高速サンプリングGPS観測のノイズ評価

抄録

We seek the way of high-speed sampling GPS observation as a broad-band displacementseismomete. For this purpose it is necessary to evaluate the noise level inherent to the GPS observation due to ionospheric and tropospheric effects, multi-path and satellite configuration. In this study, we develop a stand-alone data acquisition system for the continuous high-speed sampling GPS observation after overcoming the troubles in automatic handling the large volume of GPS data. Four GPS stations are establised in Hokkaido area and the period of each observation is half year to year and half. Telemetry of the GPS data using the public telephone line is tested and completed. GPS station coordinates are calculated every second by the GPS kinematic method. Noise reduction for each noise source has been made, and noise levels of horizontal and vertical components after the reduction are about ±4mm, ±7mm, respectively in the case of 150km baseline length. Noise levels of various baseline lengths are also evaluated in different period ranges. These estimates of noises prove that the earthquake larger than JMA magnitude 5.9 can be detected at a GPS station 60km away from the epicenter.