Direct wide-field radio imaging in real-time at high time resolution using antenna electric fields
Direct wide-field radio imaging in real-time at high time resolution using antenna electric fields
复制标题
使用天线电场以高时间分辨率实时直接进行宽视场无线电成像
DOI：
10.1093/mnras/stz3028
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发表时间：
2020
影响因子：
4.8
通讯作者：
Bowman, Judd
中科院分区：
文献类型：
--
作者：
Kent, James;Beardsley, Adam P;Bester, Landman;Gull, Steve F;Nikolic, Bojan;Dowell, Jayce;Thyagarajan, Nithyanandan;Taylor, Greg B;Bowman, Judd
最近演示的实时直接成像无线电干涉测量相关器是射电天文学的一种新能力。然而，宽场成像与这种方法是具有挑战性的，因为宽场效应和阵列的非共面性降低图像质量，如果不补偿。在这里，我们提出了一种替代的直接成像相关策略，使用直接傅立叶变换（DFT），建模为线性算子，便于DFT矩阵和来自每个天线的电场的向量之间的矩阵乘法。这为宽场和非共面效应提供了完美的校正。当使用长波长阵列（LWA）的数据实现时，它提供了与先前演示的直接成像技术相当的计算性能，尽管理论上具有更高的浮点成本。它还具有其他好处，例如成像稀疏阵列和控制天空坐标成像，允许在图像上放置可变像素。在实践中，当在合适的阵列上实施时，它是一种高度灵活和高效的直接无线电成像方法。一个功能的电场直接成像架构使用DFT的，旁边的宽场成像技术的探索类似于那些在基于可测量性的成像，并解释为什么他们不适合直接与数字化的电场数据成像。DFT成像方法证明从LWA望远镜的真实的数据，旁边的详细的性能分析，以及其适用于其他阵列的探索。
The recent demonstration of a real-time direct imaging radio interferometry correlator represents a new capability in radio astronomy. However, wide-field imaging with this method is challenging since wide-field effects and array non-coplanarity degrade image quality if not compensated for. Here, we present an alternative direct imaging correlation strategy using a direct Fourier transform (DFT), modelled as a linear operator facilitating a matrix multiplication between the DFT matrix and a vector of the electric fields from each antenna. This offers perfect correction for wide field and non-coplanarity effects. When implemented with data from the Long Wavelength Array (LWA), it offers comparable computational performance to previously demonstrated direct imaging techniques, despite having a theoretically higher floating point cost. It also has additional benefits, such as imaging sparse arrays and control over which sky coordinates are imaged, allowing variable pixel placement across an image. It is in practice a highly flexible and efficient method of direct radio imaging when implemented on suitable arrays. A functioning electric field direct imaging architecture using the DFT is presented, alongside an exploration of techniques for wide-field imaging similar to those in visibility-based imaging, and an explanation of why they do not fit well to imaging directly with the digitized electric field data. The DFT imaging method is demonstrated on real data from the LWA telescope, alongside a detailed performance analysis, as well as an exploration of its applicability to other arrays.
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LOFAR 波束形成器：实施和性能分析
DOI：
--
发表时间：
2011
期刊：
European Conference on Parallel Processing
影响因子：
--
作者：
J. Mol;J. Romein
通讯作者：
J. Romein
影响因子：
4.8
作者：
A. Beardsley;N. Thyagarajan;J. Bowman;M. Morales
通讯作者：
A. Beardsley;N. Thyagarajan;J. Bowman;M. Morales
影响因子：
4.8
作者：
N. Thyagarajan;A. Beardsley;J. Bowman;M. Morales
通讯作者：
N. Thyagarajan;A. Beardsley;J. Bowman;M. Morales
MWA 捆绑阵列处理 I：校准和波束形成
影响因子：
6.3
作者：
S. Ord;S. Tremblay;S. McSweeney;N. Bhat;C. Sobey;D. Mitchell;Paul J. Hancock;Franz Kirsten
通讯作者：
Franz Kirsten
影响因子：
10.6
作者：
JACKSON, JI;MEYER, CH;MACOVSKI, A
通讯作者：
MACOVSKI, A