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Although these parameters limit the usefulness of the RTK technique for general navigation, the technique is perfectly suited to roles like surveying. In this case, the base station is located at a known surveyed location, often a benchmark, and the mobile units can then produce a highly accurate map by taking fixes relative to that point.
It is the most accurate technique currently available to determine the geocentric position of an Earth satellite, allowing for the precise calibration of radar altimeters and separation of long-term instrumentation drift from secular changes in ocean surface topography. Satellite laser ranging contributes to the definition of the international ...
In surveying, free stationing (also known as resection) is a method of determining a location of one unknown point in relation to known points. [1] There is a zero point of reference called a total station. The instrument can be freely positioned so that all survey points are at a suitable sight from the instrument.
Position resection and intersection are methods for determining an unknown geographic position (position finding) by measuring angles with respect to known positions.In resection, the one point with unknown coordinates is occupied and sightings are taken to the known points; in intersection, the two points with known coordinates are occupied and sightings are taken to the unknown point.
Precise positioning is increasingly used in the fields including robotics, autonomous navigation, agriculture, construction, and mining. [2]The major weaknesses of PPP, compared with conventional consumer GNSS methods, are that it takes more processing power, it requires an outside ephemeris correction stream, and it takes some time (up to tens of minutes) to converge to full accuracy.
RTK surveying uses one static antenna and one roving antenna. The static antenna tracks changes in the satellite positions and atmospheric conditions. The surveyor uses the roving antenna to measure the points needed for the survey. The two antennas use a radio link that allows the static antenna to send corrections to the roving antenna.
Total stations are the primary survey instrument used in mining surveying. A total station is used to record the absolute location of the tunnel walls, ceilings (backs), and floors, as the drifts of an underground mine are driven. The recorded data are then downloaded into a CAD program and compared to the designed layout of the tunnel.
DGPS Reference Station (choke ring antenna)A reference station calculates differential corrections for its own location and time. Users may be up to 200 nautical miles (370 km) from the station, however, and some of the compensated errors vary with space: specifically, satellite ephemeris errors and those introduced by ionospheric and tropospheric distortions.