolution observations over large bandwidths. Observational results demonstrate that the spectrometer robustness and sensitivity enable the efficient detection and analysis of interfering signals in radio astronomical data. A prototype off-line software tool for interference detection and flagging has been also implemented. This package is capable to handle the huge amount of data delivered by the most modern instrumentation on board of the Italian radio telecsopes, like dense focal plane arrays, and its modularity easen the integration of new algorithms and the re-usability in different contexts or telescopes.Comment: 39 pages, 10 Figures and 7 Tables. INAF Technical Report n. 149 (2022). http://hdl.handle.net/20.500.12386/3208

Space shuttle electromagnetic environment experiment. Phase A: Definition study

Methods for carrying out measurements of earth electromagnetic environment using the space shuttle as a measurement system platform are herein reported. The goal is to provide means for mapping intentional and nonintentional emitters on earth in the frequency range 0.4 to 40 GHz. A survey was made of known emitters using available data from national and international regulatory agencies, and from industry sources. The spatial distribution of sources, power levels, frequencies, degree of frequency re-use, etc., found in the survey, are here presented. A concept is developed for scanning the earth using a directive antenna whose beam is made to rotate at a fixed angle relative to the nadir; the illuminated area swept by the beam is of the form of cycloidal annulus over a sphere. During the beam's sojourn over a point, the receiver sweeps in frequency over ranges in the order of octave width using sweeping filter bandwidths sufficient to give stable readings

Space shuttle electromagnetic environment experiment. Phase A: Definition study

A program is discussed which develops a concept for measuring the electromagnetic environment on earth with equipment on board an orbiting space shuttle. Earlier work on spaceborne measuring experiments is reviewed, and emissions to be expected are estimated using, in part, previously gathered data. General relations among system parameters are presented, followed by a proposal on spatial and frequency scanning concepts. The methods proposed include a nadir looking measurement with small lateral scan and a circularly scanned measurement looking tangent to the earth's surface at the horizon. Antenna requirements are given, assuming frequency coverage from 400 MHz to 40 GHz. For the low frequency range, 400-1000 MHz, a processed, thinned array is proposed which will be more fully analyzed in the next phase of the program. Preliminary hardware and data processing requirements are presented

Proceedings of the Fifteenth NASA Propagation Experimenters Meeting (NAPEX 15) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

The NASA Propagation Experimenters Meeting (NAPEX), supported by the NASA Propagation Program, is convened annually to discuss studies made on radio wave propagation by investigators from domestic and international organizations. The meeting was organized into three technical sessions. The first session was dedicated to Olympus and ACTS studies and experiments, the second session was focused on the propagation studies and measurements, and the third session covered computer-based propagation model development. In total, sixteen technical papers and some informal contributions were presented. Following NAPEX 15, the Advanced Communications Technology Satellite (ACTS) miniworkshop was held on 29 Jun. 1991, to review ACTS propagation activities, with emphasis on ACTS hardware development and experiment planning. Five papers were presented

Radio Frequency Interference /RFI/ design guide for aerospace communications systems

Radio frequency interference design guide for aerospace communications system

Telecommunications for a deregulated power industry

Telecommunication plays a very important role in the effective monitoring and control of the power grid. Deregulation of the US power industry has enabled utilities to explore various communication options and advanced technologies. Utilities are increasingly investing in distributed resources, dynamic real-time monitoring, automated meter reading, and value added services like home energy management systems and broadband access for its customers. Telecommunication options like power line communications (PLC) and satellites are fast replacing legacy telephone and microwave systems in the US.;The objective of this thesis is to study the communication options that are available for utilities today. Phasor measurement units (PMUs) are analyzed in detail and communication delays due to the use of PMUs in wide area measurement systems (WAMS) are also studied. The highlight of this thesis is a close look at the characteristics of the power line channel by presenting a power line channel model and the use of digital modulation techniques like SS and OFDM, which help overcome the effects of such a hostile medium of communication. (Abstract shortened by UMI.)

Ultra Wideband Preliminaries

Non

The evolution of a Ku-Band satellite network

The purpose of this study was to undertake the management and development of CTS terminals and time on appropriate Ku-Band satellites was procured. A community of public service users who have readily addressable needs and resources to pay for services on an ad hoc Ku-Band network was developed and a test network for selected users was managed

Ultra wideband gigabit powerline communication

PhDPowerline Communication (PLC) has long been established for low data rate applications by the electric supply companies. Since 1991, the European CENELEC standard EN 50065 has ruled the use of 3 - 148.5KHz frequency range for narrow band PLC applications. Sim- ilar standard has been established by the IEEE in the US, where a frequency range of 50 - 450KHz is available. The fast growth of Internet since the 1990s accelerated the demands for digital communication services. Furthermore, with the develop- ment of in-home networking, there is a need to establish high speed data links between multiple household devices. This makes PLC sys- tems march rapidly into the high frequency range above 1MHz. Exist- ing broadband PLC system in the 1.6 - 30MHz frequency range only provides data rates smaller than 200Mbps. With the growing demand of multimedia services such as High De nition (HD) video streaming, much faster transmission speed up to Gigabits per second is required and this can be achieved by increasing the operating frequencies. Ultra Wideband (UWB) transmission in free space provides extremely broad bandwidth for short-range, high data rate applications. If UWB signals could be transmitted over the powerline channels in the high frequency range above 30MHz, data rates up to gigabits per second could be achieved. In this thesis, the possibility of implementing ultra wideband trans- mission over the low voltage indoor powerline is investigated. The starting point is to understand the signal propagation characteristics over powerline cables, in the UWB frequency range. Experimental re- sults indicate that the signal degrades at an acceptable rate over the mains cable in a scaled down UWB frequency band (50MHz - 1GHz), which provides a potential operation band for UWB over PLC ap- plications. Key component for the PLC system, a broadband Radio Frequency (RF) coupler is designed and developed, to introduce UWB signals to the transmission channel. With the channel properties and coupling unit, extensive experimental investigations are carried out to analyse the powerline network environment, including channel loss, noise and radiated emission. Furthermore, theoretical channel capac- ity and link budget are derived from measured parameters. It is shown that the indoor powerline is a suitable media for data transmission in the high frequency range from 50 to 550MHz in the home environment. Finally, system level performance is analysed by modelling the Phys- ical Layer (PHY) data transmission. The Multiband-OFDM UWB proposal for IEEE 802.15.3a standard is used to predict the transmis- sion performance under di erent propagation paths and data rates. The research work conducted in this project has proven that UWB over PLC is highly feasible for future in-home applications. With the global promotion of smart grid applications, UWB over PLC will play an important role in providing high speed data transmission over the power networks