  Radio transient discovery using next generation radio telescopes will pose
several digital signal processing and data transfer challenges, requiring
specialized high-performance backends. Several accelerator technologies are
being considered as prototyping platforms, including Graphics Processing Units
(GPUs). In this paper we present a real-time pipeline prototype capable of
processing multiple beams concurrently, performing Radio Frequency Interference
(RFI) rejection through thresholding, correcting for the delay in signal
arrival times across the frequency band using brute-force dedispersion, event
detection and clustering, and finally candidate filtering, with the capability
of persisting data buffers containing interesting signals to disk. This setup
was deployed at the BEST-2 SKA pathfinder in Medicina, Italy, where several
benchmarks and test observations of astrophysical transients were conducted.
These tests show that on the deployed hardware eight 20MHz beams can be
processed simultaneously for $\sim$640 Dispersion Measure (DM) values.
Furthermore, the clustering and candidate filtering algorithms employed prove
to be good candidates for online event detection techniques. The number of
beams which can be processed increases proportionally to the number of servers
deployed and number of GPUs, making it a viable architecture for current and
future radio telescopes.
