Approved for public release; distribution is unlimited / Measurements of a 1230-km baseline were made during an eight-week period in the fall of 1987 using Trimble 4000SX single-frequency, five channel Global Positioning System (GPS) receivers. Twenty-eight days of carrier phase data were processed using correlated triple differences with fixed satellite orbits, the broadcast ephemerides, a modified Hopfield tropospheric model, and without ionospheric correction to determine the accuracies and precisions of the slope distance and baseline components. The data were processed in ever increasing observing sessions to determine the optimized observation periods required to achieve various orders of geodetic accuracies. The accuracies of the slope distances were better than 1.0 ppm for any observing period. The day-to-day repeatabilities of the slope distance measurements were better than 1.0 ppm (2) sigma after 20 minutes of observations. Accuracies and repeat-abilities (2 sigma) of the baseline components were better than 10.0 ppm after 20 minutes of observations. The correlated triple difference results were on the order of previous GPS surveys that used higher resolution differencing or external timing aids. Discussions include the effect of ephemeris, tropospheric and ionospheric errors, and dilution of precision. Observation periods and mean slope distance errors were reduced when observations started close to and included the infinite peak of the Position Dilution of Precision (PDOP). The smallest variances were associated with observations about the infinite PDOP peak / http://archive.org/details/optimizedobserva00bouc / Lieutenant, United States Navy