Bringing GPS into harsh environments for fully automated deformation monitoring     

Jason Bond  Adam Chrzanowski  Don Kim 《GPS Solutions》2008,12(1):1-11

Engineering projects that require deformation monitoring frequently utilize geodetic sensors to measure displacements of target points located in the deformation zone. In situations where control stations and targets are separated by a kilometer or more, GPS can offer higher precision position updates at more frequent intervals than can normally be achieved using total station technology. For large-scale deformation projects requiring the highest precision, it is therefore advisable to use a combination of the two sensors. In response to the need for high precision, continuous GPS position updates in harsh deformation monitoring environments, a software has been developed that employs triple-differenced carrier-phase measurements in a delayed-state Kalman filter. Two data sets were analyzed to test the capabilities of the software. In the first test, a GPS antenna was displaced using a translation stage to mimic slow deformation. In the second test, data collected at a large open pit mine were processed. It was shown that the delayed-state Kalman filter developed could detect millimeter-level displacements of a GPS antenna. The actual precision attained depends upon the amount of process noise infused at each epoch to accommodate the antenna displacements. Higher process noise values result in quicker detection times, but at the same time increase the noise in the solutions. A slow, 25 mm displacement was detected within 30 min of the full displacement with sigma values in E, N and U of ±10 mm or better. The same displacement could also be detected in less than 5 h with sigma values in E, N and U of ±5 mm or better. The software works best for detecting long period deformations (e.g., 20 mm per day or less) for which sigma values of 1–2 mm are attained in all three solution components. It was also shown that the triple-differenced carrier-phase observation can be used to significantly reduce the effects of residual tropospheric delay that would normally plague double-differenced observations in harsh GPS environments.

Don KimEmail:

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Spin rate estimation of sounding rockets using GPS wind-up   总被引：2，自引：1，他引：1  

M. García-Fernández  M. Markgraf  O. Montenbruck 《GPS Solutions》2008,12(3):155-161

Carrier phase wind-up is a well-known effect that arises from the relative rotation between a transmitting and receiving antenna. In GPS measurements at L1 frequency, this effect translates into an error of 19.029 cm per full relative rotation of antennas. Since this effect is independent of the satellite elevation for pure rotation about the antenna boresight axis, it is usually absorbed by the clock estimation in navigation algorithms. Therefore, the impact of wind-up is usually neglected for applications that do not require accuracies to the cm level like RTK. However, in receiving platforms with high rotation rate, the accumulated wind-up value can be important and actually be larger than receiver noise or even ionospheric variations. Therefore, in such scenarios, the wind-up contribution can be isolated and used as a source of information to compute the spin rate of such platforms using an appropriate combination of GPS observables. This work shows some results of a coarse, yet simple, approach to monitor the rotation angle and spin-rate of spin stabilized sounding rockets flown by DLR.  相似文献   

Using GPS multipath to measure soil moisture fluctuations: initial results   总被引：13，自引：2，他引：11  

Kristine M. Larson  Eric E. Small  Ethan Gutmann  Andria Bilich  Penina Axelrad  John Braun 《GPS Solutions》2008,12(3):173-177

Measurements of soil moisture are important for studies of climate and weather forecasting, flood prediction, and aquifer recharge studies. Although soil moisture measurement networks exist, most are sparsely distributed and lack standardized instrumentation. Measurements of soil moisture from satellites have extremely large spatial footprints (40–60 km). A methodology is described here that uses existing networks of continuously-operating GPS receivers to measure soil moisture fluctuations. In this technique, incoming signals are reflected off and attenuated by the ground before reception by the GPS receiver. These multipath reflections directly affect signal-to-noise ratio (SNR) data routinely collected by GPS receivers, creating amplitude variations that are a function of ground reflectivity and therefore soil moisture content. After describing this technique, multipath reflection amplitudes at a GPS site in Tashkent, Uzbekistan are compared to estimates of soil moisture from the Noah land surface model. Although the GPS multipath amplitudes and the land surface model are uncalibrated, over the 70-day period studied, they both rise sharply following each rainfall event and slowly decrease over a period of ∼10 days.  相似文献   

GPS signal acquisition using the repeatability of successive code phase measurements     

Zhen Zhu  Frank van Graas  Janusz Starzyk 《GPS Solutions》2008,12(1):43-53

This paper introduces a new method for GPS signal acquisition, which is based on the repeatability of successive code phase measurements and the M-of-N search algorithm. The performance of the proposed method in terms of probability of signal detection is similar to that of traditional methods, except that the calculation of the probability of detection does not rely on the noise distribution or the Carrier-to-Noise ratio (C/N₀). The code phase repeatability-based method is presented along with equations for probability of detection and probability of false detection. If the distribution of the noise is known, it also provides an estimate of the C/N₀. The proposed method is illustrated for coherent and non-coherent acquisition and C/N₀ estimation.  相似文献   

公交车站台智能显示牌系统设计与实现——以南充市的一个站台为例   总被引：1，自引：0，他引：1  

郭小龙 《测绘科学》2008,33(6):179-181

介绍了一种基于GIS/GPS/GSM技术的实时显示公交车运动状态和时间的电子显示牌设计方案。以南充市为例,在利用GPS系统对车辆精确定位的基础上,采用GSM无线通讯网关实现消息的传输,并在电子地图上实时的显示出公交车辆的位置、状态和各路公交车到达客人所在目的站点所需用的时间,方便人们更有效快捷地选择交通工具。本文重点分析了系统的各组成部分的功能和实现方式,最后采用VC++6.0和MapXtreme2004开发实现了该系统。  相似文献   

提高GPS RTK拟合高程精度的试验研究     

刘常弘  曹星星 《地理空间信息》2008,6(5):99-101

通过对工程实例的分析、总结,提出了在小范围平坦地区提高GPSRTK拟合高程的精度的一种方法,该方法在生产中具有一定的实用价值。  相似文献   

Experiment in Improving the Fitting Height Precision of GPS RTK     

LIU Changhong  CAO Xingxing 《地理空间信息》2008,6(5)

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GPS控制网环检验程序的设计     

洪伟  佟书泉 《地理空间信息》2008,6(5):74-76

在GPS控制测量中,环检验是个不可或缺的步骤,其目的在于及时发现粗差,控制整网的精度。本文通过设计一个环检验程序,从算法角度讨论了手工检验和自动检验的具体实现,并详细介绍了针对复杂网形控制网构环算法的优化,保证了程序的可靠性和稳健性。  相似文献   

数字测图技术在阜新市地理数据库更新中的应用   总被引：1，自引：0，他引：1  

陈文慧  陈冬晖  王占新 《测绘与空间地理信息》2008,31(1):46-48

采用GPS和全站仪联合作业的数字测图方式进行了外业快速数据采集。并利用南方CASS软件对数据进行内业成图工作,最后利用大型的地理信息系统软件ArcGIS进行地理数据的入库,从而实现了阜新市区地理数据库的更新,此方式具有速度快、效率高和精度高等优点,可以借鉴到同类的地区。  相似文献   

GPS伪卫星的组合定位技术及其误差分析     

杨荣华  花向红  吴文英  孙小芳 《地理空间信息》2008,6(4):48-50

介绍了GPS伪卫星组合定位的观测模型,详细论述了GPS伪卫星组合定位中存在的误差源,并对各误差源的消除方法进行了分析。  相似文献