GPS for Precision Farming: A Dense Network of Differential Reference Stations

This research proposes development of a low-cost, Wide Area Differential GPS (WADGPS) capability utilizing a dense network of multiple reference receivers (RR). The research will focus on determination of possible resolution with the dense network of reference receivers as applied to precision farming applications. "Resolution" is defined as repeatability vs. accuracy at a location once a Differential GPS (DGPS) spot measurement has been made with the dense network of RR. The improvement resolution offers potential innovative solutions to farmers faced with the need for increasing accuracy as a way of reducing labor, chemical and fertilizer costs and, at the same time, providing documentation for new regulatory requirements. If sufficient resolution precision can be achieved, it can also provide the basis for guidance. GPS location measurement to 30 meters is possible in native mode and two meter accuracy is achievable over limited distance with DGPS, using a single RR. GPS signals are affected by atmospheric signal propagation effects, satellite orbital erros, receiver noise, clock synchronization, etc. The proposed research will determine resolution improvement with nullification of these errors, using correction data provided by a dense network of multiple RR. The attainable precision will be mapped against agriculture requirements for guidance (e.g., tilling) and application systems (e.g., fertilizer, insecticide, herbicide).