A real-time radio transient pipeline for ARTS

ARTS is a new instrument designed to discover transient astronomical sources in the radio spectrum. To operate, it will require a high-performance radio transient pipeline, capable of processing hundreds of data streams in real-time, at a data rate of 36 GB/s. What makes the processing of these data streams challenging is the fact that radio signals received from space are dispersed by the interaction with the inter-stellar medium, and dispersion is a function of the distance between source and receiver. Because the distance of yet to discover objects is not known in advance, every data stream needs to be processed for thousands of trial distances, an extremely time consuming process. In this paper we introduce and describe a prototype for the ARTS radio transient pipeline. Our proposed pipeline is highly parallel and uses Graphics Processing Units as accelerators for its computational kernels. We test the pipeline on two different and widely used GPUs, the HD7970 from AMD and the K20X from NVIDIA, and show linear scalability and real-time performance on both. Using these performance results, we provide an estimate on the size of the system necessary to implement ARTS, and a lower bound on its power consumption. The results of this paper are also relevant in the context of designing the Square Kilometer Array.