A Radio Interferometric Correlator Based on Graphics-Processing Units

— A correlator capable of processing data streams at a maximum rate of 16 Gb/s from each station in quasi-real time mode has been developed to process observations on new RT-13 radio telescopes of the Quasar VLBI network. The total data stream at the correlator input is as large as 96 Gb/s. The correlator is software-controlled and implements the FX processing algorithm. Graphical processing units manufactured by NVIDIA are used to perform the most laborious operations: fast Fourier transform, spectrum multiplication and addition, and extraction of phase calibration signals. The correlator, which was produced in 2014, has been processing observations of the Badary and Zelenchukskaya Observatories of the Quasar VLBI network for more than 2 years and a number of UT1-UTC World Time estimates have been obtained.