MIDIT OFD CATS Modelling, Nonlinear Dynamics Optics and Fluid Dynamics Chaos and Turbulence Studies and Irreversible Thermodynamics Risø National Laboratory Niels Bohr Institute and Technical University of Denmark Building 128 Department of Chemistry Building 321 P.O. Box 49 University of Copenhagen DK-2800 Lyngby DK-4000 Roskilde DK-2100 Copenhagen Ø Denmark Denmark Denmark
by Andrey L. Pankratov
Department of Physical Sciences
University of Salerno, Italy
Thursday April 27, 2000, 14.00 h
at MIDIT, IMM, Bldg. 305, Room 018, DTU,
The determination of the spectral form of the oscillator
signal may be considered in certain cases as the final goal of
investigation of influence of random forces on an oscillator. The
existence of a continuous part of the spectrum, even when it
contains a quasi-monochromatic line, may restrict, e.g.,
the detection of small signals located close to the oscillator frequency.
The necessity of a relatively exact knowledge of the spectrum
is obvious in this case.
On the other hand, in a number of physical tasks the mechanism of broadening of the spectral line is considered on the basis of a random frequency modulation. Therefore, the determination of the spectral form of a signal with fluctuations in both amplitude and frequency is of independent importance.
A unified method for finding the shape and the linewidth of the signal, in general having correlated amplitude and frequency fluctuations, will be considered. The analysis is performed both for stationary and nonstationary fluctuations in amplitude and frequency. The frequency fluctuations will be considered in detail and the influence of correlated amplitude and frequency fluctuations on the form of spectral line will be described.