4. Technical Reports

4.1 Key Stone Project

Automatic Observation System (Takahiro Iwata)

VLBI is one of the most accurate technique for geodetic measurements. However, it is not suitable for daily observations because much man-power is necessary for both observations and data processing. The purpose of the Keystone project promoted by CRL is to detect regional crustal deformations, considered as precursors of large earthquakes, therefore continuous daily observations are strongly desirable. Especially high reliability is required for the system to perform the continuous observations not disturbed by instrument malfunctions. Fully automatic operation is also required. We have designed the KSP system so as to meet both these requirement.

Each station is equipped with two kinds of computers. One is a controlling computer which controls the observation instruments, such as an antenna and a recorder according to schedule prepared in advance. The other is a monitoring computer which gathers basic data, such as meteorological data, sytem noise temperature, and status of each instrument.

Central station
Koganei and Kashima function as a central station and a sub-central station. Both stations are equipped with concentrated controlling computers which control and monitor systems at each station via a computer network. An operator at the central or sub-central station can therefore know the status of each station.

Computer network
A WAN (Wide Area Network), which is a dedicated digital communication link, connects Kashima, Koganei, Miura and Tateyama. Furthermore we plan to have a backup digital link between Kashima and Tateyama. Each station is also equipped with a telecommunication line for data transfer. Remote operation through this line is planned to recover the computer system as a backup.

Data recording
The data recording is performed by the K4 data recorder built in the DMS-24 automatic tape changer. The DMS-24 enables operatorless observations for 24 hours. We aim to do real-time data transfer to the correlator at the central station in the future.

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