Power measurement in digital wireless communication systems often suffers from poor repeatability, usually accompanied by a low accuracy. To face the problem, the use of parametric spectral ...estimators is investigated in this paper. In particular, a new method is proposed, which first estimates the power spectral density (PSD) of the analyzed signal through Burg's solution, and then evaluates the power by applying straightforward measurement algorithms to the estimated PSD. The results of a number of experiments, carried out on both laboratory and actual signals peculiar to digital wireless communication systems, assess the efficacy and reliability of the method. Moreover, a comparison of the achieved performance to that offered by an alternative measurement solution, already proposed by the authors and based on nonparametric PSD estimation, shows that the method allows for a significant reduction of measurement time, while exhibiting the same repeatability.
Links between electroencephalograms (EEGs) and underlying aspects of neurophysiology and anatomy are poorly understood. Here a nonlinear continuum model of large-scale brain electrical activity is ...used to analyze arousal states and their stability and nonlinear dynamics for physiologically realistic parameters. A simple ordered arousal sequence in a reduced parameter space is inferred and found to be consistent with experimentally determined parameters of waking states. Instabilities arise at spectral peaks of the major clinically observed EEG rhythms-mainly slow wave, delta, theta, alpha, and sleep spindle-with each instability zone lying near its most common experimental precursor arousal states in the reduced space. Theta, alpha, and spindle instabilities evolve toward low-dimensional nonlinear limit cycles that correspond closely to EEGs of petit mal seizures for theta instability, and grand mal seizures for the other types. Nonlinear stimulus-induced entrainment and seizures are also seen, EEG spectra and potentials evoked by stimuli are reproduced, and numerous other points of experimental agreement are found. Inverse modeling enables physiological parameters underlying observed EEGs to be determined by a new, noninvasive route. This model thus provides a single, powerful framework for quantitative understanding of a wide variety of brain phenomena.
This paper describes outline of the piggy-back satellite "INDEX" for demonstration of advanced satellite technologies as well as for observation of fine structure of aurora. Aurora observation will ...be carried out by three cameras(MAC) with a monochromatic UV filter. Electron and ion spectrum analyzer (ESA/ISA) will measure the particle phenomena together with the aurora hanging. INDEX satellite will be launched in 2002 by Japanese H2-A. The satellite is mainly controlled by the high-speed, fault-tolerant on-board RICS processor (three-voting system of SH-3). The attitude control is a compact system of three-axis stabilization. Although the size of INDEX is small (50Kg class), several newly-developed technologies are applied to the satellite system, including silicon-on-insulator devices, variable emittance radiator, solar-concentrated paddles, lithium-ion battery, and GPS receiver with all-sky antenna-coverage. copyright 2001 International Astronautical Federation. Published by Elsevier Science Lt d.
The extension of the photon correlation spectroscopy (PCS) in multiple scattering regime, so-called diffusing wave spectroscopy (DWS) was employed to the study of blood samples. Multiple scattered ...light from a helium–neon (He–Ne) laser beam incident on the blood samples was detected by a photomultiplier, and both the temporal autocorrelation intensity functions
g
2(
τ) and power spectra
S(
ω) were measured by a spectrum analyzer. The potentials of using DWS for the qualitative and quantitative determination of the structural characteristics of the blood elements were studied experimentally. The experimental studies made, permits the use of DWS for blood cells monitoring in a multiple scattering regime. This paper describes our initial attempts at applying DWS to the study of the discrete blood samples of both healthy donors and patients with the cardiac ischemia. The subsequent experiments provide a verification of DWS of blood cells shape monitoring under multiple scattering.
This chapter is concerned with machine implementation of transform techniques, either software or hardware, to obtain data in a form convenient for ac impedance analysis. It describes the advantages ...and limitations conferred by the use of phase‐sensitive detector (PSD). In addition, dynamic spectrum analyzers are capable of measuring amplitude and phase accurately; these are basically time‐domain instruments, and their function is discussed. The chapter discusses the successive‐approximation and integration analog to‐digital converters (ADCs) in detail. It presents ideas and techniques that are applied in the latest generation of commercially available equipment to the impedance measurement of many types of cells/samples including conductors at one extreme and dielectric/insulator materials at the other. The chapter examines single sine and multi‐sine techniques in more detail, and assesses the advantages/disadvantages of each technique.
A compact self-seeded pulsed tunable laser is described. Its optical cavity comprises a diffraction grating, operating at a grazing angle of incidence as a spectral selector and narrow-band spectral ...gate. The grating couples two partially overlapping laser channels: a highly selective master laser and a nonselective slave laser. Due to the implemented efficient intracavity self-seeding the laser emits spectrally pure single-longitudinal-mode radiation at two independently tunable wavelengths, with an efficiency and output energy that are typical for nonselective lasers. Results of the experimental investigation of the laser's output characteristics are presented.
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