Modernized Device for Reading Angular Coordinates of RT-32

V. Yu. Bykov

Transactions of IAA RAS, issue 58, 3–10 (2021)

DOI: 10.32876/ApplAstron.58.3-10

Keywords: radio telescope, position sensor, angle-to-code converter, 5-BVT, inductosyn, rotating transformer

Abstract

Angular coordinates taking device (DACT) provides taking of the angular position from primary angle sensors of the RT-32. DACT is a part of the pointing system of the RT-32 antenna system and largely determines its accuracy. The last update of the DACT was more than 10 years ago for main reflector and more than 17 years ago for subreflector. DACT measures the angular coordinate with a resolution of 20 bits for the main reflector and 14 bits for the subreflector. The amplitude of the inductosyn nonlinearity characteristic is about (20 ÷ 40)″. The coordinate update rate is 35 Hz. These parameters meet the accuracy requirements for observations at the main operating wavelengths of the RT-32 radio telescope, however, for successful observations at shorter wavelengths, these parameters need to be improved. It is necessary to increase the coordinate measurement resolution for reflectors, decrease the amplitude of the inductosyn nonlinearity characteristic, and increase the coordinate measurement frequency. Studies of the features of the DACT operation have been carried out. The problems of technical solutions that limit the realization of the potential accuracy of measuring coordinates using standard angle sensors of the RT-32 are identified, and ways to eliminate them are worked out. Based on the results obtained, a deep modernization of the DACT hardware and software was carried out. As a result of the modernization of the DACT, the following characteristics were achieved: the angular coordinate resolution was increased to 24 bits for the main reflector and up to 16 bits for the sub reflector; the amplitude of the inductosyn nonlinearity characteristic is reduced to (7 ÷ 10)″; coordinate update rate increased to 125 Hz. The upgraded DACT are installed on all radio telescopes of the VLBI network Quazar.

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