scholarly journals On the determination of the atmospheric outer scale length of turbulence using GPS phase difference observations: the Seewinkel network

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Gaël Kermarrec ◽  
Steffen Schön
Keyword(s):  
Power Spectrum ◽  
Phase Difference ◽  
Low Frequency ◽  
Satellite System ◽  
Position Estimation ◽  
Frequency Noise ◽  
Outer Scale ◽  
Phase Measurements ◽  
The Impact ◽  
Scale Length

AbstractMicrowave electromagnetic signals from the Global Navigation Satellite System (GNSS) are affected by their travel through the atmosphere: the troposphere, a non-dispersive medium, has an especial impact on the measurements. The long-term variations of the tropospheric refractive index delay the signals, whereas its random variations correlate with the phase measurements. The correlation structure of residuals from GNSS relative position estimation provides a unique opportunity to study specific properties of the turbulent atmosphere. Prior to such a study, the residuals have to be filtered from unwanted additional effects, such as multipath. In this contribution, we propose to investigate the property of the atmospheric noise by using a new methodology combining the empirical mode decomposition with the Hilbert–Huang transform. The chirurgical “designalling of the noise” aims to filter both the white noise and low-frequency noise to extract only the noise coming from tropospheric turbulence. Further analysis of the power spectrum of phase difference can be performed, including the study of the cut-off frequencies and the two slopes of the power spectrum of phase differences. The obtained values can be compared with theoretical expectations. In this contribution, we use Global Positioning System (GPS) phase observations from the Seewinkel network, specially designed to study the impact of atmospheric turbulence on GPS phase observations. We show that (i) a two-slope power spectrum can be found in the residuals and (ii) that the outer scale length can be taken to a constant value, close to the physically expected one and in relation with the size of the eddies at tropospheric height.

Ceiling Construction Low-Frequency Noise Issues

2013 ◽  
Vol 649 ◽  
pp. 277-280
Author(s):  
Petra Berková ◽  
Pavel Berka
Keyword(s):  
Spectral Analysis ◽  
Low Frequency ◽  
Sound Insulation ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Frequency Tone ◽  
The Impact ◽  
40 Hz

Through the use of a spectral analysis of the source of noise – person’s movement over the ceiling construction – it was found out that in this kind of noise distinctive low-frequency tone components occur (31,5 - 40 Hz) which is beyond the evaluation area of the impact sound insulation of the ceiling construction, s. [2], [3].

scholarly journals Making maps of cosmic microwave background polarization for B-mode studies: the POLARBEAR example

2017 ◽  
Vol 600 ◽  
pp. A60 ◽  
Author(s):  
Davide Poletti ◽  
Giulio Fabbian ◽  
Maude Le Jeune ◽  
Julien Peloton ◽  
Kam Arnold ◽  
...  
Keyword(s):  
Cosmic Microwave Background ◽  
Time Domain ◽  
Power Spectra ◽  
Low Frequency ◽  
Frequency Noise ◽  
Spectrum Estimation ◽  
Microwave Background ◽  
Polarization Studies ◽  
Ordered Data ◽  
The Impact

Analysis of cosmic microwave background (CMB) datasets typically requires some filtering of the raw time-ordered data. For instance, in the context of ground-based observations, filtering is frequently used to minimize the impact of low frequency noise, atmospheric contributions and/or scan synchronous signals on the resulting maps. In this work we have explicitly constructed a general filtering operator, which can unambiguously remove any set of unwanted modes in the data, and then amend the map-making procedure in order to incorporate and correct for it. We show that such an approach is mathematically equivalent to the solution of a problem in which the sky signal and unwanted modes are estimated simultaneously and the latter are marginalized over. We investigated the conditions under which this amended map-making procedure can render an unbiased estimate of the sky signal in realistic circumstances. We then discuss the potential implications of these observations on the choice of map-making and power spectrum estimation approaches in the context of B-mode polarization studies. Specifically, we have studied the effects of time-domain filtering on the noise correlation structure in the map domain, as well as impact it may haveon the performance of the popular pseudo-spectrum estimators. We conclude that although maps produced by the proposed estimators arguably provide the most faithful representation of the sky possible given the data, they may not straightforwardly lead to the best constraints on the power spectra of the underlying sky signal and special care may need to be taken to ensure this is the case. By contrast, simplified map-makers which do not explicitly correct for time-domain filtering, but leave it to subsequent steps in the data analysis, may perform equally well and be easier and faster to implement. We focused on polarization-sensitive measurements targeting the B-mode component of the CMB signal and apply the proposed methods to realistic simulations based on characteristics of an actual CMB polarization experiment, POLARBEAR. Our analysis and conclusions are however more generally applicable.

scholarly journals In Design of an Ocean Bottom Seismometer Sensor: Minimize Vibration Experienced by Underwater Low-Frequency Noise

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3446 ◽  
Author(s):  
Xiaohan Wang ◽  
Shangchun Piao ◽  
Yahui Lei ◽  
Nansong Li
Keyword(s):  
Seismic Waves ◽  
Low Frequency ◽  
Sound Field ◽  
Average Density ◽  
Vibration Velocity ◽  
Frequency Noise ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Underwater Noise ◽  
The Impact

Ocean Bottom Seismometers (OBS) placed on the seafloor surface are utilized for measuring the ocean bottom seismic waves. The vibration of OBS excited by underwater noise on its surface may interfere with its measured results of seismic waves. In this particular study, an OBS was placed on the seabed, while ray acoustic theory was used to deduce the sound field distribution around the OBS. Then using this information, the analytical expression for the OBS vibration velocity was obtained in order to find various factors affecting its amplitude. The finite element computing software COMSOL Multiphysics® (COMSOL) was used to obtain the vibration response model of the OBS which was exposed to underwater noise. The vibration velocity for the OBS calculated by COMSOL agreed with the theoretical result. Moreover, the vibration velocity of OBS with different densities, shapes, and characters were investigated as well. An OBS with hemispherical shape, consistent average density as that of the seafloor, and a physical structure of double tank has displayed minimum amplitude of vibration velocity. The proposed COMSOL model predicted the impact of underwater noise while detecting the ocean bottom seismic waves with the OBS. In addition, it provides significant help for the design and optimization of an appropriate OBS.

Low-frequency noise and static analysis of the impact of the TiN metal gate thicknesses on n- and p-channel MuGFETs

2010 ◽  
Vol 54 (12) ◽  
pp. 1592-1597 ◽  
Author(s):  
M. Rodrigues ◽  
J.A. Martino ◽  
A. Mercha ◽  
N. Collaert ◽  
E. Simoen ◽  
...  
Keyword(s):  
Static Analysis ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Metal Gate ◽  
Tin Metal ◽  
The Impact

Low Frequency Noise Analysis in Advanced CMOS Devices

2011 ◽  
Vol 324 ◽  
pp. 441-444 ◽  
Author(s):  
Jalal Jomaah ◽  
Majida Fadlallah ◽  
Gerard Ghibaudo
Keyword(s):  
Experimental Data ◽  
Noise Analysis ◽  
Low Frequency ◽  
Deep Submicron ◽  
Electrical Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Sources ◽  
The Impact ◽  
Mobility Fluctuations

A review of recent results concerning the low frequency noise in modern CMOS devices is given. The approaches such as the carrier number and the Hooge mobility fluctuations used for the analysis of the noise sources are illustrated through experimental data obtained on advanced CMOS generations. Furthermore, the impact on the electrical noise of the shrinking of CMOS devices in the deep submicron range is also shown.

scholarly journals Low Frequency Noise in Tantalum Capacitors

1987 ◽  
Vol 12 (4) ◽  
pp. 215-221 ◽  
Author(s):  
D. T. Smith
Keyword(s):  
Power Spectrum ◽  
Bias Voltage ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Current

Noise has been measured in a number of biased solid tantalum capacitors at frequencies down to 0.01 Hz. The noise current was found to have a 1/f power spectrum, and the amplitude varied with the bias voltage with a law in the range 1st to 4th power. There was a large difference in amplitudes between different capacitors of the same type.

The impact of active layer thickness on low-frequency noise characteristics in InZnO thin-film transistors with high mobility

2012 ◽  
Vol 100 (17) ◽  
pp. 173501 ◽  
Author(s):  
Hyun-Sik Choi ◽  
Sanghun Jeon ◽  
Hojung Kim ◽  
Jaikwang Shin ◽  
Changjung Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Layer Thickness ◽  
Active Layer ◽  
Thin Film Transistors ◽  
Low Frequency ◽  
High Mobility ◽  
Active Layer Thickness ◽  
Frequency Noise ◽  
Noise Characteristics ◽  
The Impact
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