Improvement of PCAL Signal Distribution on RT-32 Radio Telescopes of ”Quasar” VLBI Network
Proceedings of the 23rd European VLBI Group for Geodesy and Astrometry Working Meeting Proceedings of the 23rd European VLBI Group for Geodesy and Astrometry, Gothenburg, Sweden , 20–23 (2017)
Keywords: VLBI, radio telescope, phase calibration, PCAL, Svetloe stationFull text
Using multi-tone phase calibration in VLBI observations can potentially give better results than the conventional single-tone technique. At the same time it increases the requirements to phase calibration (PCAL) signal quality. Distortions of PCAL signal can eliminate all benefits of multi-tone calibration up to making it completely unusable. To prevent this and to examine the condition of PCAL signals at "Quasar" VLBI network stations we performed a series of test measurements with RT-32 radio telescopes. The measurements included estimation of amplitudes and phases of all PCAL tones in all channels in standard S/X geo mode and their dependence on the antenna elevation. The results were used to perform troubleshooting on the stations which has already resulted in a significant improvement of PCAL signal quality which, in turn, is expected to lead to better calibration results, both singleand multi-tone. The paper presents brief report of the measurements taken and the results achieved.