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Precise timescale, frequency, and time-transfer technology for the Square Kilometer Array

Abstract. The Square Kilometre Array (SKA) is a next-generation radio astronomy facility that will revolutionize our understanding of the Universe and the laws of fundamental physics. To achieve the intended objectives, it needs a stable reference frequency and accurate timing signals at each digitizer. These references are used for digitizing astronomical signals received from the receptors. The stability and accuracy of these references are highly important for coherently sampling the astronomical data. They are distributed using long-distance fibers that are susceptible to environmental perturbations, which makes meeting the requirements a challenge. The system overcomes these perturbations by actively stabilizing the noise during fiber transmission to achieve the required reference signal stability and sub-nanosecond level of timing accuracy. We collect together summary descriptions of the sub-systems designed for distributing the reference frequency and timing signals for each telescope, to provide an overview of the whole timing and frequency system for the SKA.