Basic Experiments of Real-Time VLBI Using Public Communication Line

利用公共通信线路的实时VLBI基础实验

• 批准号: 10440064
• 负责人: NISHIO Masanori
• 金额: $ 2.82万
• 依托单位: KAGOSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10440064/
• 关键词: VLBI; REAL-TIME PROCESSING; PUBLIC COMMUNICATION LINES; DATA COMPRESSION; SIGNAL OF COMMUNICATION SATELLITES; COSMIC WATER MASER SOURCES; VARIATIONS OF ATMOSPHERIC TRANSMISSION DELAY; REAL-TIME DIAGOSIS

For real-time VIBL observations of the 19GHz beacon signals from geostationary satellites with the Kagoshima 6-m diameter and the Mizusawa 10-m diameter radio telescopes, a subsystem attached to the radio telescopes is developed, which consist of base-band frequency converters, data acquisition units, signals transmission units and a cross-correlator. The software for data transmission and cross-correlation is also developed. VLBI observations with the subsystem attached to the radio telescopes were made using the beacons waves of the geostationary satellites, where the baseline length was about 1300 km. We confirmed that the cross-correlation was obtained in real time. For the cross-correlation data, we have checked if the fluctuations of atmospheric propagation delay can be detected. Origins of the phase fluctuations included in the cross-correlation data were analyzed in detail, and we obtained following results ; (1) contribution of the receiver noise was negligibly small, (2) drif … More t of phase caused by the diurnal motion of the satellite and the effect of the frequency deviation of the beacon signal could be removed from the observed data, and (3) the frequency deviation of hydrogen maser oscillators installed in the radio telescopes as master oscillators was a main source of fast phase variation with the duration shorter than 10 sec, while its effect was negligible at the range of longer than 10 sec. We conclude the phase fluctuations with the duration from 10 to 100 sec are originated from the atmospheric disturbances. In addition, we conclude that smaller diameter antennas, such as 1-m diameter paraboloidal antennas, can be used for detection of the atmospheric disturbances.This project makes it clear that (1) the real-time diagnosis of the VLBI system is achieved with simple and low-cost devices, such as commercial-based A-D converters, personal computers and communication devices, (2) fluctuation of radio propagation delay caused by atmospheric disturbance is detectable by the VLBI observations of the beacon waves of the geostationary satellites, (3) a radio monitoring system of the atmospheric disturbance can be constructed with small diameter antennas, low-cost receivers and commercial-based data processing units. The results obtained by this project are published as papers and proceedings, such as IEICE Transaction, SPIE Proceedings, ISAP Proceedings and so on. A follow-up study of this project is in progress and further papers will be appeared. Less

针对鹿儿岛6米口径射电望远镜和水泽10米口径射电望远镜对地球静止卫星19GHz信标信号的实时VIBL观测，研制了一个附加在射电望远镜上的子系统，该子系统由基带频率转换器、数据采集单元、信号传输单元和互相关器组成。开发了数据传输和相互关联软件。与射电望远镜相连的子系统利用地球静止卫星的信标波进行了VLBI观测，基线长度约为1300公里。我们证实了相互关系是实时得到的。对于互相关数据，我们检查了是否可以检测到大气传播延迟的波动。详细分析了互相关数据中相位波动的来源，得到以下结果：(1)接收机噪声的贡献可以忽略不计；(2)卫星日运动和信标信号频率偏差的影响可以从观测数据中去除；(3)作为主振子安装在射电望远镜中的氢脉泽振荡器的频率偏差是快速相位变化的主要来源，持续时间小于10秒。在超过10秒的范围内，其影响可以忽略不计。我们认为，持续时间为10 ~ 100秒的相位波动是由大气扰动引起的。此外，我们还得出了直径较小的天线，如直径为1 m的抛物面天线，可以用于大气扰动的检测。本项目明确了(1)利用商用a - d转换器、个人计算机和通信设备等简单、低成本的设备实现VLBI系统的实时诊断；(2)利用对地静止卫星信标波的VLBI观测可以探测到大气扰动引起的无线电传播延迟波动；(3)利用小直径天线可以构建大气扰动无线电监测系统。低成本接收器和商业数据处理单元。该项目的研究成果已在IEICE Transaction、SPIE proceedings、ISAP proceedings等刊物上发表。该项目的后续研究正在进行中，并将发表进一步的论文。少

项目成果

M.Nishio 外6名: "Real-time VLBI System Using Telephone Network For On-line System Diagnosis"Proceedings of SPIE, Astronomical Telescope and Instrumentation 2000. 4015. 531-539 (2000)

M.Nishio 等 6 人：“使用电话网络进行在线系统诊断的实时 VLBI 系统”SPIE 论文集，天文望远镜和仪器 2000. 4015. 531-539 (2000)

K.Sato et al.: "Development of an Ultra Stable Fiber Optic Frequency Distribution System using an Optical Delay Line Module"IEEE Trans.I&M. Vol.49.1. 19-24 (2000)

K.Sato 等人：“使用光学延迟线模块开发超稳定光纤频率分配系统”IEEE Trans.I

S.Iguchi,N.Kawaguchi 外3名: "Development and Performance of the Terminal System for VLBI Space Observatory Programme(VSOP)"IEICE Trans.Commu.. E83-B・2. 406-413 (2000)

S.Iguchi、N.Kawaguchi 等 3 人：“VLBI 空间观测站计划（VSOP）终端系统的开发和性能”IEICE Trans.Commu.. E83-B·2（2000）。

Q.Lui,M.Nishio and T.Miyazaki: "Real-Time VLBI System Using Public Communication Lines"Proc.of the 2000 International Symposium on Antenna and Propagation. Vol.1. 381-384 (2000)

Q.Lui、M.Nishio 和 T.Miyazaki：“使用公共通信线路的实时 VLBI 系统”2000 年国际天线与传播研讨会论文集。

M.Nishio et al.: "Real-time VLBI System Using Telephone Network For On-line System Diagnosis"Proc.of SPIE. Vol.4015. 531-539 (2000)

M.Nishio 等人：“使用电话网络进行在线系统诊断的实时 VLBI 系统”Proc.of SPIE。