Global Positioning System Survey data from 2015, Coachella Valley, Riverside County, California

Data collection: GPS measurements were taken at 24 geodetic monuments during September 27-October 2, 2015. The GPS surveys generally followed established guidelines (Zilkoski and others, 1997), except that the data were processed with single-baseline, rather than multi-baseline, software. GPS measurements were recorded at the monuments on at least 2 different days during 1-hour observation periods. Of the 24 geodetic monuments, 7 were network control stations—DUNE, COCH, DEEP, CAHU, PAIN, C101, and G70; GPS measurements were recorded at these seven stations on 3 additional days during 6.5-hour (or longer) observation periods. Data results: Determining the ellipsoid heights of the 24 geodetic monuments in the network involved 2 phases of least-squares adjustments. During the first phase of least-squares adjustments, horizontal coordinates and ellipsoid heights of the seven Coachella Valley network control monuments were determined by processing the GPS measurements taken at these monuments with simultaneous measurements at three continuous Global Positioning System (CGPS) stations (DHLG, PIN1, and WIDC) and by using precise satellite orbital data and accurate coordinates of the CGPS stations provided by the International GPS Service (IGS) and Scripps Orbit and Permanent Array Center (SOPAC), respectively. During the second phase of least-squares adjustments, the 7 network control monuments were fixed at the positions determined during the first phase, and the horizontal coordinates and ellipsoid heights for the other 17 monuments were calculated. The expected uncertainty of the ellipsoid heights was ±20 mm (±0.07 ft) at the 95-percent confidence level, which was determined using the maximum ellipsoid-height difference computed from 95 percent of the repeatedly observed baselines used in the adjustment. Software used for the baseline and least-squares adjustment computations for the 2015 survey was Trimble Business Center 2.81. Zilkoski, D.B., D’Onofrio, J.D., and Frakes, S.J., 1997, Guidelines for establishing GPS-derived ellipsoid heights, (Standards: 2 cm and 5 cm) version 4.3: Silver Spring, Md., National Geodetic Survey, 10 p., 3 appendices.

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  "010:12"
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  "geospatial"
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