一种基于特征向量的无线电阵列校准方法及其在天来圆柱导航仪中的应用
An Eigenvector-based Method of Radio Array Calibration and Its Application to the Tianlai Cylinder Pathfinder
摘要：
我们提出了一种基于特征向量的射电干涉仪阵列校准的形式主义。在强主导点源存在的情况下，阵列的复增益可以通过取可见度矩阵的第一特征向量来获得。我们使用稳定的主成分分析（SPCA）方法来帮助分离的校准信号的离群值和噪声，以提高该方法的性能。该方法可以应用于天线的波束模型知之甚少的情况，并且对数据中的异常值或缺陷不敏感，并且具有较低的计算复杂度。因此，它特别适用于阵列的初始校准，可以作为更精确校准的初始点。将该方法应用于“天籁”实验的圆柱形寻路器，通过对中性氢（HI）红移21 cm发射的强度成像观测，利用大尺度结构中的重子声学振荡（BAO）特征测量暗能量状态方程.将该方法应用于亮射电源的凌日数据，成功地得到了阵元的复增益和东西方向（柱体短轴）的波束轮廓。
英文摘要：
We propose an eigenvector-based formalism for the calibration of radio interferometer arrays. In the presence of a strong dominant point source, the complex gains of the array can be obtained by taking the first eigenvector of the visibility matrix. We use the stable principle component analysis (SPCA) method to help separate outliers and noise from the calibrator signal to improve the performance of the method. This method can be applied with poorly known beam model of the antenna, and is insensitive to outliers or imperfections in the data, and has low computational complexity. It thus is particularly suitable for the initial calibration of the array, which can serve as the initial point for more accurate calibrations. We demonstrate this method by applying it to the cylinder pathfinder of the Tianlai experiment, which aims to measure the dark energy equation of state using the baryon acoustic oscillation (BAO) features in the large scale structure by making intensity mapping observation of the redshifted 21~cm emission of the neutral hydrogen (HI). The complex gain of the array elements and the beam profile in the East-West direction (short axis of the cylinder) are successfully obtained by applying this method to the transit data of bright radio sources.
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