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RTK Mapping 8
While the RTK system computes very precise GPS positions and
displays reliable precision estimates, these positions are only accurate
when compared to each other. To achieve high levels of absolute
accuracy (when comparing with existing data sources), it is important
to calibrate the data against existing good quality control points. An
accurate location for the base station is also important, as are accurate
heights for both the base and roving receiver antennas.
8.2.1 Real-Time Kinematic Data Collection
RTK data collection is a combination of specialized GPS and radiomodem
equipment that has been utilized by the land survey
community for precisely defining positions on or near the earth’s
surface. The RTK system, in conjunction with appropriate surveying
techniques, is designed to derive positions in the field to centimeter
levels of accuracy for both the horizontal and vertical components of a
coordinate.
RTK operates using relative measurement techniques, in the same way
that differential GPS (DGPS) operates. There is a base station (also
referred to as a reference station) and a roving receiver. The position
of the rover is determined relative to the base station (illustrated in
Figure 8.1). The base station is set up as a stationary receiver over a
known or assumed reference point for the duration of the data
collection session. (A known reference mark is generally a
well-defined survey mark in terms of a local or national coordinate
system.) The roving receiver is moved to features that are to be
collected or updated.
TSC1 Asset Surveyor Operation Manual 187