Sökning: "Frequency Modulation"

Visar resultat 21 - 25 av 268 avhandlingar innehållade orden Frequency Modulation.

1. 21. Diode laser spectroscopy in extended wavelength ranges

   Författare :Ulf Gustafsson; Atomfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; diode-laser spectroscopy; frequency-modulation spectroscopy; frequency conversion; fluorescence spectroscopy; scattering; diffraction; Fysicumarkivet A:2000:Gustafsson; Atomic and molecular physics; Atom- och molekylärfysik; absorption spectroscopy;

   Sammanfattning : Diode laser spectroscopy performed in the ultraviolet, visible and infrared spectral regions is presented. The accessible wavelength range for visible and near-infrared diode lasers is extended by the use of sum- and difference-frequency generation. LÄS MER

3. 22. Environmental Monitoring - using diode-laser-based spectroscopic techniques

   Författare :Gabriel Somesfalean; Atomfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Diode-laser spectroscopy; frequency-modulation spectroscopy; frequency conversion; diffraction; scattering; Electromagnetism; acoustics; akustik; optik; absorption spectroscopy; Elektromagnetism; optics; Fysicumarkivet A:2004:Somesfalean;

   Sammanfattning : Monitoring of environmental gases is necessary to understand the complex processes governing global warming and the impact of pollutant emissions related to human activity. Diode-laser-based spectroscopic techniques, being robust and affordable, have a great potential to become an industrially well-established technology for environmental sensing. LÄS MER

4. 23. Multi-Gigabaud Millimeter-Wave Communication - Challenges and Solutions

   Författare :Jingjing Chen; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; phase noise; high-order modulation; 5G; multi-gigabaud; PAM-4; high data rate; white noise; multi-gigabit; phase noise mitigation; 64-QAM; mobile backhaul; VCSEL driver; Frequency multiplier; modem; high frequency oscillator; multiplicative noise; power detector; fronthaul; millimeter-wave communication;

   Sammanfattning : A major challenge in future mobile networks is to overcome the capacity barrier in wireless communication. Utilizing large bandwidth at higher frequencies is key to enabling capacity upgrade for next generation mobile networks (5G). LÄS MER

5. 24. Optical Frequency Comb Fourier Transform Spectroscopy

   Författare :Alexandra C. Johansson; Aleksandra Foltynowicz; Ove Axner; Jürgen Röpcke; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Optical frequency comb spectroscopy; Fourier transform; molecular absorption dispersion; fysik; Physics;

   Sammanfattning : Fourier transform spectroscopy (FTS) based on optical frequency combs is an excellent spectroscopic tool as it provides broadband molecular spectra with high spectral resolution and an absolutely calibrated frequency scale. Moreover, the equidistant comb mode structure enables efficient coupling of the comb to enhancement cavities, yielding high detection sensitivity. LÄS MER

7. 25. Multirate Codes and Multicarrier Modulation for Future Communication Systems

   Författare :Pål Frenger; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; channel estimation; code-spread CDMA; DS-CDMA; convolutional codes; interference cancellation; nested convolutional codes; multicarrier modulation; optimum distance spectrum ODS ; rate-compatible punctured convolutional codes RCPC-codes ; OFDM; turbo decoding; rate matching; parallel combinatory signaling; Rayleigh fading;

   Sammanfattning : In this thesis, new detection and modulation methods for multicarrier systems are presented. The proposed multicarrier detectors are based on feedback of previously detected symbols and the idea is to exploit the correlation, both in time between consecutive symbols, and in frequency between neighboring sub-carriers. LÄS MER