Architecture and implementation of an affordable differential GPS system

In this paper we detail the implementation of a Differential GPS system using only low-cost GPS receivers. The nature of the errors generated by low-cost modules is investigated and contrasted against typical error models of traditional, commercial DGPS systems. It is found that the error profile unique to low-cost GPS modules leads to a system that offers particular advantage in the horizontal plane compared to uncorrected receivers and as such is especially suited for tasks such as mapping and field robotics. A particular incarnation is demonstrated on a mobile robot with experimental results from static and moving tests showing an accuracy in the plane on the order of one metre.