Necessity

We have many questions about how to use GNSS RTK equipment to improve field accuracy. The most common method for RTK to achieve high accuracy is differential correction. In the measurement work, under normal circumstances, the data obtained by our RTK is obtained through automatic real-time correction. Of course, it is also possible to perform correction (ie post-processing) after collecting the measurements. Although GNSS satellites can calculate position with high accuracy, many errors are introduced between the signal leaving the satellite and hitting the receiver on the ground. Generally, corrections are effective because most sources of error (such as the atmosphere) are similar in a wide area. Differential correction can be applied to GNSS RTK receiver-rover measurements to eliminate most errors.

Principle

The principle is to install the base station on a known point and continuously collect GNSS data. At any given time, GNSS may tell the base station that its location is different from the actual location known to the base station. The result of the differential correction directly depends on the location of the base station used and the reference frame. Before starting a data collection project, it is important to understand the reference frame of the calibration source. This aspect applies to all forms of GNSS correction, including post-processing, RTK, VRS, etc. In most cases, this information should be available from the provider of the correction service.

Maintenance

The infrastructure of the calibration service base station is usually maintained by a surveyor or other geodetic survey organization. Today, most GPS receivers support differential correction through satellite-based augmentation systems (SBAS), such as the Wide Area Augmentation System (WAAS) in the United States. In this way, the reference position and coordinate system information is usually kept up to date with the latest benchmarks and implementations. This is usually in contrast to GIS recording systems, which use the same coordinate system for a longer period of time.

Learn more about RTK differential correction: https://www.satlab.com.se/product_category/gnss/

Tags RTK