Abstract: A centimeter level survey system includes reference base station and rover GPS units connected by a radio data link. Each includes recorders for the storage of raw measurement information including range, phase, cycle counts and time information. The rover unit is typically moved to points of interest during a survey while the base remains over a fixed, and known location. Generally, the base antenna is located to optimize a clear view of the sky. The rover is subject to interruption of the radio data link from the primary reference station. During periods that the rover is initialized and in contact with the primary reference station base station over the radio data link, the rover provides real time centimeter level position solutions to a survey user, otherwise, the rover records its raw measurements in a file that begins with the last valid initialization information and that ends with any newly reestablished initialization information.

Abstract: A system embodiment of the present invention comprises a fixed and a roving pair of four-observable GPS receivers and a communication link between them for double differencing code and carrier measurements. Carrier phase integer ambiguities are resolved efficiently by searching the simultaneous narrow-lane intersections of both the L1 and L2 wave fronts propagated by the GPS satellites being tracked. External constraint information, such as elevation, is additionally used to speed up integer ambiguity resolution. Data between the reference station and the rover is communicated in compressed form at a regular interval, e.g., once a second at each epoch, and demi-measurements of carrier phase are obtained more frequently, e.g., ten times a second, and used to propagate solutions between epochs.

Abstract: A method for accurately determining the location of a pre-selected survey or construction mark, or for accurately identifying the survey position for a new mark with pre-selected location coordinates. A Satellite Positioning System (SPS), such as GPS or GLONASS, with at least two SPS stations (antennas and receiver/processors) is used to receive and analyze SPS signals from four or more SPS signal satellites. An SPS signal reference station is placed at a position with known location coordinates, which can be stationary or be known functions of time. An SPS signal roving station receives the location coordinates of the reference station and determines its own location coordinates relative to the reference station, using SPS differential positioning. The roving station is then moved to a pre-selected survey mark or position, either to locate that survey mark or to identify (by marking) a new survey position from pre-selected location coordinates.