Design, implementation, and qualification of high-performance time and frequency reference for the MeerKAT telescope

Abstract

The details of the MeerKAT radio telescope's time and frequency reference subsystem that enables sampling via low-jitter, low-drift microwave clock signals, and absolute timing (≤5 ns accurate) are discussed. The subsystem's microwave and pulse per second transmission parts are now fully qualified and commissioned for the ultra high frequency (UHF) and L-bands and also provide for a 100-MHz interface and timing interfaces for S-band receivers that were installed. The subsystem includes a cable measurement system called the Karoo array timing system (KATS). Performance and differences on different bands and seasonal drift of the cable delay measurement of KATS are reported. A time scale called the Karoo Telescope Time (KTT) (which is estimated from tracking a few atomic clocks via new software) and the issuing of timing bulletins to users have been largely implemented and verified. Absolute timing calibration and linkage of KTT to the global positioning system time scale and to different UTC(k) realizations of the Coordinated Universal Time (UTC) instances are described. The subsystem uniquely enables high-fidelity sampling and stable tied array configuration. The latter configuration enables timing and transient science over time spans of 5 to 10 years. Simultaneous subarraying is supported. The backend is unique for radio telescopes in terms of being very deterministic as far as timing is concerned.

The MeerKAT Pulsar Timing Array: first data release

“…For accurate pulsar timing, the drifting offset of KTT relative to UTC is measured through a system described in detail in Burger et al (2022), and results in the production of a clock correction 5 . This correction is applied using pulsar timing software (in our case 2), which corrects for the resultant offset in the pulse arrival times to a precision of less than 4.925 ns (Burger et al 2022).…”