Methods for Measuring the Signal of the Phase Calibration of the VLBI Radio Telescopes

Аннотация

In the majority of modern radio telescopes, which are used for radio interferometry with very long baselines, a special signal is introduced into the signal chain for the phase calibration of the equipment. This signal is used during the correlation processing of the radio-astronomy observations for obtaining a synthesized response when it is required to match the signals of several frequency channels by phase and delay and to ensure control over the working capacity of the equipment and the phase stability of the signal chain during the preparation and implementation of observations. Isolation of the phase-calibration signal in the recorded data requires considerable computation resources. In this case, the computation volume increases with increasing recorded frequency domain, which can amount to several gigahertz for modern radio telescopes, such as RT-13 of the “Quasar” VLBI network. In this work, the well-known methods for measuring the parameters of the phase-calibration signal are considered, their precision is estimated, the computation efficiencies are compared, and the disadvantages of the available measuring algorithms are shown. An improved method allowing one to significantly save the computation cost without the measuring-accuracy loss is proposed, which softens hardware requirements and speeds up computations.