Sökning: "pulse amplitude modulation"

Visar resultat 21 - 25 av 29 avhandlingar innehållade orden pulse amplitude modulation.

  1. 21. Voltage source converters for mitigation of flicker caused by arc furnaces

    Författare :Tomas Larsson; KTH; []
    Nyckelord :;

    Sammanfattning : The thesis deals with flicker and how to mitigate it bymeans of a Voltage Source Converter (VSC). Flicker, orvariations in illumination intensity, is above a certain levelvery annoying. The background to flicker is voltage amplitudefluctuating in certain frequency intervals caused bytime-fluctuating loads. LÄS MER

  3. 22. On the labeling of Signal Constellations

    Författare :Johan Lassing; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : The work in this thesis studies a simple model of a digital communication system in which the transmitter operates on a sequence of information bits by grouping them into blocks of m bits and mapping such blocks onto one out of M = 2m waveforms, which is transmitted over the channel. The receiver recovers the original message by demapping the transmitted signals disturbed by noise back to m-bit blocks using maximum-likelihood symbol detection. LÄS MER

  4. 23. On High-Speed Digital-to-Analog Converters and Semi-Digital FIR Filters

    Författare :Mohammad Reza Sadeghifar; J Jacob Wikner; Robert Hägglund; Linköpings universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; DAC; RFDAC; SDFIR; FIR; semi-digital FIR filter; digital-to-analog converter; D A converter; data converter; mixed-signal integrated circuits; mixer DAC; IQ modulator; transmitter;

    Sammanfattning : High-speed and high-resolution digital-to-analog converters (DACs) are vital components in all telecommunication systems. Radio-frequency digital-to-analog converter (RFDAC) provides high-speed and high-resolution conversion from digital domain to an analog signal. RFDACs can be employed in direct-conversion radio transmitter architectures. LÄS MER

  5. 24. Optical Amplifiers and their Applications in Nonlinear Fiber-Optic Communication Systems

    Författare :Kent Bertilsson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

    Sammanfattning : The work presented in this dissertation deals with the characterization and modeling of optical amplifiers as well as their applications in nonlinear transmission systems with the main motivation to enhance system capacity. In the first part of the dissertation the work is focused on two different types of amplifiers: the semiconductor laser amplifier (SLA) and the erbium-doped fiber amplifier (EDFA). LÄS MER

  7. 25. Partial Discharges at Fast Rising Voltages

    Författare :Thomas Hammarström; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; short rise time; cavities; high dV dt.; measurements; Partial discharges; square like voltages; repetitive voltages;

    Sammanfattning : The present demand for higher efficiency and flexibility in the energy sector has led to an increased use of power electronic generated waveforms as these allow energy conversion between different frequencies including DC. The generated waveforms are usually synthesized by so called Pulse Width Modulation (PWM) techniques, where the desired waveform is approximated by a number of square shaped pulses with a short rise time. LÄS MER