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Volume 36 (1990)
- Issue 4 Pages 219-
- Issue 3 Pages 143-
- Issue 2 Pages 73-
- Issue 1 Pages 1-
Volume 36, Issue 2
Displaying 1-6 of 6 articles from this issue
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Atsushi YAMAMOTO, Ichiro TOMIZAWA, Takeo YOSHINO, Michito IMAE, Hiroo ...1990 Volume 36 Issue 2 Pages 73-84
Published: July 25, 1990
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe receiving antenna position error is one of the considerable error sources of the GPS time comparison. A simple relative positioning method using the GPS time comparison data themselves is suggested to improve the time comparison precision. This method is applied to the time comparison values between the Communications Research Laboratory (CRL) and the Sugadaira Space Radio Observatory (SSRO), University of Electro-Communications. As a result, the receiving antenna position at the SSRO is determined with a precision of 1.4 m assuming the position of the CRL is known. The RWMS (the Root Weighted Mean Squared) error of the time comparison results is reduced from 50.3 ns of the observed values to 7.8 ns of the post-fit residuals.View full abstractDownload PDF (1005K) -
Makoto MURAKAMI1990 Volume 36 Issue 2 Pages 85-100
Published: July 25, 1990
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe orbits of the GPS satellites were determined using tracking data taken at stations in Japan. Global data by CIGNET were also used with a light weight for better geometric strength. Emphasis is put on the baseline repeatability around Japan. Short term repeatability as good as a few parts in 10 million (10-7) was achieved for each component of the baseline vector. The repeatability of the length component was better than 0.1 ppm. The results suggest that further refinement of the accuracy up to 10-8 level is possible by improving the software and by carefully choosing the locations of the tracking sites of Japan.View full abstractDownload PDF (1586K) -
Shuzo TAKEMOTO, Kazuro HIRAHARA, Torao TANAKA1990 Volume 36 Issue 2 Pages 101-108
Published: July 25, 1990
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSOne year observation of crustal strains using a portable laser extensometer system was carried out at Kishu in Kui Peninsula, Southwestern Japan, during 19871988. The system comprising a frequency-stabilized laser source and two Michelson-type inter-ferometers was designed to detect two-axial horizontal linear strains simultaneously. The laser beam emitted from the laser source was divided into two beams for con-structing a set of orthogonal interferometers (L-1: N80°E and L-2: N10°W). The L-1 component was kept in an air-tight stainless steel pipe having an effective length of 15.42 m. On the other hand, the L-2 component 2.82 m in length was not sealed by an air-tight pipe but opened in the air. Resolving powers of these extensometers were 1.03×10-9 and 5.62×10-9, respectively. With regard to the L-2 component, the relation between the apparent strain (s) and the change of atmospheric pressure (P) was determined as follows, ε(×10-6)=2.13×P(mb). (1)After eliminating the effect of atmospheric pressure by applying (1) to the data of L-2, strain changes of the order of 10-8 could be detected. The L-1 component enabled strain changes of the order of 10-9 to be investigated. Strain accumulations obtained from L-1 and L-2 were 1.4×108/day and 6.5×10-8/day, respectively. Tidal strains were analyzed by applying the program 'BAYTAP-G' to the 152 days records of L-1 and L-2. Amplitudes and phase lags of 12 major constituents were determined.View full abstractDownload PDF (703K) -
Naosuke SEKIGUCHI1990 Volume 36 Issue 2 Pages 109-114
Published: July 25, 1990
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSA theoretical relation between the rates of the "Microscopic" and "Macroscopic" Chandlerian Periods is obtained basing on the assumption that the polar wobble is excited by a stationary random motion of the excitation pole. It is found that these two periods do not necessarily coincide with each other, and their difference is dependent on the autocovariance function of the motion of the excitation pole of the polar wobble. An example of the excitation model, which conforms itself to the existing values of the "Microscopic" and the "Macroscopic" Chandlerian Periods and the radius of the polar wobble, is presented.View full abstractDownload PDF (513K) -
Fumiaki KIMATA, Masaru NAKAMURA, Takashi OKUDA1990 Volume 36 Issue 2 Pages 115-117
Published: July 25, 1990
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe positioning by differential GPS was repeated between Nagoya and Takayama (110 km north of Nagoya) for the study of GPS positioning accuracy. The error by ordinary point positioning in GPS was not only large ±10 m but also quite dependent on satellite constellation. On the other hand the differential GPS showed errors as small as ±1 m and ±3 m in horizontal distance and in height, respectively. It is also noted that the positions determined by the differential GPS are almost independent of satellite constellation.View full abstractDownload PDF (367K) -
Fumiaki KIMATA1990 Volume 36 Issue 2 Pages 119-122
Published: July 25, 1990
Released on J-STAGE: September 07, 2010
JOURNAL FREE ACCESSThe two instruments, Geomensor and ME5000 are capable of measuring distance with a very high resolving power of sub-mm. The Geomensor uses a white ray from a xenon lamp, whereas the ME5000, a red helium-neon laser. These were simultaneously used along the same baseline. On a 1.6 km baseline, the change of line length due to atmospheric change was about 8 mm during seven hours. It was reduced within 0.9 mm by a multi-wave correction. In another experiment on a 3.6 km baseline, the difference between corrected line lengths measured on two consecutive days was less than 1 mm.View full abstractDownload PDF (513K)
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