Search results for "Optical communication"

showing 10 items of 92 documents

Mapping Carbon Stocks In Central And South America With Smap Vegetation Optical Depth

2019

Mapping carbon stocks in the tropics is essential for climate change mitigation. Passive microwave remote sensing allows estimating carbon from deep canopy layers through the Vegetation Optical Depth (VOD) parameter. Although their spatial resolution is coarser than that of optical vegetation indices or airborne Lidar data, microwaves present a higher penetration capacity at low frequencies (L-band) and avoid cloud masking. This work compares the relationships of airborne carbon maps in Central and South America with both (i) SMAP L-band VOD at 9 km gridding and (ii) MODIS Enhanced Vegetation Index (EVI). Models to estimate carbon stocks are built from these two satellite-derived variables.…

CanopyL bandTeledetecció010504 meteorology & atmospheric sciencesRadiofreqüència0208 environmental biotechnologyClimate changeOptical radar02 engineering and technology01 natural sciencesComunicacions òptiquesCarboniImage resolution0105 earth and related environmental sciencesRemote sensingVegetation mappingVegetationOptical communicationsTropicsEnhanced vegetation indexRemote sensing:Enginyeria de la telecomunicació [Àrees temàtiques de la UPC]Carbon020801 environmental engineering:Enginyeria de la telecomunicació::Telecomunicació òptica [Àrees temàtiques de la UPC]Climate change mitigationRemote sensing by laser beamSpatial ecologyEnvironmental scienceSistemes de gestió mediambientalIGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium
researchProduct

Robustness of 40 Gb/s ASK modulation formats in the practical system infrastructure.

2006

In this work, we analyzed by means of numerical and laboratory experiments the resilience of 40 Gb/s amplitude shift keying modulation formats to transmission impairments in standard single-mode fiber lines as well as to optical filtering introduced by the optical add/drop multiplexer cascade. Our study is a pre-requisite to assess the implementation of cost-effective 40 Gb/s modulation technology in next generation high bit-rate robust optical transport networks. © 2006 Optical Society of America.

Computer scienceOptical communication02 engineering and technologyOptical modulation amplitude01 natural sciencesMultiplexerMultiplexing010309 optics020210 optoelectronics & photonicsOpticsOptical Transport Network0103 physical sciences0202 electrical engineering electronic engineering information engineeringcost effectiveness; frequency shift keying; multiplexingFiberOptical add-drop multiplexerbusiness.industryOptical cross-connectNonlinear opticsOptical performance monitoringAtomic and Molecular Physics and OpticsAmplitude-shift keyingRaman amplifiersModulationPolarization mode dispersionBit error ratebusinessOptics express
researchProduct

Tunable and reconfigurable microwave filter by use of a Bragg-grating-based acousto-optic superlattice modulator

2005

We present an all-optical novel configuration for implementing multitap transversal filters by use of a broadband source sliced by fiber Bragg grating arrays generated by propagating an acoustic wave along a strong uniform fiber Bragg grating. The tunability and reconfigurability of the microwave filter are demonstrated.

Condensed Matter::Quantum GasesPhysicsSignal processingOptical fiberbusiness.industryOptical communicationPhysics::OpticsReconfigurabilityAcoustic waveAtomic and Molecular Physics and Opticslaw.inventionOpticsFiber Bragg gratinglawBroadbandbusinessDiffraction gratingOptics Letters
researchProduct

Recovery Capabilities of Rateless Codes on Simulated Turbulent Terrestrial Free Space Optics Channel Model

2013

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. Innovative solutions require an improvement of FSO link performances, together with testing models and appropriate channel codes. In this paper, we describe a high-resolution time-correlated channel model able to predict random temporal fluctuations of optical signal irradiance caused by optical turbulence. Concerning the same channel, we also report simulation results on the error mi…

EngineeringArticle SubjectIrradianceOptical powerSettore ING-INF/01 - ElettronicaSignaloptical turbulenceElectronic engineeringFadingElectrical and Electronic Engineeringtime-serieComputer Science::Information TheorySettore ING-INF/03 - TelecomunicazioniTurbulenceScatteringbusiness.industryRateless codesSettore ING-INF/02 - Campi Elettromagneticilcsh:HE9713-9715Free Space Opticlcsh:Cellular telephone services industry. Wireless telephone industrylcsh:Electrical engineering. Electronics. Nuclear engineeringbusinesslcsh:TK1-9971Communication channelFree-space optical communicationInternational Journal of Antennas and Propagation
researchProduct

Logical and pseudo-logical optical fibre networks based on two-state (binary) optical fibre sensors for industrial monitoring and control systems

2005

The possibilities of development of logical and pseudo-logical optical fibre networks for monitoring and control of equipment and industrial sites are presented. Such networks composed of simple binary attenuation and optical fibre communication lines may also be used as fast and reliable systems developing a final command signal - logical and/or pseudo-logical, depending or the architecture of network and the type of located sensors. They realise the process similar to standard electronic logical sets but use the optical signal directly on the monitored or controlled device. The analysis of serial and parallel networks was carried out in the "dark" mode detection. The examples of networks …

EngineeringLogical conjunctionFiber optic sensorbusiness.industryComputer Science::Logic in Computer ScienceControl systemProcess (computing)Electronic engineeringOptical communicationBinary numberState (computer science)businessSignalSPIE Proceedings
researchProduct

<title>Evolution of optical links toward full-optical transparency</title>

2003

In this paper we review issues of evolution of optical networks towards their full optical transparency and present sequence of eliminating non-transparent elements out of optical links (networks). Architectures of optical commutators with electrical and optical cores have been presented, as well as a structure of OMO (optical-millimeter wave-optical) switching fabric. An example of pure al-optical switch, made by Luxcore, utilizing dispersion compensating elements, wavelength converters and and variable optical attenuators (VOA) operating entirely in optical domain without optical-electrical-optical (OEO) conversions, was quoted. We brought up an issue of all-optical 3R signal regeneration…

EngineeringOptical Transport Networkbusiness.industryOptical cross-connectOptical transistorElectronic engineeringPhysics::OpticsOptical performance monitoringbusinessOptical switchOptical add-drop multiplexerSignal regenerationOptical communications repeaterSPIE Proceedings
researchProduct

Ultra-Wideband Radio Signals Distribution in FTTH Networks

2008

[EN] The use of an ultra-wideband (UWB) radio technique is proposed as a viable solution for the distribution of high-definition audio/video content in fiber-to-the-home (FTTH) networks. The approach suitability is demonstrated by the transmission of standards-based UWB signals at 1.25 Gb/s along different FTTH fiber links with 25 km up to 60 kin of standard single-mode fiber length in a laboratory experiment. Experimental results suggest that orthogonal frequency-division-multiplexed UWB signals exhibit better transmission performance in FFTH networks than impulse radio UWB signals.

EngineeringOptical communicationsbusiness.industryAccess networks Ultra-Wide Band (UWB).Optical communicationUltra-widebandFiber-To-The-Home (FTTH)Transmission performanceAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic MaterialsTelecomunicacióRadio over fiberTransmission (telecommunications)TEORIA DE LA SEÑAL Y COMUNICACIONESElectronic engineeringElectrical and Electronic EngineeringLaboratory experimentbusinessComunicació i tecnologiaImpulse radio
researchProduct

Combined Analysis of OFDM-UWB Transmission in Hybrid Wireless-Optical Access Networks

2009

[EN] The hybrid wireless-optical transmission of ultra-wideband signals employing orthogonal frequency-division multiplexing modulation (OFDM) ultra-wideband (UWB) as defined in the ECMA-368 standard is experimentally analyzed in this letter. The OFDM-UWB signals provide 400 Mb/s per user at optical distances from 5 to 50 km on standard single-mode fiber (SSMF). The analysis includes the wireless radiation from 0 to 3 m after optical transmission. The results indicate a maximum error-vector-magnitude degradation of 2.5 dB measured at 1.5-m radio after 50-km SSMF optical transmission for the first two UWB channels. This degradation translates to 1-m maximum wireless-reach penalty.

EngineeringOrthogonal frequency-division multiplexingOptical communication02 engineering and technology01 natural sciencesMultiplexingTelecomunicació010309 optics020210 optoelectronics & photonicsTEORIA DE LA SEÑAL Y COMUNICACIONES0103 physical sciences0202 electrical engineering electronic engineering information engineeringElectronic engineeringWirelessElectrical and Electronic EngineeringComunicació i tecnologiaFiber-to-the-home (FTTH) networksOptical access networksAccess networkOptical communicationsbusiness.industrySingle-mode optical fiberAtomic and Molecular Physics and OpticsElectronic Optical and Magnetic MaterialsTransmission (telecommunications)Ultra-wideband (UWB)ModulationbusinessIEEE Photonics Technology Letters
researchProduct

Packet loss recovery in an indoor Free Space Optics link using rateless codes

2014

Free Space Optics (FSO) systems present some important advantages if compared to Radio Frequency links, but they can be affected by several impairments that degrade the link quality and availability. In particular, due to temporary interruptions of the line-of-sight condition between the transmitter and the receiver, packet loss can occur during data transmission. In this work, we present an indoor Free Space Optics link, in which we have systematically generated interruptions of the beam. We demonstrate how the application of the most recent rateless codes, i.e., RaptorQ codes, can strongly improve the link quality by reducing packet loss. In particular, results show that the Packet Error …

EngineeringSettore ING-INF/03 - TelecomunicazioniNetwork packetbusiness.industryTransmitterFree Space Optics (FSO) packet loss rateless codes RaptorQSettore ING-INF/01 - ElettronicaPacket lossEncoding (memory)Electronic engineeringBit error ratebusinessDecoding methodsFree-space optical communicationData transmission2014 16th International Conference on Transparent Optical Networks (ICTON)
researchProduct

<title>Safety problems in free space optical transmission</title>

2006

The paper is focused on safety of exploitation of optical transmission devices in free space. The subjects concerning propagation of "open" optical stream and its' possible dangerous influence on environment, mainly living organisms are discussed. An attempt to evaluate an installation and exploitation of transmitting devices was made, concerning dangers, requirements, recommendations and restrictions, concluding from accepted safety standards (IEC 60825- 1 :2005, EN 60825-1 :2005 and in Poland PN-EN 60825-1 :2005 "Safety of laser devices - Equipment classification, requirements and user's guide"; IEC 60825-12:2004, EN 60825-12:2005 and in Poland PN-EN 60825-12:2005 "Safety of free space op…

EngineeringTransmission (telecommunications)Laser safetybusiness.industryFree spaceSafety standardsbusinessTelecommunicationsData transmissionFree-space optical communicationSPIE Proceedings
researchProduct