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Visar resultat 1 - 5 av 231 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Phase Modulation Techniques for On-Off Keying in Optical Fibre Transmission

    Författare :Marco Forzati; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; return-to-zero; fibre optics communication; phase modulation; nonlinear optics; dispersion management; high-speed optical transmission; modulation formats; fibres;

    Sammanfattning : Increasing the channel bit rate is an efficient way to upgrade traffic capacity in installed transmission links. At bit rates of the order of 40 Gb/s, on-off keying (OOK) transmission becomes severely impaired by non-linear effects especially Intra-channel Four-Wave Mixing (IFWM) which limit the power at which the signal can be transmitted, and ultimately the transmission distance. LÄS MER

  3. 2. High-efficiency Power Amplification Techniques for Wireless Transmitters

    Författare :Hossein Mashad Nemati; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; load modulation; LDMOS; supply modulation; GaN HEMT; Power amplifier; wireless communications.; GaAs mHEMT; efficiency;

    Sammanfattning : The low efficiency of existing power amplifiers (PAs) is causing excessive energy consumption in wireless systems. Improving the PA efficiency is therefore of great environmental and economical importance. LÄS MER

  4. 3. Control, Modulation and Implementation of Modular Multilevel Converters

    Författare :Antonios Antonopoulos; Hans-Peter Nee; Colin Oates; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Modular Multilevel Converter; Modulation; Feedback Control; Open-Loop Control; Implementation; Prototype; High-Performance Motor Drives; Electrical engineering; electronics and photonics; Elektroteknik; elektronik och fotonik;

    Sammanfattning : Denna avhandling behandlar analys och styrning av den modulära multinivå omvandlaren (M2C). M2C är en lovande omvandlarteknologi för högspända högeffekttillämpningar. Anledningen till detta är låg distorsion i utstorheterna kan uppnås med låg  medelswitchfrekvens per switch och utan utgångsfilter. LÄS MER

  5. 4. Fibre-Optic Displacement and Temperature Sensing Using Coupling Based Intensity Modulation and Polarisation Modulation Techniques

    Författare :Johan Jason; Hans-Erik Nilsson; Bertil Arvidsson; Werner Daum; Mittuniversitetet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; optical fibre sensor; displacement measurement; temperature measurement; fibre coupling; intensity modulation; birefringence; polarisation; OTDR; side-hole fibre;

    Sammanfattning : Optical fibre sensors are employed in the measurements of a number of different physical properties or for event detection in safety and security systems. In those environments which suffer from electromagnetic disturbance, in harsh environments where electronics cannot survive and in applications in favour of distributed detection, fibre-optic sensors have found natural areas of use. LÄS MER

  7. 5. Coded Modulation Techniques in Fiber-Optical Communications

    Författare :Lotfollah Beygi; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : Today's high demand for increasing the data transmission rate motivates a great challenge to improve the spectral efficiency of fiber-optical channels. In order to achieve a higher spectral efficiency, exploiting an advanced coded modulation scheme is inevitable. LÄS MER