Time-frequency distribution - a review
Article Abstract:
The goals of the field of time-varying distributions is to determine how the spectral content of signals change in time and the meaning of the spectrum and its transitions. This overview and tutorial on time-varying distributions describes the history of its concepts and such distributions and methods for deriving them as Wigner, Riharczek, Page, Choi-Williams, Ville-Moyal, and a unified approach. Other technologies for deriving and analyzing the spectra include energy density spectrograms, time-frequency filtering and synthesis, the use of Hilbert transforms to calculate instantaneous frequency, and concepts of quantum mechanics and the uncertainty principle. Time-varying distribution study is applicable to almost any situation where non-stationary signals exist. Underlying equations and unresolved issues are also described.
Publication Name: Proceedings of the IEEE
Subject: Electronics
ISSN: 0018-9219
Year: 1989
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Fiber-optic sensors for continuous clinical monitoring
Article Abstract:
Optical sensors offer great promise as continuous clinical monitoring systems. Without posing an electrical hazard to the patient, optical sensors offer the potential for drift-free systems. However, optical sensors cannot be used in clinical medicine until problems of sterilization, calibration and blood compatibility are solved. Recent advances in optoelectronics have dramatically simplified the instrumentation necessary for supporting optical sensors. The sensors are prepared by attaching an indicating layer to an optical fiber's distal tip. Light sent down the optical fiber is modulated by the indicating layer. The returned light's degree of modulation is a gauge of the amount of a particular chemical species in contact with the fiber tip.
Publication Name: Proceedings of the IEEE
Subject: Electronics
ISSN: 0018-9219
Year: 1992
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