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A real-time spatial RFI mitigation experiment has been conducted with an ASKAP test array in Australia at GPS L2 frequencies. The goal of the study was to observe and image a bright astronomical source in a corrupted environment. The RFI spatial information was estimated in real-time with Phased Array Feed sample Array Covariance Matrices in order to update a spatial filter based on subspace projection...
We investigate the bias of the Spectral Kurtosis Estimator induced by the quantization and bit truncation of the accumulated spectral power, which are standard signal manipulation operations performed by radio astronomy instruments that produce Power Spectral Density (PSD) estimates by means of sequential Discret Fourier Transform (DFT) operations. We demonstrate that these bias may be properly accounted...
As radio interference becomes pervasive, new methods might help to preserve reception of weak radio astronomical sources. When there is powerful interference that overlaps the desired weak signal in the frequency and time domains, spatial mitigation offers a potential solution. However, when the powerful interference and desired weak signal also exhibit similar — possibly identical — spatial signatures,...
Phased array radio telescopes allow for the filtering of Radio Frequency Interference (RFI) in the spatial domain. Spatial filters are advantageous in radio astronomy when the separation between RFI and astronomical sources cannot be made in the time or frequency domains. Consequently, the mitigation of the RFI relies on the quality of its spatial signature vector (SSV) estimation. The latter depends...
The increasing spectrum occupancy is a serious threat for highly sensitive astronomical measurement at radio frequencies. The deployment of array radio telescopes allows the exploitation of spatial information regarding sources of radio frequency interference (RFI) in order to filter them out of astronomical data and theoretical recover uncorrupted time and frequency data. This paper introduces the...
The ASKAP radio telescope in Australia is the first synthesis imaging array to use phased-array feeds (PAFs). These permit wider fields of view and new modalities for radio-frequency interference (RFI) mitigation. Previous work on imaging-array RFI cancellation has assumed that processing bandwidths are very narrow, and correlator integration times are short. However, these assumptions do not necessarily...
Array radio telescopes are suitable for the implementation of spatial filters. These filters present the advantage of canceling potential radio frequency interference (RFI) while recovering uncorrupted Time-Frequency data, of interest to astronomers. Although information regarding the sources of RFI can be a priori known or reliably inferred, the complexity of radio telescope systems randomizes the...
Radio astronomical observations are increasingly corrupted by radio frequency interference (RFI). Phased antenna array radio telescopes allow the recovering of spatial information of RFI and cosmic sources. Using this information, spatial signal processing techniques can limit the impact of the incoming interferences. In this article, we present an RFI mitigation technique, based on an oblique projector.
Radio astronomical observations are increasingly corrupted by radio frequency interferences (RFIs), and real time filtering algorithms are becoming essential. In this article, it is shown how spatial processing techniques can limit the impact of the incoming RFIs for phased array radio telescopes. The proposed approaches are based on estimation of the RFI spatial signature. It requires the diagonalization...
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