Sökning: "Frequency Modulation"

Visar resultat 1 - 5 av 248 avhandlingar innehållade orden Frequency Modulation.

  1. 1. Multicarrier modulation : duplexing design and interference/distortion mitigation

    Författare :Rickard Nilsson; Luleå tekniska universitet; []

    Sammanfattning : Aspects of modern communication systems is the overall theme of this thesis with emphasis placed on multicarrier modulation. The work considers four facets of such systems; namely duplexing design, interference mitigation, channel estimation and multiuser detection. LÄS MER

  2. 2. Low frequency noise during work. Effects on performance and annoyance

    Författare :Johanna Bengtsson; Göteborgs universitet; Göteborgs universitet; Gothenburg University; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Low frequency noise; performance; workload; annoyance; cortisol; subjective stress; subjective sensitivity to noise; sound characteristics; frequency balance; modulation frequency;

    Sammanfattning : Aims. Low frequency noise (LFN) is defined as "a noise with a dominant frequency content of 20 to 200 Hz". Common sources of LFN in occupational environments are ventilation, heating and air-conditioning systems, computer network installations and compressors. LÄS MER

  3. 3. Modeling and Control of Voltage Source Converters Connected to the Grid

    Författare :Michael Lindgren; Chalmers University of Technology; []
    Nyckelord :voltage source converter; switching frequency; pulse width modulation; IGBT valve; power electronics; small-signal; L-filter; LCL-filter; transfer function; line filter; active filtering; frequency response; sampling frequency;

    Sammanfattning : This thesis deals with the modeling and control of pulse width modulated (PWM) voltage source converters connected to the grid. When voltage source converters are connected to the grid, the power quality and the dynamic performance are affected by the line filter connected between the converter and the grid, and by nonlinearities caused by the switching converter. LÄS MER

  4. 4. Modulation of Modular Multilevel Converters for HVDC Transmission

    Författare :Arman Hassanpoor; Hans-Peter Nee; Staffan Norrga; Rainer Marquardt; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; HVDC; switching schemes; modulation; high power converters; power grids; Electrical Engineering; Elektro- och systemteknik;

    Sammanfattning : The outstanding features of modular multilevel converters (MMC) have recently gained much attention in the high-voltage direct-current (HVDC) transmission field. Power quality, converter cost and system performance are three crucial aspects of HVDC MMCs which are directly linked to the converter modulation and switching schemes. LÄS MER

  5. 5. Low Noise Oscillator in ADPLL toward Direct-to-RF All-digital Polar Transmitter

    Författare :Jian Chen; Li-Rong Zheng; Fredrik Jonsson; Hannu Tenhunen; Georges Gielen; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; all-digital; digitally-intensive; frequency modualtion; phase modulation; amplitude modulation; polar; transmitter; oscillator; digital controled oscillator; DCO; VCO; voltage controled oscillator; class-C oscillator; class-D PA; ADPLL; phase noise; RF; CMOS.;

    Sammanfattning : In recent years all-digital or digitally-intensive RF transmitters (TX) have attracted great attention in both literature and industry. The motivation is to implement RF circuits in a manner suiting advanced nanometer CMOS processes. To achieve that, information is encoded in the time-domain rather than voltage amplitude. LÄS MER