GPS mass-market receivers for precise farming

The use of Global Navigation Satellite Systems (GNSS) can help farmers become more efficient, reduce their use of chemicals, and increase crop yields. By increasing the accuracy, availability, reliability and continuity of satellite signals, the use of some augmentations systems (such as WAAS or EGNOS or other private systems) will remove some of the barriers to the adoption of precision agriculture, also not only considering geodetic receivers and complex systems of navigation. The goal of this work is to show how it is possible to consider both mass-market receivers and antennas to obtain centimetrical accuracies, useful for many precise farming applications. As it is possible to find in bibliography, the accuracy of real-time positioning depends mainly on the type of receiver (whether it is single frequency or low-cost) and antenna (whether it is patch, mass-market or geodetic) used. Some different receivers and antennas were tested and some results can be shown, not to analyze what receiver or antenna is the best but in order to analyze the state of the art of these type of instruments. The NRTK experiences have been conducted using mass-market receivers (mainly u-blox) within the Regione Piemonte network of permanent stations. Good results have been obtained: in fact, despite a single frequency instrument is used, the horizontal and vertical components have centimetrical level of accuracy. The maximum 2D error in the case of `fix' positioning is always less than 5 cm, precision required in many applications of precise farming, such as to individuate livestock positioning and fencing or for crop cultivation (e.g. cereals) and other low-accuracy operations (fertilising and reaping). Practical experiences have demonstrated the value of precise navigation and guidance technologies to increase yield and efficiency of agricolture operations and we want to show it in this paper. Under this condition, mass market sensors could be a valid instruments for a large part of surveying applications related to precise farming.