Farming is a complex business which involves managing variables such as weather, soil and crop inputs to ultimately maximize yield and minimize waste and cost. As population growth continues to increase, so do demands on our food supply. Today, more than ever, farmers rely on technology to manage their fields in order to optimize productivity.
Global Navigation Satellite Systems (GNSS) integrate with agricultural machinery to serve a critical role in precision agriculture. At a basic level, these systems help farmers keep rows straight and ensure that the spacing of seed and application of other inputs like fertilizers, herbicides and fungicides are applied with minimal gaps or overlaps. The benefits of high accuracy GNSS positioning are well known throughout the agriculture community and contribute to the optimization of land use and resource application.
Predictive analytical software, for example, allows farmers to identify zones of variability within their fields so that they can be managed appropriately at the micro level. A farmer can increase seed density in a particular zone where water and crop nutrients may be more plentiful, while reducing seed density in another zone that has fewer resources to sustain plant growth—all based on GNSS positioning.
Farmers around the world increasingly rely on higher accuracy positioning systems to work more efficiently in their fields. Stand-alone GNSS data needs additional corrections to reduce system errors and deliver higher positioning accuracies. Early on, these accuracies were achieved using either Real-Time Kinematic (RTK) or Satellite Based Augmentation Systems (SBAS) like the GPS Wide Area Augmentation System (WAAS). However, in recent years, there has been a rising trend in precision agriculture towards the use of Precise Point Positioning (PPP) solutions to meet this demand. PPP is a positioning method which provides better accuracy than WAAS and simplifies equipment requirements when compared to RTK, where separate communication links are required. While PPP is not a new idea, recent receiver technology and GNSS advancements have significantly improved the performance of PPP solutions, making this a viable alternative to RTK for many precision agriculture users.
When employing PPP, the error sources are mitigated by combining satellite orbit and clock correction data with error modeling in the receiver, resulting in sub-decimetre accuracy. The GNSS hardware requirements for a PPP solution are limited to only a single receiver on the machine, using globally applicable corrections that provide the same performance anywhere in the world. Correction data is delivered via satellite to the same receiver used for GNSS signal tracking and does not rely on proximity to ground network infrastructure.
PPP performance has been steadily improving; in some cases rivaling the performance of RTK based systems that provide centimetre-level accuracy. NovAtel CORRECT™ proprietary algorithms on NovAtel’s OEM6® GNSS receivers were developed to optimize the performance achieved using TerraStar-C correction data. Utilizing data from both GPS and GLONASS satellite systems, TerraStar-C corrections combined with NovAtel CORRECT’s error modeling, enables positioning accuracy as good as four centimetres—more than sufficient in most cases for planting crops such as corn and soybeans, in addition to other precision agriculture applications. NovAtel CORRECT also optimizes other key performance criteria, including initial solution convergence and re-convergence times.
As mentioned previously, machine guidance systems using NovAtel CORRECT with PPP do not require local base-station infrastructure, including cellular modem, Wi-Fi, or other radio data links. Fewer hardware requirements can translate into significant investment savings for the agriculture producer. The savings are even greater in remote areas, where local base stations, cellular services and Internet connectivity required for RTK operation might not exist. While RTK still offers premium accuracy and immediate solution convergence, the combination of minimal equipment needs and a globally accessible solution make PPP a complimentary alternative to RTK for many precision agriculture applications.
By partnering with TerraStar for its PPP offering, NovAtel customers benefit from the reliability and quality of an established service. TerraStar infrastructure and data products are built on 20 years of expertise and backed by fully redundant and independent data centers with delivery of data over multiple satellites. In addition, TerraStar provides service flexibility that can help farmers manage their operating costs throughout the growing seasons. Typical subscriptions cover one, three, six, or 12 months which means a farmer who requires a high level of accuracy for spring planting only, does not have to subscribe to the service for a full year.