Optimisation of Convolution of Multiple Different Sized Filters in SKA Pulsar Search Engine

Abstract

Pulsar search is one of the main tasks for the Square Kilometre Array (SKA) central signal processor (CSP) sub-element. Because most of the pulsar details are unknown, many pulsar search approaches are employed. The main compute-intensive application of the pulsar search modules is the matched filter group, which convolves the input signals with a group of filters. High-performance designs on FPGAs have been proposed that can process multiple large filters efficiently. But given that in many applications, including the here targeted pulsar search, filters have different sizes, there is a high potential for optimisation. This paper investigates the optimisation of general matched filtering design for the SKA pulsar search engine. The influence of changing the number of filters and the difference in sizes is analysed. The general implementations in time-domain (TD) and frequency-domain (FD) are optimised, employing the longest processing time (LPT) first rule to distribute filter templates across filter processing pipelines. The proposed design is employed to implement the matched filter groups in two SKA pulsar modules. The results show that the optimisation can provide up to 2.1x speedup in TD and 1.2x speedup in FD.