Differential correction for GNSS systems may be transmitted through which method?

Differential correction for GNSS (Global Navigation Satellite System) systems enhances the accuracy of position data by using reference stations that compare the GNSS data with known fixed positions. This correction data can significantly improve the accuracy of GNSS readings, which is especially important in dynamic positioning applications.

The correct choice is that differential corrections can be transmitted through any of the mentioned methods. This includes online services, satellite signals, and base stations.

1. Online Services: These services, often called real-time kinematic (RTK) or real-time differential GPS (RDGPS), provide corrections via the internet. Data is sent from a network of base stations to users who are connected online, making it possible to obtain corrections in real-time over a wide area.

2. Satellite Signals: Some GNSS systems employ satellites to relay correction information directly to GNSS receivers. This method allows users to receive differential corrections without needing to rely on terrestrial infrastructure.

3. Base Stations: A traditional method involves using a fixed base station that transmits corrections to roving GNSS units in its vicinity. This is often done using radio signals or other communication systems, and is widely utilized in various applications requiring high positional accuracy.

Because all these methods are valid for transmitting differential