Locata: A new positioning technology for classically difficult GNSS environments

Despite the popularity and maturity of RTK GPS (GNSS), acceptable performance is heavily dependent on a relatively unobstructed sky-view, where there are at least five satellites with good geometry available, and on the reliability of the wireless data link used for differential corrections. In so-called “difficult” environments where satellite obstruction is common, such as open-pit mining and urban environments, the limitations of satellite based technologies quickly become apparent with disappointing performance. Locata’s solution to these “difficult” environments is to deploy a network of terrestrially-based transceivers that transmit ranging signals. For terrestrial-based RF systems severe multipath in the form of signal fading is a serious issue. In this paper details of Locata’s current system are discussed, employing signal spatial diversity to address multipath fading. It is shown that in a moderate signal fading environment the Locata technology can provide cm-level accurate RTK position solutions 100% of the time.