What type of inaccuracies do error correction methods in GNSS address?

Error correction methods in GNSS (Global Navigation Satellite System) are designed specifically to address inaccuracies that occur in satellite signals. These methods are crucial because the signals transmitted by satellites can be affected by various factors such as atmospheric disturbances, satellite clock errors, and multipath effects, where signals bounce off surfaces before reaching the receiver.

To enhance the accuracy of positioning, techniques such as Differential GPS (DGPS), Real Time Kinematic (RTK) positioning, and Satellite-Based Augmentation Systems (SBAS) are employed. These systems work by comparing the signal received by a reference station, which is located at a known position, to the signal received by the user's GNSS receiver. By identifying and correcting the discrepancies, accurate positioning information can be provided.

The other options pertain to types of inaccuracies that are not primarily addressed by GNSS error correction methods. For instance, human errors or issues related to environmental conditions such as obstructions can affect GNSS performance but aren't directly corrected through error correction techniques focused on satellite signals. Device calibration inaccuracies also fall outside the scope of GNSS error correction, as these are typically managed through other calibration procedures.