GPS Measurement Corrections for Geophysicists

0317973Larson这笔赠款的资金将支持科罗拉多大学的一名研究生和有限的PI工资支持，为期两年，用于对各种商用双频大地GPS接收机的全球定位系统（GPS）伪距系统误差进行受控测量。 已知在可用双频GPS接收器之间的伪距中存在无法解释的和观察到的差异，这是从先前的零基线测量中得知的，在先前的零基线测量中，使用单个天线，随后将卫星信号分离并发送到两个或更多个GPS接收器进行冗余信号处理。 这种偏差很可能是由发射卫星、环境因素和定时所赋予的偏差的组合的结果，但也可能是由特定GPS接收机在当前可用GPS卫星频率中的一个或另一个上使用不同的可观测量所导致的。 由于国防部计划在现有的L2频率上增加另一个频率（L5）和一个额外的民用代码，未来的情况将变得更加复杂。 在这个项目中，PI和学生将进行进一步的零基线实验，以检查多个GPS接收机的伪距偏差在受控温度条件下使用热隔离室和更长的时间比已经取得了日期。 通过联合国志愿人员组织有限公司提供的几个全球定位系统接收器的测试结果GPS接收器池将与单个参考GPS接收器进行比较，该参考GPS接收器将在所有实验中保持运行。 这些结果将为高精度和超精度全球定位系统地壳运动估计以及改进全球定位系统导航提供改进的算法。 其他更广泛的影响包括提高了对美国国家科学基金会和其他政府机构（例如，南加州综合GPS网络、EarthScope板块边界天文台和国际GPS服务）。 ***

0317973LarsonFunds from this grant will support a graduate student at the University of Colorado and limited PI salary support over a two year period to conduct controlled measurements of global positioning system (GPS) pseudorange systematic errors for a variety of commercially available dual frequency geodetic GPS receivers. Unexplained and observed differences in the pseudoranges between available dual frequency GPS receivers are known to exist from previous zero-baseline measurements where a single antenna was used and the satellite signal was subsequently split and sent to two or more GPS receivers for redundant signal processing. Such biases are likely a result of a combination of biases imparted by the transmitting satellite, environmental factors and timing but also may result from specific GPS receivers use of differing observables on one or the other of the currently available GPS satellite frequencies. The situation will get more complicated in the future as the result of DOD plans to add another frequency (L5) and an additional civilian code on the existing L2 frequency. In this project, the PI and student will conduct further zero-baseline experiments to examine pseudorange biases of multiple GPS receivers under controlled temperature conditions using a thermal isolation chamber and for longer time periods than have been made to date. Results of tests of several GPS receivers available through the UNAVCO, Inc. GPS receiver pool will be compared to a single reference GPS receiver which will remain in operation for all experiments. The results should provide for improved algorithms for high accuracy and ultra precise GPS crustal motion estimates as well as improved GPS-navigation. Other broader impacts include improved confidence in sub-cm GPS estimates of position and baseline lengths for large GPS networks projects already funded by NSF and other government agencies (e.g., the southern California Integrated GPS network, the EarthScope Plate Boundary Observatory and the International GPS Service). ***