Sökning: "line spectral frequency"

Visar resultat 1 - 5 av 42 avhandlingar innehållade orden line spectral frequency.

  1. 1. High spectral efficiency transmission using optical frequency combs

    Författare :Mikael Mazur; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Optical frequency combs; Superchannels; Coherent optical communication;

    Sammanfattning : Modern long-haul optical communication systems transmit data on all available single-mode fiber dimensions, time, polarization, wavelength, phase and amplitude. Powerful digital signal processing and forward error correction has pushed the per-channel throughput towards its theoretical limits and the bandwidth is limited by the erbium-doped fiber amplifiers. LÄS MER

  3. 2. Estimation and detection of transmission line characteristics in the copper access network

    Författare :Fredrik Lindqvist; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Digital subscriber line; DSL; line qualification; twisted-pair line; copper access network; cable modeling; crosstalk channel estimation; estimation; detection;

    Sammanfattning : The copper access-network operators face the challenge of developing and maintaining cost-effective digital subscriber line (DSL) services that are competitive to other broadband access technologies. The way forward is dictated by the demand of ever increasing data rates on the twisted-pair copper lines. LÄS MER

  4. 3. Precision molecular spectroscopy in the near- and mid-infrared using frequency comb-based Fourier transform spectrometers

    Författare :Adrian Hjältén; Aleksandra Foltynowicz; Ove Axner; Adam Fleisher; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; optical frequency comb; molecular spectroscopy; Fourier transform spectrometer; high resolution; mid-infrared; line list; double-resonance spectroscopy; difference frequency generation; fysik; Physics;

    Sammanfattning : Absorption spectroscopy is a powerful scientific tool for non-invasive and remote sensing applications ranging from atmospheric monitoring to astrophysics. In spectroscopic detection schemes it is necessary to have spectral models for any molecular species to be detected or quantified. LÄS MER

  5. 4. Towards Ultimate Performance of THz Heterodyne Receivers: SIS Frequency Multiplier and Wideband Passive Components

    Författare :Hawal Marouf Rashid; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Wideband passive components; distributed SIS junction; Frequency multiplier; Frequency up-converter; Hybrids; distributed SIS frequency multiplier;

    Sammanfattning : This thesis focuses on the development of advanced components for the future wideband side band separating and / or multipixel receivers for radio-astronomy with ultimate sensitivity.In this thesis, a novel frequency multiplier based on distributed superconducting tunnel (SIS) junctions has been demonstrated for the first time, taking advantage of the extreme inherent nonlinearity of such device. LÄS MER

  7. 5. Sparse Modeling of Grouped Line Spectra

    Författare :Ted Kronvall; Statistical Signal Processing Group; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; line spectra; parameter estimation; convex optimization; group-sparsity; block-sparsity; dictionary learning; ADMM; adaptive penalty; total variation; multi-pitch estimation; chroma; audio processing; TDOA; near-field localization; amplitude modulation;

    Sammanfattning : This licentiate thesis focuses on clustered parametric models for estimation of line spectra, when the spectral content of a signal source is assumed to exhibit some form of grouping. Different from previous parametric approaches, which generally require explicit knowledge of the model orders, this thesis exploits sparse modeling, where the orders are implicitly chosen. LÄS MER