Browsing by Author "Schroeder, Anja"
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- ItemOpen AccessA scalable database model of RFI data for the MeerKAT/SKA radio telescope(2024) Balekaki, Gerald Nathan; Kuttel, Michelle; Blyth, Sarah; Schroeder, AnjaIn radio astronomy, radio frequency interference (RFI) refers to any signal captured by a radio telescope that did not originate from the observed target in the sky. RFI from terrestrial and other sources is a recognized problem that contaminates the desired signal and must be tracked and ultimately removed. RFI corrupts observed data and may even damage radio telescope equipment. Astronomers, therefore, seek to store data on RFI to mitigate or prevent future interference events. At the MeerKAT radio telescope (a precursor to the Square Kilometre Array, and one of the largest and most sensitive radio telescopes in the world to date), RFI is captured in different formats using a variety of devices including telescopes, sensors and scanners; however, the combination of data from these multiple sources does not only yield storage problems but also data integration challenges. In this work, we present two designs for the scalable database model. In the first design, RFI data is stored in multiple databases (PSQL, SciDB, and Accumulo). Our findings indicate that PSQL outperforms both SciDB and Accumulo. Consequently, in the second design (alternative), all RFI data is stored exclusively in PSQL. However, we observed that the performance of the alternative model is impacted by the transformation of SciDB (array data) and Accumulo (key-value data) into PSQL (relational data). Our results recommend storing RFI data in its appropriate database rather than transforming it into another format, as this approach boosts the model's performance. Our model demonstrates a response time of less than 12 seconds for 1 MB RFI data (bulk request), with latency below 0.14 seconds—well within the acceptable maximum latency of 1 second in scalable databases. We found that the native database API is slightly faster (5%) than a third-party API, with no significant impact on the model's performance. In addition, this work indicates the direction for improvement in join queries involving disparate databases, which remains a limitation in heterogeneous environments. Our model facilitates fast queries across various databases, underscoring the importance of storing each data type in the appropriate database system. Lastly, our RFI database model offers good performance and scales effectively with increasing data volumes, multiple users, and varying workloads, making it suitable for the MeerKAT and SKA radio telescopes.
- ItemOpen AccessRFI monitoring for the MeerKAT Radio Telescope(2015) Schollar, Christopher; Blyth, Sarah-Louise; Kuttel, Michelle Mary; Schroeder, AnjaSouth Africa is currently building MeerKAT, a 64 dish radio telescope array, as a pre-cursor for the proposed Square Kilometre Array (SKA). Both telescopes will be located at a remote site in the Karoo with a low level of Radio Frequency Interference (RFI). It is important to maintain a low level of RFI to ensure that MeerKAT has an unobstructed view of the universe across its bandwidth. The only way to effectively manage the environment is with a record of RFI around the telescope. The RFI management team on the MeerKAT site has multiple tools for monitoring RFI. There is a 7 dish radio telescope array called KAT7 which is used for bi-weekly RFI scans on the horizon. The team has two RFI trailers which provide a mobile spectrum and transient measurement system. They also have commercial handheld spectrum analysers. Most of these tools are only used sporadically during RFI measurement campaigns. None of the tools provided a continuous record of the environment and none of them perform automatic RFI detection. Here we design and implement an automatic, continuous RFI monitoring solution for MeerKAT. The monitor consists of an auxiliary antenna on site which continuously captures and stores radio spectra. The statistics of the spectra describe the radio frequency environment and identify potential RFI sources. All of the stored RFI data is accessible over the web. Users can view the data using interactive visualisations or download the raw data. The monitor thus provides a continuous record of the RF environment, automatically detects RFI and makes this information easily accessible. This RFI monitor functioned successfully for over a year with minimal human intervention. The monitor assisted RFI management on site during RFI campaigns. The data has proved to be accurate, the RFI detection algorithm shown to be effective and the web visualisations have been tested by MeerKAT engineers and astronomers and proven to be useful. The monitor represents a clear improvement over previous monitoring solutions used by MeerKAT and is an effective site management tool.