User Guidelines for Single Base Real Time GNSS Positioning. Version 2.1.

摘要

These user guidelines are intended to provide a practical method to obtain consistent, accurate three-dimensional positions using classical, single base real-time (RT) techniques (see Chapter V.). However, in addition to these best methods, and due to the plethora of variables associated with RT positioning, this document is meant to be a source for pertinent background information that the competent RT user should digest and keep in mind when performing high-accuracy positioning. Due to the rapidly changing environment of Global Navigation Satellite System (GNSS) positioning, it is understood that this documentation will be dynamic and would be best served to remain in digital form. Improvements to GNSS hardware and software, increased wireless communication capabilities, new signals, and additional satellite constellations in production or planned will yield significantly increased capabilities in easier, faster and more accurate data for the RT positioning world in the near future. These guidelines are not meant to exclude other accepted practices users have found to produce accurate results, but will augment the basic knowledge base to increase confidence in RT positioning. Classical (single base) Real-Time Kinematic (RTK) positioning or RT positioning as commonly shortened, is a powerful application employing GNSS technology to produce and collect three-dimensional (3-D) positions relative to a fixed (stationary) base station with expected relative accuracies in each coordinate component on the order of a centimeter, using minimal epochs of data collection. Baseline vectors are produced from the antenna phase center (APC) of a stationary base receiver to the APC of the rover antenna using the Earth-Centered, Earth-Fixed (ECEF) X,Y,Z Cartesian coordinates of the World Geodetic System 1984 (WGS 84) datum, the reference system in which the Department of Defense (DoD) Navstar Global Positioning System (GPS) system broadcast orbits are realized (differential X,Y,Z vectors in other reference frames would be possible if different orbits were used). Some current technology may also incorporate the Russian Federation Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) constellation into the computations, whose orbits are defined in the Parametry Zemli 1990 (Parameters of the Earth 1990- PZ 90.02) datum. The coordinates of the point of interest at the rover position are then obtained by adding the vector (as a difference in Cartesian coordinates) to the station coordinates of the base antenna, and applying the antenna height above the base station mark and also the height of the rover pole. Usually, the antenna reference point (ARP) is used as a fixed vertical reference.