Validation of theα-μModel of the Power Spectral Density of GPS Ionospheric Amplitude Scintillation

Theα-μmodel has become widely used in statistical analyses of radio channels, due to the flexibility provided by its two degrees of freedom. Among several applications, it has been used in the characterization of low-latitude amplitude scintillation, which frequently occurs during the nighttime of particular seasons of high solar flux years, affecting radio signals that propagate through the ionosphere. Depending on temporal and spatial distributions, ionospheric scintillation may cause availability and precision problems to users of global navigation satellite systems. The present work initially stresses the importance of the flexibility provided byα-μmodel in comparison with the limitations of a single-parameter distribution for the representation of first-order statistics of amplitude scintillation. Next, it focuses on the statistical evaluation of the power spectral density of ionospheric amplitude scintillation. The formulation based on theα-μmodel is developed and validated using experimental data obtained in São José dos Campos (23.1°S; 45.8°W; dip latitude 17.3°S), Brazil, located near the southern crest of the ionospheric equatorial ionization anomaly. These data were collected between December 2001 and January 2002, a period of high solar flux conditions. The results show that the proposed model fits power spectral densities estimated from field data quite well.

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Evaluation of power spectral density of passive intermodulation distortion in high-power communication satellite systems

Journal of Electronics (China) ◽

10.1007/bf02688145 ◽

2005 ◽

Vol 22 (2) ◽

pp. 181-184 ◽

Cited By ~ 1

Author(s):

Shiquan Zhang ◽

Debiao Ge

Keyword(s):

Spectral Density ◽

Power Spectral Density ◽

High Power ◽

Intermodulation Distortion ◽

Satellite Systems ◽

Communication Satellite ◽

Power Spectral ◽

Passive Intermodulation

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Role of the external drivers in the occurrence of low-latitude ionospheric scintillation revealed by multi-scale analysis

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2019032 ◽

2019 ◽

Vol 9 ◽

pp. A35 ◽

Cited By ~ 4

Author(s):

Luca Spogli ◽

Mirko Piersanti ◽

Claudio Cesaroni ◽

Massimo Materassi ◽

Antonio Cicone ◽

...

Keyword(s):

Global Navigation Satellite Systems ◽

Scintillation Index ◽

Ionospheric Scintillation ◽

Satellite Systems ◽

Multi Scale ◽

Amplitude Scintillation ◽

Frequency Components ◽

Scale Properties ◽

Iterative Filtering ◽

Global Navigation Satellite

We analyze the amplitude scintillation on L-band signals over San Miguel de Tucumán (Argentina), focusing on the multi-scale variability and speculating on the possible relationship between forcing factors from the geospace and the ionospheric response. The site is nominally located below the expected position of the southern crest of the Equatorial Ionospheric Anomaly (EIA). For this scope, we concentrate on the period 1–31 March 2011, during which one minor and one moderate storm characterize the first half of the month, while generally quiet conditions of the geospace stand for the second half. By leveraging on the Adaptive Local Iterative Filtering (ALIF) signal decomposition technique, we investigate the multi-scale properties of Global Navigation Satellite Systems (GNSS) amplitude scintillation and helio-geophysical parameters, looking for possible cause-effect mechanisms relating the former to the latter. Namely, we identify resonant modes in the Akasofu (ε) parameter as likely related to the frequency components in the time evolution found for the amplitude scintillation index, hence modulating the scintillation itself.

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Calculation of Evolutionary Power Spectral Density of Bridge Response to Earthquakes by Convolution Summation

International Journal of Structural Stability and Dynamics ◽

10.1142/s021945541950041x ◽

2019 ◽

Vol 19 (04) ◽

pp. 1950041

Author(s):

Xianting Du ◽

Hong Qiao ◽

Chaoyi Xia ◽

He Xia

Keyword(s):

Spectral Density ◽

Power Spectral Density ◽

Degrees Of Freedom ◽

Computational Cost ◽

Time History ◽

Dynamic Component ◽

Rigid Frame ◽

Power Spectral ◽

History Analysis ◽

Constant Coefficients

This paper presents a method for calculating the evolutionary power spectral density (EPSD) of the seismic response of bridges using the convolution summation. With zero initial values, a formula for the dynamic component of the response of bridges to spatially varying seismic ground motions is derived as the convolution summation, by assuming the seismic acceleration to vary linearly between two adjacent time stations. The convolution summation is used for calculating the convolution integral of the dynamic component response factor in the EPSD, in which the constant coefficients are independent of the harmonically modulated excitation. The constant coefficients are obtained by the time-history analysis using triangular unit impulse acceleration excitations. The computational cost of the EPSD depends mainly on the amount of degrees-of-freedom (DOFs) numbers of bridge supports in contact. The corresponding computational scheme is proposed, and its validity is indirectly verified with a single DOF system, by comparing the results obtained with those of the existing methods. Finally, a three-span continuous rigid-frame bridge is taken as a case study to illustrate the applicability and effectiveness of the proposed scheme.

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