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제도흥,이원규,김수연,정문희,송민규,정태현,변도영,김승래,손봉원,위석오,한석태,강용우,Je, Do-Heung,Lee, Won-Kyu,Kim, Soo-Yeon,Chung, Moon-Hee,Song, Min-Kyu,Jung, Taehyun,Byun, Do-Young,Kim, Seung-Rae,Sohn, Bong-Won,Wi, Seog-Oh,Han, Seog-T 한국천문학회 2013 天文學論叢 Vol.28 No.3
A fiber-optic reference signal transmission system, which transmits the 1.4 GHz reference signal from H-maser to receiver cabin in radio telescopes, was adopted for compensating the phase changes due to temperature variation and antenna movement. At the first experiment, the remote signal's phase changed more than 15 degrees at 1.4 GHz. We found unstable components in sub-system experiments and replaced them. The main cause of unstable phase stability was the unaligned polarization axis between Laser Diode and Mach-Zehnder Modulator (MZM). The improved system stability showed $1{\times}10^{-16}$ allan standard deviation at 1,000 sec integration time with the antenna fixed. When the antenna moves in the azimuth axis, the 1.4 GHz remote signal showed the phase change smaller than 0.2 degrees.
한국우주전파관측망(KVN)을 위한 시각 시스템 구축과 성능측정
오세진,제도흥,이창훈,노덕규,정현수,변도영,김광동,김효령,정구영,안우진,황정욱,Oh, Se-Jin,Je, Do-Heung,Lee, Chang-Hoon,Roh, Duk-Gyoo,Chung, Hyun-Soo,Byun, Do-Young,Kim, Kwang-Dong,Kim, Hyo-Ryung,Jung, Gu-Young,Ahn, Woo-Jin,Hwang, Jeong 한국천문학회 2007 天文學論叢 Vol.22 No.4
In this paper, we describe the proposed KVN (Korean VLBI Network) clock system in order to make the observation of the VLBI effectively. In general, the GPS system is widely used for the time information in the single dish observation. In the case of VLBI observation, a very high precise frequency standard is needed to perform the observation in accordance with the observation frequency using the radio telescope with over 100km distance. The objective of the high precise clock system is to insert the time-tagging information to the observed data and to synchronize it with the same clock in overall equipments which used in station. The AHM (Active Hydrogen Maser) and clock system are basically used as a frequency standard equipments at VLBI station. This system is also adopted in KVN. The proposed KVN clock system at each station consists of the AHM, GPS time comparator, standard clock system, time distributor, and frequency standard distributor. The basic experiments were performed to check the AHM system specification and to verify the effectiveness of implemented KVN clock system. In this paper, we briefly introduce the KVN clock system configuration and experimental results.