다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Statistics for Spatial Data.

The Multi-GNSS Experiment (MGEX) of the International GNSS Service (IGS) - Achievements, prospects and challenges

Bernese GNSS Software Version 5.2

Geodetic measurements obtained with the Global Positioning System (GPS) are increasingly more widely applied in geophysical studies. In this paper, we review the changes to the technology of GPS geodesy over the last five years that are responsible for this increased applicability. We survey geophysical investigations employing GPS to measure coseismic, postseismic, and interseismic deformation; plate motion and crustal deformation at plate boundaries; volcano deformation; and the deformation associated with glacial isostatic adjustment and its application to sea-level studies. We emphasize the use of GPS determinations for the modeling of this wide variety of geophysical phenomena. We also discuss the recent advent of permanent GPS networks for regional geophysical studies, as well as the possible future of GPS surveying in light of the recent advances.

http://gps-rs.scg.ulaval.ca/pdf/annurev.earth.25.1%201997%20Segall%20-%20extrait.pdf

Gps applications for geodynamics and earthquake studies

/pdf/impact-of-gps-satellite-sky-distribution-fuwa0ndvmn.pdf

Impact of GPS satellite sky distribution.

With the rapid development of BeiDou system (BDS) and steady progress of Galileo system, the current GNSS (Global Navigation Satellite System) constellations consist of GPS, GLONASS, BeiDou and Galileo. The real signals from the four constellations have been available, which allows us to analyse and compare their measurement noises and multipath effects. In this study, a zero-baseline test is conducted using two ‘Trimble NetR9’ receivers to assess and compare the noises and multipath of measurements on multiple frequencies from the four satellite systems. The zero-baseline double difference approach is utilised to analyse the receiver noises. The code multipath combination and triple-frequency carrier phase combination approaches are exploited to analyse a comprehensive effect of the multipath and noises on the code and carrier phase measurements, respectively. Based on the analysis of the zero-baseline dataset, the results indicate that the code measurement noise levels range from 5 to 25 cm while the ca...

A comparative analysis of measurement noise and multipath for four constellations: GPS, BeiDou, GLONASS and Galileo

Precise point positioning (PPP), considered an alternative to differential positioning, is used in a significantly increased number of applications. Its integration into many practical areas is, however, slowed down by the long convergence time required in order to obtain cmlevel accuracy. This drawback is caused by the difficulty in fixing carrier-phase ambiguities to integers. As opposed to the differential mode, where many error sources are eliminated or greatly reduced, PPP has to properly account for all of them. Some of these error sources, such as code and phase biases, are complex to model as they tend to merge with the ambiguity parameters during the estimation process, leading to unsuccessful ambiguity resolution. This paper focuses on the receiver and satellite phase bias calibration required to recover the integer nature of carrier-phase ambiguities. A proper estimation of these biases would allow correcting the measurements and using the ambiguity resolution techniques developed for differential positioning. In this way, instantaneous cmlevel accuracy could be something conceivable even with a single GPS receiver, considering that the other error sources have been reduced to a significant level. The first step taken to achieve this objective is to clearly understand PPP’s functional model representing the code and phase measurements made by the GPS receiver. Special attention is paid to hardware delays, such as code and phase biases, which play a crucial role in the estimation process using undifferenced measurements. The impact of these quantities on some estimated parameters is described in order to have a better understanding of the concepts presented throughout this paper. In the second step, a receiver phase-bias calibration technique using a GPS signal simulator is introduced. A simulator has been used to generate errorless signals which are ideal to isolate the biases inherent to the receiver. Results show that this calibration process is complex due mainly to the correlation between the receiver clock and the ambiguity parameters. As such, between-satellite single differencing still seems to be the best way to eliminate receiver phase biases. The last part of this paper concerns satellite phase-bias calibration. To properly calibrate the satellite phase biases, the impact of code biases has to be carefully taken into consideration. For this purpose, an alternate widelane phase-bias calibration method is proposed and is shown to be coherent with PPP’s functional model.

/pdf/satellite-and-receiver-phase-bias-calibration-for-5el95sf2mu.pdf

Satellite and Receiver Phase Bias Calibration for Undifferenced Ambiguity Resolution

The single point positioning (SPP) mode has been widely used in many fields such as vehicle navigation, Geographic Information System and land surveying. For a long period, the SPP technology mainly relies on GPS system. With the recent revitalisation of the GLONASS constellation and two newly emerging constellations of BeiDou and Galileo, it is now feasible to investigate the performance of quad-constellation integrated SPP (QISPP) with GPS, GLONASS, BeiDou and Galileo measurements. As a satellite-based positioning technology, the QISPP is expected to improve the accuracy and availability of positioning solutions due to the increased number of visible satellites and the improved satellite sky distribution. In this study, a QISPP model is presented to simultaneously process observations from all four Global Navigation Satellite System (GNSS) constellations. Datasets collected at 47 globally distributed Multi-GNSS Experiment (MGEX) stations on two consecutive days and a kinematic experimental dataset are e...

Performance evaluation of single-frequency point positioning with GPS, GLONASS, BeiDou and Galileo

Time series analysis is an important part of geodetic and geodynamic studies, especially when continuous GPS observations are used to explore areas with a low rate of deformation. In this domain, having precise and robust tools for processing and analyzing position time series is a prerequisite. To meet this requirement, a new software package called GPS Interactive Time Series Analysis was developed using the MATLAB language. Along with calculating basic statistics and quality parameters such as mean and variance, the software is capable of importing and visualizing different time series formats, determining and removing jumps and outliers, interpolating data, and producing numerical and publication quality graphical outputs. Furthermore, bivariate statistical analysis (such as correlation coefficients, curvilinear and nonlinear regression), residual analysis, and spectral analysis (such as auto-spectrum, Lomb---Scargle spectrum, evolutionary power spectrum, and wavelet power spectrum) form the main analysis features of the software.

/pdf/gps-interactive-time-series-analysis-software-55lvqhwgvi.pdf

Rock Santerre

Papers

Impact of GPS satellite sky distribution.

A comparative analysis of measurement noise and multipath for four constellations: GPS, BeiDou, GLONASS and Galileo

Satellite and Receiver Phase Bias Calibration for Undifferenced Ambiguity Resolution

Performance evaluation of single-frequency point positioning with GPS, GLONASS, BeiDou and Galileo

GPS interactive time series analysis software