Radar Resolution

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Yunhan Dong - One of the best experts on this subject based on the ideXlab platform.

  • modelling x band sea clutter with the k distribution shape parameter variation
    International Radar Conference, 2009
    Co-Authors: David J. Crisp, Luke Rosenberg, N J S Stacy, Yunhan Dong
    Abstract:

    Performance modelling techniques for maritime Radar target detection problems typically make use of a parametric probability distribution for the background ocean backscatter. In this paper, measured X-band sea clutter is analysed by fitting a K-distribution and the variation of its parameters with Radar Resolution, polarisation, viewing grazing and azimuth angles and ocean wind and wave conditions is examined. Grazing angles lie in the range 10° to 45°. Earlier work has already characterised the variation in the mean of the distribution. Here, the shape parameter υ is studied. Surprisingly, it is found that υ exhibits a sinusoidal like variation with azimuth angle which is aligned with the direction of the wind waves rather than the swell.

  • Modelling X-band sea clutter with the K-distribution: Shape parameter variation
    2009
    Co-Authors: David J. Crisp, Luke Rosenberg, N J S Stacy, Yunhan Dong
    Abstract:

    Performance modelling techniques for maritime Radar target detection problems typically make use of a parametric probability distribution for the background ocean backscatter. In this paper, measured X-band sea clutter is analysed by fitting a K-distribution and the variation of its parameters with Radar Resolution, polarisation, viewing grazing and azimuth angles and ocean wind and wave conditions is examined. Grazing angles lie in the range 10° to 45°. Earlier work has already characterised the variation in the mean of the distribution. Here, the shape parameter υ is studied. Surprisingly, it is found that υ exhibits a sinusoidal like variation with azimuth angle which is aligned with the direction of the wind waves rather than the swell.

  • clutter spatial distribution and new approaches of parameter estimation for weibull and k distributions
    2004
    Co-Authors: Yunhan Dong
    Abstract:

    Abstract : The spatial distribution of surface clutter in general depends on Radar Resolution, grazing angle and scatterers on the surface. The Weibull, K- and lognormal distributions are commonly used to approximate the clutter spatial distribution. Comparisons among all three distributions are reviewed and extended. Statistical properties of the Weibull and K- distributions in the log domain are derived and then used in new approaches, named as unbiased estimation schemes, for faster parameter estimation for the Weibull and K- distributions. The maximum likelihood estimates for the K-distribution are also derived without the need of the derivative of the Bessel function. The proposed unbiased estimation schemes provide nearly as identical estimates as the maximum likelihood scheme does, according to real aperture Radar data and synthetic aperture Radar data analysed.

Mark Yeary - One of the best experts on this subject based on the ideXlab platform.

  • ICASSP (2) - Spectral Analysis of Polarimetric Weather Radar Data with Multiple Processes in a Resolution Volume
    2007 IEEE International Conference on Acoustics Speech and Signal Processing - ICASSP '07, 2007
    Co-Authors: Svetlana Bachmann, Victor Debrunner, Dusan S. Zrnic, Mark Yeary
    Abstract:

    A new approach for the clear air velocity estimation in weather Radar is presented. A combination of nonparametric with parametric spectral analysis allows us to identify and extract multiple processes caused by different scatterer types within a single Radar Resolution volume. An example of clear air observed using an S-band dual polarization Radar is presented. Heretofore, migrating birds and wind-blown insects that are mixed within each Resolution volume caused such data to be unusable for meteorological interpretation. In this paper, we construct power spectral densities of polarimetric variables. We use the polarimetric spectral densities to differentiate the scatterer types within the observed Radar Resolution volume. We demonstrate how our combination of non-parametric and parametric spectral analysis can be used to retrieve the true wind velocity in situations with severe contamination by biological scatterers.

Alexander Yarovoy - One of the best experts on this subject based on the ideXlab platform.

  • Assessment of the rain drop inertia effect for Radar-based turbulence intensity retrievals
    International Journal of Microwave and Wireless Technologies, 2016
    Co-Authors: Albert C. P. Oude Nijhuis, Felix Yanovsky, Oleg A. Krasnov, H.w.j. Russchenberg, Christine Unal, Alexander Yarovoy
    Abstract:

    A new model is proposed on how to account for the inertia of scatterers in Radar-based turbulence intensity retrieval techniques. Rain drop inertial parameters are derived from fundamental physical laws, which are gravity, the buoyancy force, and the drag force. The inertial distance is introduced, which is a typical distance at which a particle obtains the same wind velocity as its surroundings throughout its trajectory. For the measurement of turbulence intensity, either the Doppler spectral width or the variance of Doppler mean velocities is used. The relative scales of the inertial distance and the Radar Resolution volume determine whether the variance of velocities is increased or decreased for the same turbulence intensity. A decrease can be attributed to the effect that inertial particles are less responsive to the variations of wind velocities. An increase can be attributed to inertial particles that have wind velocities corresponding to an average of wind velocities over their backward trajectories, which extend outside the Radar Resolution volume. Simulations are done for the calculation of measured Radar velocity variance, given a 3-D homogeneous isotropic turbulence field, which provides valuable insight in the correct tuning of parameters for the new model.

  • Turbulence intensity estimation using advanced Radar methods
    2015 European Radar Conference (EuRAD), 2015
    Co-Authors: Felix Yanovsky, A.c.p. Oude Nijhuis, Oleg A. Krasnov, C.m.h. Unal, H.w.j. Russchenberg, Alexander Yarovoy
    Abstract:

    This paper presents an advanced Radar method and novel algorithm for retrieving turbulence intensity from precipitation measurements, using coherent fully polarimetric Radar system. The algorithm computes the Eddy dissipation rate based on adaptive estimation of a Doppler spectrum width in the Radar Resolution volume and a variance of the mean Doppler velocity in space and in time. The adaptation consists in estimation and removal of nonturbulent contributions to all informative parameters based on reflected signal processing. The algorithm has been verified experimentally by comparing EDR values retrieved from Radar signals with in situ sonic anemometer measurements.

  • Assessment of Electromagnetic Requirements for UWB Through-Wall Radar
    2007 International Conference on Electromagnetics in Advanced Applications, 2007
    Co-Authors: Xiaodong Zhuge, T.g. Savelyev, Alexander Yarovoy
    Abstract:

    This paper investigates electromagnetic requirements for ultra-wideband (UWB) through-wall Radar. It includes the evaluation of propagation loss, dynamic range and Radar Resolution for typical through-wall scenarios. The evaluation results in analysis and comparison of different transmission schemes.

Svetlana Bachmann - One of the best experts on this subject based on the ideXlab platform.

  • ICASSP (2) - Spectral Analysis of Polarimetric Weather Radar Data with Multiple Processes in a Resolution Volume
    2007 IEEE International Conference on Acoustics Speech and Signal Processing - ICASSP '07, 2007
    Co-Authors: Svetlana Bachmann, Victor Debrunner, Dusan S. Zrnic, Mark Yeary
    Abstract:

    A new approach for the clear air velocity estimation in weather Radar is presented. A combination of nonparametric with parametric spectral analysis allows us to identify and extract multiple processes caused by different scatterer types within a single Radar Resolution volume. An example of clear air observed using an S-band dual polarization Radar is presented. Heretofore, migrating birds and wind-blown insects that are mixed within each Resolution volume caused such data to be unusable for meteorological interpretation. In this paper, we construct power spectral densities of polarimetric variables. We use the polarimetric spectral densities to differentiate the scatterer types within the observed Radar Resolution volume. We demonstrate how our combination of non-parametric and parametric spectral analysis can be used to retrieve the true wind velocity in situations with severe contamination by biological scatterers.

Dusan S. Zrnic - One of the best experts on this subject based on the ideXlab platform.

  • ICASSP (2) - Spectral Analysis of Polarimetric Weather Radar Data with Multiple Processes in a Resolution Volume
    2007 IEEE International Conference on Acoustics Speech and Signal Processing - ICASSP '07, 2007
    Co-Authors: Svetlana Bachmann, Victor Debrunner, Dusan S. Zrnic, Mark Yeary
    Abstract:

    A new approach for the clear air velocity estimation in weather Radar is presented. A combination of nonparametric with parametric spectral analysis allows us to identify and extract multiple processes caused by different scatterer types within a single Radar Resolution volume. An example of clear air observed using an S-band dual polarization Radar is presented. Heretofore, migrating birds and wind-blown insects that are mixed within each Resolution volume caused such data to be unusable for meteorological interpretation. In this paper, we construct power spectral densities of polarimetric variables. We use the polarimetric spectral densities to differentiate the scatterer types within the observed Radar Resolution volume. We demonstrate how our combination of non-parametric and parametric spectral analysis can be used to retrieve the true wind velocity in situations with severe contamination by biological scatterers.