RFI Cancellation for an Array Radio Astronomy System With Receiver Nonlinearity
RFI Cancellation for an Array Radio Astronomy System With Receiver Nonlinearity
复制标题
具有接收机非线性的阵列射电天文系统的 RFI 消除
作者：
Mahmoud E. Abdelgelil;H. Minn
由于射电天文信号非常微弱，射频干扰（RFI）是射电天文系统（RAS）的一个重要问题。主动无线系统（AWS）的快速扩展，以及对AWS和RAS频谱接入的更多需求，将导致具有强RFI的场景。这将导致RAS的低噪声放大器（LNA）在非线性区域工作，并带来更具挑战性的非线性RFI问题。我们用天线阵列解决了RAS的这个问题。当每个RAS接收器的LNA表现为非线性时，我们在RAS阵列处理输出处建立了一个新的信号模型。研究结果表明，现有的两种解决RAS阵列系统中RFI的方法无法处理非线性RFI。接下来，我们提出了两种改进的方法来解决非线性RFI。对RAS信号相关估计的平方误差进行了分析。数值结果表明，非线性RFI的严重影响和所提出的方法保持平方误差几乎与线性系统一样低的能力。
Radio frequency interference (RFI) is an important problem for a radio astronomy system (RAS) due to the very weak radio astronomical signals. Rapid expansions of active wireless systems (AWSs), as well as more demands for spectrum access by both AWS and RAS will result in scenarios with strong RFI. This will cause RAS’s low-noise amplifier (LNA) to operate in a nonlinear region and impose a more challenging nonlinear RFI issue. We address this issue for RAS with the antenna array. We develop a new signal model at the output of RAS array processing when the LNA at each RAS receiver behaves nonlinearly. We show that the two existing methods to address RFI in RAS array systems fail to deal with the nonlinear RFI. Next, we propose two modified methods to address the nonlinear RFI. Analysis of the squared error of the RAS signal correlation estimate is also presented. The numerical results show the severe effects of nonlinear RFI and the capability of the proposed methods to keep the squared error almost as low as that of a linear system.