| Description: | Radio Frequency Interference (RFI) will be an important problem for all upcoming FRB surveys, including the Square Kilometre Array. Our current real-time search for FRBs using the Westerbork Synthesis Radio Telescope (WSRT) and the Apertif Radio Transient System (ARTS) is no exception. Even with a radio quiet zone around WSRT, the generation of RFI is becoming increasingly part of anthropic activities. Furthermore, our sky is populated by a growing number of satellites for world-wide telecommunication. Without RFI mitigation strategies, spurious bright RFI can align at higher DM, which is interpreted by our search pipeline as an FRB trigger.
Our real-time requirement translates into the need for RFI mitigation methods that are fast and simple, while also being robust enough to cope with a partial view of the data. The image compares example data recorded at WSRT with and without RFI cleaning. The top row shows the data that caused the false positive triggers, marked by various bright RFI. The bottom row shows the same data after cleaning outliers in both frequency and time–which does not cause the search pipeline to trigger anymore.
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