scholarly journals Spaced-Antenna Interferometry to Detect and Locate Subvolume Inhomogeneities of Reflectivity: An Analogy with Monopulse Radar

2008 ◽  
Vol 25 (11) ◽  
pp. 1921-1938 ◽  
Author(s):  
Guifu Zhang ◽  
Richard J. Doviak
Keyword(s):  
Correlation Function ◽  
Power Spectrum ◽  
Correlation Coefficient ◽  
Wave Scattering ◽  
Cross Correlation ◽  
Phased Array ◽  
Weather Radar ◽  
Individual Object ◽  
Potential Applications ◽  
Nonuniform Beam

Abstract The theory of spaced-antenna interferometry (SAI) is formulated to detect and locate deterministic objects and reflectivity inhomogeneities embedded within the phased-array weather radar’s resolution volume V6 and to improve weather radar performance. An analogy is made between monopulse tracking and SAI. The cross-correlation function and its power spectrum are derived based on wave scattering by a large deterministic object and clusters of randomly distributed precipitation particles. It is shown that nonuniform beam filling leads to an effective narrower beam and an increase in cross-correlation coefficient at zero lag. Hence, an individual object or a subvolume inhomogeneity can be detected and located by SAI. This capability further enhances the potential applications of phased-array weather radar used as a multimission system.

The Impact of Beam Broadening on the Quality of Radar Polarimetric Data

2007 ◽  
Vol 24 (5) ◽  
pp. 729-744 ◽  
Author(s):  
Alexander V. Ryzhkov
Keyword(s):  
Correlation Coefficient ◽  
Cross Correlation ◽  
Horizontal Gradients ◽  
Analytical Formulas ◽  
Radar Resolution ◽  
Differential Reflectivity ◽  
The Impact ◽  
Nonuniform Beam ◽  
Beam Broadening

Abstract The impact of beam broadening on the quality of radar polarimetric data in the presence of nonuniform beam filling (NBF) is examined both theoretically and experimentally. Cross-beam gradients of radar reflectivity Z, differential reflectivity ZDR, and differential phase ΦDP within the radar resolution volume may produce significant biases of ZDR, ΦDP, and the cross-correlation coefficient ρhv. These biases increase with range as a result of progressive broadening of the radar beam. They are also larger at shorter radar wavelengths and wider antenna beams. Simple analytical formulas are suggested for estimating the NBF-induced biases from the measured vertical and horizontal gradients of Z, ZDR, and ΦDP. Analysis of polarimetric data collected by the KOUN Weather Surveillance Radar-1988 Doppler (WSR-88D) demonstrates that frequently observed perturbations of the radial ΦDP profiles and radially oriented “valleys” of ρhv depression can be qualitatively and quantitatively explained using the suggested NBF model.

scholarly journals TECHNOLOGIES FOR CALCULATING THE CORRELATION COEFFICIENT BETWEEN THE USEFUL SIGNAL AND THE NOISE USING THE ESTIMATE OF THEIR RELAY CROSS-CORRELATION FUNCTION

2021 ◽  
Vol 5 ◽  
pp. 93-103
Author(s):  
Telman Aliev ◽  
◽  
Nailya Musaeva ◽  
◽  
Keyword(s):  
Correlation Function ◽  
Correlation Analysis ◽  
Correlation Coefficient ◽  
Cross Correlation ◽  
Technical Condition ◽  
Cross Correlation Function ◽  
Noisy Signal ◽  
Normalized Cross Correlation ◽  
Useful Signal ◽  
Noisy Signals

It is shown that when noisy signals are formed, the condition for the absence of correlation between the useful signal and the noise is often violated. This causes certain errors of correlation analysis of these signals, resulting in the inadequacy of the results obtained. In addition, the existing correlation analysis technologies do not allow using the noise as a carrier of valuable information. Therefore, the full use of the colossal information potential of noisy signals requires new technologies that would exclude the loss of valuable information, both when the known classical conditions are met and when they are not. Algorithms are developed for determining the estimate of the correlation coefficient between the useful signal and the noise, which cannot be measured directly or isolated from a noisy signal. For this purpose, the normalized cross-correlation function between the useful signal and the noise is used. An algorithm for calculating the estimates of the normalized cross-correlation function between the useful signal and the noise is developed using the estimates of the relay correlation function of the noisy signal. It is shown that the value of this estimate, calculated at a zero time shift, is an estimate of the correlation coefficient between the useful signal and the noise. A technology for conducting computational experiments is proposed, a comparative analysis is carried out, and the reliability of the proposed algorithms and technologies is confirmed. It is shown that under the normal technical condition of the object, the estimates of the relay cross-correlation function and the correlation coefficient between the useful signal and the noise will be close to zero. With the emergence of various defects preceding malfunctions at the object, these estimates will change depending on the degree of damage. Therefore, it is the estimates of the cross-correlation function and the correlation coefficient between the useful signal and the noise that should be used in monitoring and control systems as informative attributes for signaling and monitoring the beginning of changes in the technical condition of objects and the dynamics of their malfunctions. The use of these new effective informative attributes makes it possible to increase the degree of accuracy and reliability of operation of modern information systems.

Quantitative Comparison of Cylindricity Profiles Measured with Different Methods Using Legendre-Fourier Coefficients

2010 ◽  
Vol 17 (3) ◽  
pp. 397-403 ◽  
Author(s):  
Stanisław Adamczak ◽  
Dariusz Janecki ◽  
Włodzimierz Makieła ◽  
Krzysztof Stępień
Keyword(s):  
Correlation Function ◽  
Correlation Coefficient ◽  
Cross Correlation ◽  
Fourier Coefficients ◽  
Measurement Data ◽  
Fourier Method ◽  
Quantitative Comparison ◽  
Cross Correlation Function ◽  
Measuring Instrument ◽  
Coefficient Of Correlation

Quantitative Comparison of Cylindricity Profiles Measured with Different Methods Using Legendre-Fourier CoefficientsThe paper discusses a method of quantitative comparison of cylindricity profiles measured with different strategies. The method is based on applying so-called Legendre-Fourier coefficients. The comparison is carried out by computing the correlation coefficient between the profiles. It is conducted by applying a normalized cross-correlation function and it requires approximation of cylindrical surfaces using the Legendre-Fourier method. As the example two sets of measurement data are employed: the first from the CMM and the second one from the traditional radial measuring instrument. The measuring data are compared by analyzing the values of selected cylindricity parameters and calculating the coefficient of correlation between profiles.

scholarly journals First Evidence of Intrinsic Alignments of Red Galaxies at z > 1: Cross Correlation between CFHTLenS and FastSound Samples

2021 ◽  
Vol 924 (1) ◽  
pp. L3
Author(s):  
Motonari Tonegawa ◽  
Teppei Okumura
Keyword(s):  
Correlation Function ◽  
Power Spectrum ◽  
Survey Data ◽  
Cross Correlation ◽  
Cross Correlation Function ◽  
Weak Lensing ◽  
Galaxy Clustering ◽  
Alignment Model ◽  
Red Galaxies ◽  
Marginal Detection

Abstract We report the first evidence for intrinsic alignment (IA) of red galaxies at z > 1. We measure the gravitational shear-intrinsic ellipticity cross correlation function at z ∼ 1.3 using galaxy positions from the FastSound spectroscopic survey and galaxy shapes from the Canada France Hawaii telescope lensing survey data. Adopting the nonlinear alignment model, we obtain a 2.4σ level detection of the IA amplitude A LA = 27.48 − 11.54 + 11.53 (and 2.6σ with A LA = 29.43 − 11.49 + 11.48 when weak lensing contaminations are taken into account), which is larger than the value extrapolated from the constraints obtained at lower redshifts. Our measured IA is translated into a ∼20% contamination of the weak-lensing power spectrum for the red galaxies. This marginal detection of IA for red galaxies at z > 1 motivates the continuing investigation of the nature of IA for weak lensing studies. Furthermore, our result provides the first step to utilize IA measurements in future high-z surveys as a cosmological probe, complementary to galaxy clustering and lensing.

The Evaluation on the Observation Accuracy of Phased Array Weather Radar

2014 ◽  
Vol 134 (4) ◽  
pp. 204-210 ◽  
Author(s):  
Yuki Hirano ◽  
Kouichi Maruo ◽  
Shigeharu Shimamura ◽  
Satoru Yoshida ◽  
Tomoo Ushio ◽  
...  
Keyword(s):  
Phased Array ◽  
Weather Radar

scholarly journals Detrended Multiple Cross-Correlation Coefficient applied to solar radiation, air temperature and relative humidity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Andrea de Almeida Brito ◽  
Heráclio Alves de Araújo ◽  
Gilney Figueira Zebende
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Solar Energy ◽  
Correlation Coefficient ◽  
Air Temperature ◽  
Cross Correlation ◽  
Global Solar Radiation ◽  
Meteorological Variables ◽  
Hourly Data ◽  
Cross Correlations

AbstractDue to the importance of generating energy sustainably, with the Sun being a large solar power plant for the Earth, we study the cross-correlations between the main meteorological variables (global solar radiation, air temperature, and relative air humidity) from a global cross-correlation perspective to efficiently capture solar energy. This is done initially between pairs of these variables, with the Detrended Cross-Correlation Coefficient, ρDCCA, and subsequently with the recently developed Multiple Detrended Cross-Correlation Coefficient, $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2. We use the hourly data from three meteorological stations of the Brazilian Institute of Meteorology located in the state of Bahia (Brazil). Initially, with the original data, we set up a color map for each variable to show the time dynamics. After, ρDCCA was calculated, thus obtaining a positive value between the global solar radiation and air temperature, and a negative value between the global solar radiation and air relative humidity, for all time scales. Finally, for the first time, was applied $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2 to analyze cross-correlations between three meteorological variables at the same time. On taking the global radiation as the dependent variable, and assuming that $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}={\bf{1}}$$DMCx2=1 (which varies from 0 to 1) is the ideal value for the capture of solar energy, our analysis finds some patterns (differences) involving these meteorological stations with a high intensity of annual solar radiation.

scholarly journals An Estimator for Weather Radar Doppler Power Spectrum via Minimum Mean Square Error

2021 ◽  
pp. 1-16
Author(s):  
Eiichi Yoshikawa ◽  
Naoya Takizawa ◽  
Hiroshi Kikuchi ◽  
Tomoaki Mega ◽  
Tomoo Ushio
Keyword(s):  
Power Spectrum ◽  
Mean Square Error ◽  
Minimum Mean Square Error ◽  
Weather Radar ◽  
Mean Square ◽  
Doppler Power
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