The key issue relating to GPS is its accuracy. For agricultural applications differential GPS must be used. This requires a source of correction data which may or may not require yearly licensing fees. The accuracy of the positioning depends on many factors including the quality of the receivers, the quality of the correction source, the distance from the correction source, weather conditions, obstacles and other factors. Once the yield data has been stored in portable memory it can be downloaded into a personal computer.
Appropriate software is needed to display and manipulate the data in useful ways.
Less expensive systems allow data to be shown in tabular form and in simple yield maps. This software is relatively expensive and difficult to use. The data analysis stage can be further broken down into at least two steps. Data manipulation involves displaying the data to minimize errors or insignificant data and to display it in ways that are meaningful. The actual analysis stage involves the application of agronomic knowledge and experience to make management decisions.