IMPROVEMENTS OF ACCURACY OF DISPLACEMENT MEASUREMENTS USING GPS FOR MONITORING THE STABILITY OF SLOPES

为了提高位移测量的可靠性，利用全球定位系统，从散布在各种误差中的测量数据中检测出精确的位移是一项至关重要的任务。本研究探讨了提高GPS位移测量精度的两个重要问题：一是气象条件变化引起的大气延迟是影响测量误差的重要因素。提出了一种对其进行纠错的方法。将该方法应用于实际测量结果进行验证。第二个问题是传感器上方的障碍物对测量精度的影响。进行了现场调查，以揭示由于障碍物而导致准确度降低的原因。结果表明，双差的残差对测量精度有影响。在基线分析中，为了提高测量精度，忽略了引起稀释的卫星数据。提出了掩模法，并验证了两种方法都成功地提高了GPS位移监测的测量精度

In order to improve the reliability of displacement measurements, using the Global Positioning System, it is an essential task to detect the exact displacements from measurement data scattered among various types of errors. This research discusses two important issues concerning improvement of the accuracy of GPS displacement measurements.The first one is the atmospheric delay caused by changes in weather conditions as an important factor in the measurement errors. An error correction method for it has been proposed. The method was applied to practical measurement results in order to verify it.The second issue is an influence of obstacles above a sensor to the measurement accuracy. A field investigation was conducted to reveal the cause of the dilution of the accuracy due to the obstacles. It was found that the residual of the double difference affects on the accuracy. In order to improve the accuracy of measurements, the data of satellites which are caused the dilution was neglected on baseline analysis. The "mask procedure" was proposed to conduct it, and was verified to success improving the measurement accuracy.The both methods succeeded in improving the measurement accuracy of GPS displacement monitoring