Search results for "raptor"

showing 10 items of 42 documents

Rateless codes mitigation technique in a turbulent indoor Free Space Optics link

2014

Free Space Optics (FSO) links are affected by several impairments and, among them, optical turbulence is the most important factor that can degrade the link quality. Due to the presence of this phenomenon, the signal irradiance detected by the receiver fluctuates, thus causing erasure errors and fading events. In this work, we present an indoor Free Space Optics link, in which several turbulence conditions are generated by using two heating elements. We show that the generated turbulence causes erasure errors and packet losses during the data transmission, and we also compare the statistical distribution of the samples with the theoretical models. Moreover, we demonstrate how the applicatio…

PhysicsNetwork packetSettore ING-INF/03 - TelecomunicazioniEncoding (memory)Electronic engineeringBit error rateErasureFadingSettore ING-INF/01 - ElettronicaDecoding methodsFree Space Optics (FSO) optical turbulence rateless codes RaptorQFree-space optical communicationData transmission
researchProduct

Moderate-to-Strong Turbulence Generation in a Laboratory Indoor Free Space Optics Link and Error Mitigation via RaptorQ Codes

2016

Free Space Optics (FSO) is rapidly gaining interest as a line-of sight communication technology that offers capabilities similar - in terms of bandwidth and transfer rates - to optical fibre, also possessing several advantages compared with traditional radio frequency links. However, FSO link quality can be strongly affected by unfavourable weather conditions and also by the phenomenon of optical turbulence, even in clear sky. In this work, we have implemented an indoor FSO link and generated moderate-to-strong turbulence conditions along the optical path by using heaters and a mechanical ventilation system. In this way, we have been able to investigate the effects of the generated turbulen…

Physicsbusiness.industryNetwork packetFree Space Optics (FSO) indoor link turbulence generation packet loss rateless codes RaptorQ codesSettore ING-INF/03 - Telecomunicazioni05 social sciencesBandwidth (signal processing)050801 communication & media studies020206 networking & telecommunicationsSettore ING-INF/02 - Campi Elettromagnetici02 engineering and technologySettore ING-INF/01 - ElettronicaData recovery0508 media and communicationsOptical path0202 electrical engineering electronic engineering information engineeringBit error rateElectronic engineeringRadio frequencybusinessAdaptive opticsFree-space optical communication
researchProduct

Rateless Codes Performance Tests On Terrestrial FSO Time-Correlated Channel Model

2012

Free Space Optics (FSO) links are affected by several impairments: optical turbulence, scattering, absorption, and pointing. In particular, atmospheric optical turbulence generates optical power fluctuations at the receiver that can degrade communications with fading events, especially, in high data rate links. A way to mitigate FSO link outages can be to add a coding to communications. Nevertheless, in order to study innovative solutions (software or hardware) and to improve the FSO link performance it needs accurate testing models. In this paper we describe an accurate time-correlated channel model able to predict random temporal fluctuations of optical signal irradiance caused by optical…

Physicsbusiness.industrySettore ING-INF/03 - Telecomunicazionicorrelated channelrateless code.Fountain codeOptical powerSettore ING-INF/02 - Campi ElettromagneticiOptical performance monitoringRaptorQ (RQ)Settore ING-INF/01 - ElettronicaSoftwareFree Space Optics (FSO)Luby Tranform (LT)Electronic engineeringFadingbusinessRaptor codeTransform codingAtmospheric opticsComputer Science::Information TheoryCoding (social sciences)Free-space optical communication
researchProduct

Rateless codes implementation, optimization and application to Free Space Optics links affected by optical turbulence

In this work, I have implemented, optimized and tested the most advanced rateless codes available up to now, i.e., RaptorQ codes. In detail, a multiplatform data transmission software has been appositely developed in order to verify the effectiveness of the above-mentioned codes to decrease packet loss and hence to improve the link quality, under different network and channel conditions. Several simulative and experimental investigations have been carried out to evaluate the performance of the encoding and decoding schemes and the relative recovery capabilities under different test scenarios. In particular, I have applied the software embedding RaptorQ codes to Free Space Optics communicati…

RaptorQ codesoptical turbulenceFree Space Opticrateless codeGamma-Gamma modelSettore ING-INF/01 - Elettronica
researchProduct

Towards a European raptor specimen bank in support of contaminant research and monitoring for better chemicals management

Raptors museum collections contaminantSettore BIO/05 - Zoologia
researchProduct

Holidays? Not for all. Eagles have larger home ranges on holidays as a consequence of human disturbance

2019

Human-wildlife conflicts are the object of raising concern in conservation biology. People living in urban areas are rapidly increasing worldwide and consequently the temporal pattern of occupation of natural areas for recreation is changing as well, resulting in an ever-increasing concentration of people during weekends and holidays. This is particularly evident in affluent societies, where more recreationists visit natural areas on holidays and weekends, causing disturbance to wildlife in the so-called “weekend effect”. Here, we tested the response to disturbance of 30 Bonelli's eagles tracked by high-frequency GPS/GSM telemetry. We analysed daily home-range size, a measure of changing be…

Recreational activities0106 biological sciencesRaptorsWeekend effectGPS010604 marine biology & hydrobiologyWildlifeConservationAnnual cycleOutdoor activities010603 evolutionary biology01 natural sciencesGeographyNestDisturbance (ecology)Human disturbanceSpace useTelemetryZoologíaConservation biologySocioeconomicsQuality informationRecreationEcology Evolution Behavior and SystematicsNature and Landscape ConservationBiological Conservation
researchProduct

Citizen science project to monitor wildlife: a first census of wintering Booted Eagle Hieraaetus pennatus in Sicily

2022

Citizen science can represent an effective tool for large- scale data collection and can be used to improve scientific knowledge and define species distribution ranges before proper planning of related conservation strategies. A regional census of wintering Booted Eagle Hieraaetus pennatus in Sicily, never achieved before, was organized by GAM (Gruppo Aquila Minore - Booted Eagle Group) on 12 Janu- ary 2020, involving 90 people from several organizations. A total of 112 wintering individuals have been recorded for the whole region, col- lecting related data about their colour morph, habitat preference and altitude. A regional estimate of 180-220 wintering individuals was cal- culated, also …

Settore BIO/05 - ZoologiaCitizen science counting raptors wintering popula- tion
researchProduct

Breeding abundance of threatened raptors as estimated from occurrence data

2008

A model derived from the negative binomial distribution (NBD) has been proposed to solve the problem of predicting abundance of species from occurrence maps. The viability of NBD was explored for predicting the breeding abundance of five threatened species of raptor: Bonelli's Eagle Hieraaetus fasciatus, Golden Eagle Aquila chrysaetos, Peregrine Falco peregrinus, Lanner Falco biarmicus and Lesser Kestrel Falco naumanni. First, the accuracy of the NBD was tested in a reference area where the species abundance and occurrence were known through intensive field surveys. Next, an estimation of regional abundance derived from NBD was made for each species. These estimates were then compared to th…

Settore BIO/05 - Zoologiadistribution atlaseagle falcon raptor modelling negative binomial distribution
researchProduct

Rateless Codes Performance Analysis in Correlated Channel Model for GEO Free Space Optics Downlinks

2012

Settore ING-INF/03 - TelecomunicazioniFree Space Optics (FSO) technologies for satellite communications offer several advantages: wide bandwidth high rate capability immunity to electromagnetic interference and small equipment size. Thus they are suitable for inter-satellite links deep space communications and also for high data rate ground-to-satellite/satellite-to-ground communications. Nevertheless FSO links suffer impairments that cause power signal degradation at the receiver. Scattering and absorption cause power signal attenuations predictable by suitable deterministic models. Optical turbulence causes random irradiance fluctuations which can generate signal fading events and can thereby only be predicted by statistical models. Attenuation and fading events can corrupt FSO links and so it would be recommended to add mitigation error codes on the communication link. FSO channel can be described as an erasure channel: fading events can cause erasure errors. We have identified in rateless codes (RCs) a suitable solution to be employed in FSO links. RCs do not need feedback and they add a redundant coding on the source data that allows the receiver to recover the whole payload despite erasure errors. We implemented two different of rateless codes: Luby Transform (LT) and Raptor. We analyzed their performances on a simulated turbulent GEO FSO downlink (1 Gbps - OOK modulation) at a 106 μm wavelength and for different values of zenith angles. Assuming a plane-wave propagation and employing Hufnagel-Valley we modeled the downlink using: 1) a temporal correlated channel model based on Gamma-Gamma probability distribution and 2) an irradiance covariance function that we converted on a time function using Taylor frozen eddies hypothesis. Our new channel model is able to simulate irradiance fluctuations at different turbulence conditions as it will be shown in the full paper. We will also report performance results of LT and Raptor codes at overhead range varying between 0 and 50% and for different values of source packets.Settore ING-INF/01 - Elettronica
researchProduct

Correlated channel model for terrestrial Free Space Optics: performance analysis of rateless codes

2012

We describe a novel correlated channel model able to predict random temporal fluctuations of optical signal irradiance caused by scintillation. With regards to the same channel, we also report simulation results on the error mitigation performance of Luby-Transform and Raptor codes.

Settore ING-INF/03 - TelecomunicazioniFree Space Optics channel modeling Raptor codes RaptorQ codes LT codes rateless codesSettore ING-INF/02 - Campi ElettromagneticiSettore ING-INF/01 - Elettronica
researchProduct