Single-Beam derived bathymetric contours of Lake Okeechobee, Florida (2001) in Esri shapefile format

The GPS antenna and receiver acquisition configuration used at the reference station was duplicated on the survey vessel (rover). The base receiver and the rover receiver record their positions concurrently at 1 Hz recording intervals throughout the survey. All processed measurements are referenced to the base station coordinates.
GPS base or differential reference stations were operated within approximately 15 to 20 km of the survey area. Ten new, temporary ground-control points or benchmarks (surveyed to within 1 cm to 2 cm accuracy) were established throughout the study area for use as reference receiver sites using standard benchmarks procedures. The new benchmarks were surveyed using Ashtech Z-12, 12 channel dual-frequency GPS receivers. Full-phase carrier data were recorded on each occupied benchmark in Ashtech proprietary BIN format with daily occupations ranging from 6 to 12 hours. BIN files were then converted to RINEX-2 format for position processing.
All static base station GPS sessions were submitted for processing to the online OPUS, GIPSY, and SCOUT system software. The computed base location results were entered into a spreadsheet to compute one final positional coordinate and error analysis for that base location. The final positional coordinate (latitude, longitude, and ellipsoid height) is the weighted average of all GPS sessions. For each GPS session, the weighted average was calculated from the total session time in seconds; therefore, longer GPS occupation times held more value than shorter occupation times. Results were computed relative to ITRF00 coordinate system. The established geodetic reference frame for the project was WGS84. Therefore, final reference coordinates used to process the rover data were transformed from ITRF00 to WGS84 using National Oceanic and Atmospheric Administration/National Geodetic Survey(NOAA/NGS) HTDP software v2.1.
OPUS, GIPSY, and SCOUT results provide an error measurement for each daily solution. Applying these error measurements, the vertical accuracy of the base station is estimated to be 0.04 (m) root mean squared (RMS).
The kinematic (rover) trajectories were processed using PNAV v2.0, by Ashtech, Inc. A vertical error measurement, RMS, is computed for each epoch. The vertical trajectory errors varied between 0 and 0.08(m).
The combined vertical error from base station coordinate solutions and rover trajectories range from 0 to 0.14 (m), with the average approximately 0.08 (m).