The influence of the number of satellites on the accuracy of RTK GPS positions

Lemmon, Timothy R.; Gerdan, George P.

doi:10.1080/00050326.1999.10441905

Cited by 12 publications

(9 citation statements)

References 5 publications

(1 reference statement)

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“…Conventional RTK-GPS manufacturer specifications cite nominal accuracy for their dual-frequency GPS systems that are on the order of ±1 cm+2 ppm for hori-zontal position measurements and ±2 cm+2 ppm for vertical position measurements; independent verification of these accuracy levels has shown that they are generally correct within reasonable survey distances from the base station unit (e.g., Lemmon and Gerdan 1999). Many vendors also indicate that the more satellites that are being received, the better the measurement accuracy will be, which seems logical given the general operating principles of GPS technology.…”

Section: Determination Of Lift Thicknessesmentioning

confidence: 99%

“…Many vendors also indicate that the more satellites that are being received, the better the measurement accuracy will be, which seems logical given the general operating principles of GPS technology. Interestingly, Lemmon and Gerdan (1999) reported that, for field surveys conducted where the GPS satellite counts ranged between 5 and 9, an increase in satellites made no significant contribution to the accuracy of the RTK positions (although the reliability of the ambiguity resolution process did improve).…”

Section: Determination Of Lift Thicknessesmentioning

confidence: 99%

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Monitoring Field Lift Thickness Using Compaction Equipment Instrumented with Global Positioning System (GPS) Technology

Meehan

Khosravi

Cacciola

2013

Geotechnical Testing Journal

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When constructing earthen embankments, it is essential that the soil be placed and spread in uniform lifts prior to compaction. To ensure that the resulting soil lifts are evenly compacted, typical compaction specification approaches place restrictions on the thickness that is acceptable for each soil lift. In current practice, it can be extremely difficult for a field inspector to verify that lift thickness requirements are being met when soil is being placed and spread over a large area, without the use of frequent surveying (which adds both costs and delays to earthwork projects). Recent advances in compaction control include the development of continuous compaction control (CCC) and intelligent compaction (IC) systems, which provide real-time monitoring and feedback about the operation and performance of soil compaction. Typically, CCC and IC compaction equipment is outfitted with a real-time kinematic global positioning system (RTK-GPS) that monitors and records the position of the compacter as the soil lift is being compacted. This paper suggests that geotechnical engineers use field RTK-GPS measurements that are made by CCC or IC equipment to monitor and control the thickness of compacted soil lifts. Data collected from a full-scale field study is used to illustrate the practical issues with using GPS measurements for field monitoring of lift thickness during construction of a roadway embankment, such as varying roller position from lift-to-lift and the measurement uncertainty associated with RTK-GPS measurement data. The use of both simple and sophisticated spatial analysis techniques are explored for interpolating measured field elevation data onto a uniform grid for lift thickness assessment. The resulting methodology that is presented can be utilized to build spatial maps of compacted soil lift thickness, a process that can be used to great benefit by field engineers who are trying to ensure the quality of compacted soil lifts.

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Section: Determination Of Lift Thicknessesmentioning

confidence: 99%

Section: Determination Of Lift Thicknessesmentioning

confidence: 99%

Monitoring Field Lift Thickness Using Compaction Equipment Instrumented with Global Positioning System (GPS) Technology

Meehan

Khosravi

Cacciola

2013

Geotechnical Testing Journal

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“…Method 2: 20 distinct ground objects were selected within the power line corridor, whose 3D ground coordinates were measured in the field by GPS RTK. The accuracy of planimetry and elevation both reached the centimeter level in the ground [18], so were regarded as 'ground trues'. The 3D coordinates obtained in the stereo measuring environment were compared with these true values one by one to evaluate the accuracy of the automatically extracted dense 3D point cloud.…”

Section: Detection Of Obstacles In the Power Line Corridormentioning

confidence: 99%

UAV Low Altitude Photogrammetry for Power Line Inspection

Zhang

Yuan

Fang

et al. 2017

IJGI

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When the distance between an obstacle and a power line is less than the discharge distance, a discharge arc can be generated, resulting in the interruption of power supplies. Therefore, regular safety inspections are necessary to ensure the safe operation of power grids. Tall vegetation and buildings are the key factors threatening the safe operation of extra high voltage transmission lines within a power line corridor. Manual or laser intensity direction and ranging (LiDAR) based inspections are time consuming and expensive. To make safety inspections more efficient and flexible, a low-altitude unmanned aerial vehicle (UAV) remote-sensing platform, equipped with an optical digital camera, was used to inspect power line corridors. We propose a semi-patch matching algorithm based on epipolar constraints, using both the correlation coefficient (CC) and the shape of its curve to extract three dimensional (3D) point clouds for a power line corridor. We use a stereo image pair from inter-strip to improve power line measurement accuracy by transforming the power line direction to an approximately perpendicular to epipolar line. The distance between the power lines and the 3D point cloud is taken as a criterion for locating obstacles within the power line corridor automatically. Experimental results show that our proposed method is a reliable, cost effective, and applicable way for practical power line inspection and can locate obstacles within the power line corridor with accuracy better than ±0.5 m.

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“…using a different satellite constellation with >2 hour time difference), then a second short occupation should improve the point accuracies, which will in turn improve the reliability through an independent occupation. If the two occupations show good coordinate agreement, both results can be combined to determine the final coordinate (Mowafy 1997), Hoffmann 2000), (Lemmon 1999), (Thales navigation 2002), (Van Diggelen 1997). The limitations of the RTK system include the following:…”

Section: Real Time Kinematic Gps (Rtk Gps)mentioning

confidence: 99%