scholarly journals The influence of the signal-to-noise ratio upon radio occultation inversion quality

2020 ◽  
Author(s):  
Michael Gorbunov
Keyword(s):  
White Noise ◽  
Radio Occultation ◽  
Signal To Noise Ratio ◽  
Observation Data ◽  
Signal To Noise ◽  
Weather Forecasts ◽  
Additive White Noise ◽  
Medium Range ◽  
Noise Ratio ◽  
Reference Fields

Abstract. In this paper, we investigate the influence of the signal-to-noise ratio (SNR) upon the radio occultation (RO) retrieval quality. We perform two series of numerical simulations: (1) with artificial RO data and, (2) with real COSMIC observations. We superimpose the simulated white noise with varying magnitudes upon both types of the observation data and evaluate the response in the statistics. The statistics use the reference fields of the analyses of European Centre for Medium-Range Weather Forecasts (ECMWF). Our simulations indicate that the effect of additive white noise has a threshold character: the influence of the noise is very low up to some threshold, but when the threshold is exceeded, the influence increases dramatically. Another conclusion is that, given RO observations of fair quality, the enhancement of the SNR cannot be expected to provide significant improvement in retrieval quality.

Effect of White Noise and Dichotomous Noise in a Bistable System

2011 ◽  
Vol 295-297 ◽  
pp. 2143-2146 ◽  
Author(s):  
Feng Guo ◽  
Xiao Feng Cheng ◽  
Xiao Dong Yuan ◽  
Shao Bo He
Keyword(s):  
White Noise ◽  
Adiabatic Approximation ◽  
Additive Noise ◽  
Signal To Noise Ratio ◽  
Bistable System ◽  
Signal To Noise ◽  
Dichotomous Noise ◽  
System Parameters ◽  
Additive White Noise ◽  
Asymmetric Dichotomous Noise

The stochastic resonance in a bistable system subject to asymmetric dichotomous noise and multiplicative and additive white noise is investigated. By using the properties of the dichotomous noise, under the adiabatic approximation condition, the expression of the signal-to-noise ratio (SNR) is obtained. It is found that the SNR is a non-monotonic function of the asymmetry of the dichotomous noise, and it varies non-monotonously with the intensities of the multiplicative and additive noise as well as with the system parameters. Moreover, the SNR depends on the correlation rate of the dichotomous noise.

scholarly journals Global Climatology of Equatorial Plasma Bubbles based on GPS Radio Occultation from FormoSat-3/COSMIC

2019 ◽  
Author(s):  
Ankur Kepkar ◽  
Christina Arras ◽  
Jens Wickert ◽  
Harald Schuh ◽  
Mahdi Alizadeh ◽  
...  
Keyword(s):  
Electron Density ◽  
Radio Occultation ◽  
Signal To Noise Ratio ◽  
Global Scale ◽  
Signal To Noise ◽  
Gps Radio Occultation ◽  
Plasma Bubbles ◽  
F Region ◽  
Equatorial Plasma Bubbles ◽  
Noise Ratio

Abstract. The emerging technique of GPS Radio Occultation has been used to detect the ionospheric irregularities prominent in the F-region known as equatorial plasma bubbles. The plasma bubbles are characterized by depreciated regions of electron density. For investigating the plasma bubbles, a nine-year (2008–2016) long time series of signal-to-noise ratio data are used from the vertical GPS radio occultation profiles. The variation in the signal-to-noise ratio of the GPS signals can be linked to vertical changes in the electron density profiles that mainly occur in line with the irregularities in the Earth's ionosphere. The analysis revealed that the F-region irregularities, associated with plasma bubbles occur mainly post sunset close to Earth's geomagnetic equator. Dependence on the solar cycle as well as distinctive seasonal variation is observed when analyzed for different years. In contrast to the other ionospheric remote sensing methods, GPS Radio Occultation technique uniquely personifies the activity of the plasma bubbles based on altitude resolution on a global scale.

STOCHASTIC RESONANCE ENHANCED BY WHITE NOISE IN A STOCHASTIC BISTABLE SYSTEM

2011 ◽  
Vol 25 (28) ◽  
pp. 3797-3804 ◽  
Author(s):  
GUO FENG ◽  
YU-RONG ZHOU ◽  
SHAO-FU LI
Keyword(s):  
White Noise ◽  
Stochastic Resonance ◽  
Additive Noise ◽  
Signal To Noise Ratio ◽  
Bistable System ◽  
Static Force ◽  
Noise Strength ◽  
Signal To Noise ◽  
System Parameters ◽  
Additive White Noise

The stochastic resonance (SR) for a stochastic bistable system driven by a static force and a periodic square-wave signal as well as by additive white noise is considered from the view of signal-to-noise ratio (SNR). It is found that the SNR appears SR behavior when it is plotted as a function of the additive noise strength or as a function of the system parameters. Moreover, the influence of the static force is opposite to that of the amplitude of the stochastic potential.

Stochastic Resonance in a Time-Delayed Logistic Growth Model Driven by Periodic Signal and White Noise

2011 ◽  
Vol 117-119 ◽  
pp. 703-707
Author(s):  
Yu Rong Zhou ◽  
Chong Qiu Fang
Keyword(s):  
White Noise ◽  
Stochastic Resonance ◽  
Growth Model ◽  
Delay Time ◽  
Signal To Noise Ratio ◽  
Logistic Growth ◽  
Periodic Signal ◽  
Signal To Noise ◽  
Logistic Growth Model ◽  
Noise Ratio

stochastic resonance; time-delayed Logistic growth model; signal-to-noise ratio Abstract. The stochastic resonance in a time-delayed Logistic growth model subject to correlated multiplicative and additive white noise as well as to multiplicative periodic signal is investigated. Using small time delay approximation, we get the expression of the signal-to-noise ratio (SNR). It is found that the SNR is a non-monotonic function of the system parameters, of the intensities of the multiplicative and additive noise, as well as of the correlation strength between the two noises. The effects of the delay time in the random force is in opposition to that of the delay time in the deterministic force.

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

Experiments in Bright-Field Imaging with Hollow-Cone Illumination

1981 ◽  
Vol 39 ◽  
pp. 226-227
Author(s):  
W. Kunath ◽  
K. Weiss ◽  
E. Zeitler
Keyword(s):  
Signal To Noise Ratio ◽  
Carbon Support ◽  
Electronic System ◽  
Optic Axis ◽  
Hollow Cone ◽  
Signal To Noise ◽  
Bright Field ◽  
Noise Ratio ◽  
Single Field ◽  
Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

Information capacity and bandwidth limitations in the SEM

1989 ◽  
Vol 47 ◽  
pp. 84-85
Author(s):  
D. C. Joy ◽  
R. D. Bunn
Keyword(s):  
Signal To Noise Ratio ◽  
Critical Dimension ◽  
Information Capacity ◽  
Acquisition Time ◽  
Signal To Noise ◽  
Sem Image ◽  
Probe Size ◽  
Minimum Number ◽  
Noise Ratio ◽  
Signal Channel

The information available from an SEM image is limited both by the inherent signal to noise ratio that characterizes the image and as a result of the transformations that it may undergo as it is passed through the amplifying circuits of the instrument. In applications such as Critical Dimension Metrology it is necessary to be able to quantify these limitations in order to be able to assess the likely precision of any measurement made with the microscope.The information capacity of an SEM signal, defined as the minimum number of bits needed to encode the output signal, depends on the signal to noise ratio of the image - which in turn depends on the probe size and source brightness and acquisition time per pixel - and on the efficiency of the specimen in producing the signal that is being observed. A detailed analysis of the secondary electron case shows that the information capacity C (bits/pixel) of the SEM signal channel could be written as :

Speech Reception in the Presence of Classroom Noise

1979 ◽  
Vol 10 (4) ◽  
pp. 221-230 ◽  
Author(s):  
Veronica Smyth
Keyword(s):  
Signal To Noise Ratio ◽  
Learning Processes ◽  
Speech Discrimination ◽  
Signal To Noise ◽  
Speech Reception ◽  
Monosyllabic Words ◽  
Noise Ratio

Three hundred children from five to 12 years of age were required to discriminate simple, familiar, monosyllabic words under two conditions: 1) quiet, and 2) in the presence of background classroom noise. Of the sample, 45.3% made errors in speech discrimination in the presence of background classroom noise. The effect was most marked in children younger than seven years six months. The results are discussed considering the signal-to-noise ratio and the possible effects of unwanted classroom noise on learning processes.

Sign in / Sign up

Export Citation Format

Share Document