The Experts below are selected from a list of 2499 Experts worldwide ranked by ideXlab platform

K. Oysted - One of the best experts on this subject based on the ideXlab platform.

Helmut Schmid - One of the best experts on this subject based on the ideXlab platform.

Michael Davies - One of the best experts on this subject based on the ideXlab platform.

  • Sparsity-based autofocus for undersampled synthetic aperture radar
    IEEE Transactions on Aerospace and Electronic Systems, 2014
    Co-Authors: Shaun I. Kelly, Mehrdad Yaghoobi, Michael Davies
    Abstract:

    Motivated by the field of compressed sensing and sparse recovery, nonlinear algorithms have been proposed for the reconstruction of synthetic-aperture-radar images when the phase history is undersampled. These algorithms assume exact knowledge of the system acquisition model. In this paper we investigate the effects of acquisition-model phase errors when the phase history is undersampled. We show that the standard methods of autofocus, which are used as a Postprocessing Step on the reconstructed image, are typically not suitable. Instead of applying autofocus in Postprocessing, we propose an algorithm that corrects phase errors during the image reconstruction. The performance of the algorithm is investigated quantitatively and qualitatively through numerical simulations on two practical scenarios where the phase histories contain phase errors and are undersampled.

  • Auto-focus for under-sampled synthetic aperture radar
    Sensor Signal Processing for Defence (SSPD 2012), 2012
    Co-Authors: Shaun I. Kelly, Mehrdad Yaghoobi, Michael Davies
    Abstract:

    We investigate the effects of phase errors on undersampled synthetic aperture radar (SAR) systems. We show that the standard methods of auto-focus, which are used as a Postprocessing Step, are typically not suitable. Instead of applying auto-focus as a post-processor we propose using a stable algorithm, which is based on algorithms from the dictionary learning literature, that corrects phase errors during the reconstruction and is found empirically to recover sparse SAR images. (5 pages)

Luo Dai-sheng - One of the best experts on this subject based on the ideXlab platform.

Peyman Milanfar - One of the best experts on this subject based on the ideXlab platform.

  • ICASSP (4) - Improved spectral analysis of nearby tones using local detectors
    Proceedings. (ICASSP '05). IEEE International Conference on Acoustics Speech and Signal Processing 2005., 1
    Co-Authors: Morteza Shahram, Peyman Milanfar
    Abstract:

    This paper concerns the problem of resolvability power in the frequency domain. The canonical case of interest is to distinguish whether the received noise-corrupted signal is a single-frequency sinusoid or a two-frequency sinusoid, where the amplitudes, phases and frequencies are unknown to the receiver. Using a model-based hypothesis testing approach, we quantify a measure of attainable resolution between sinusoids with nearby frequencies, in the presence of noise. An explicit relationship is derived for the minimum detectable difference between the frequencies of two tones, for any particular false alarm and detection rate, and at a given SNR. An associated algorithm is proposed that produces significantly better performance compared to the standard subspace-based methods like MUSIC and can be effectively used in practice as a Postprocessing Step for the existing spectral estimation methods.