CORS means Continually Operating Reference Stations. The CORS network offers RTK differential correction information to be broadcast via the Internet and can be accessed through any Internet enabled device. In many cases, CORS is received through a cell signal. The correction info is sent to your rover and creates a “virtual base station” that offers RTK correction data. Therefore, using CORS means there is no need for a physical base station – you will not need to maintain your own base station or have access to a base station maintained by someone else. Instead, if you have a cell signal, you can access CORS to receive your RTK correction data.

CORS networks are usually run by a state’s Department of Transportation and are used for surveying and construction. However, these networks are being used more and more in the private sector, especially by precision farmers. Some receivers – such as Ag Leader’s ParaDyme™ automated steering system – use built-in cellular modems to connect to the CORS network, requiring no additional hardware. One major factor to take into consideration is the location of your fields and whether they allow for uninterrupted cell service.  In addition, not all GPS hardware is equipped to communicate with the CORS network.
RTK stands for Real-Time Kinematic. RTK correction is capable of sub-inch repeatable accuracy (from day to day, month to month, and year to year) and pass-to-pass accuracy (within the same day), and requires a base station in close proximity to your rover to transmit correction signals. A grower can purchase their own RTK base station, or they may have the option of purchasing a subscription to access an RTK tower network constructed by a retailer, cooperative, or other service provider. Whether you choose to maintain your own base station or access RTK towers through a service provider is another choice that depends on your operation. Several factors should be considered, including cost of maintenance vs. cost of subscription, interrupted access and your field locations, among other things.
A new way of receiving RTK differential correction signal is becoming more readily available through CORS networks.