# Positioning Methods and the Use of Location and Activity Data in Forests
## 2 Types of Positioning Technologies
### GNSS with Two-Way Satellite Communication  
Where forestry and wildland fire activities occur in proximity to the built environment, it is possible to relay location coordinates to others via mobile data transfer using conventional cellular communication and Internet connectivity. Google location services on Android-based mobile devices, for example, make it possible to share the location of one's smartphone with other individuals over the Internet [72]. Positioning of devices in the built environment where cellular coverage is available can be done with high accuracy due to cellular tower trilateration, map-matching, and other methods integrated into phones or apps that improve on or substitute for GNSS-based positioning [73; 74; 75; 76; 77]. However, forestry and wildland fire management activities often occur in areas where cellular coverage is poor; thus, methods that rely on cellular connectivity are primarily useful in portions of the Wildland Urban Interface (WUI). Even in these areas, it is common for cellular connectivity to be lost or overloaded during large fires and other natural disasters [78]. Satellite communications technology allows for messaging and voice communications independent of cellular infrastructure [79; 80]. Over the last decade, multiple devices have been marketed for forestry and recreation that provide emergency location services to individuals working or recreating in remote environments [20; 81; 80]. These include, for example, SPOT(tm) receivers and Garmin inReach(tm) two-way messaging devices (Figure 2, panel B). GNSS coordinates are transmitted along with automated or custom text messages to the urban environment via dedicated data communication satellites [80; 81]. Both SPOT and inReach devices can send a user's GNSS location, messages indicating safety status, and alerts to contact emergency services [81; 82]. Depending on the model, certain SPOT receivers only allow for pre-loaded messages and one-way communication while other SPOT receivers and all inReach devices allow for both preset and custom messages as well as two-way messaging [82; 83]. SPOT receivers operate on the Globalstar satellite network while inReach devices operate on the Iridium satellite network [82; 83]. Iridium is being replaced with the Iridium NEXT constellation that will provide broader coverage and support more bandwidth and higher speeds [84]. Insofar as  
Figure 3: In a Satellite-Based Augmentation System (SBAS) (**left** panel), reference stations located at precisely-surveyed points receive and forward their GNSS signals to the master station, which then calculates corrections. These corrections are sent to SBAS satellites, which in turn broadcast correction messages to the end user. In a Ground-Based Augmentation System (GBAS), such as real-time kinematic (RTK) positioning (**right** panel), a base (reference) station at a known location and a mobile rover both receive pseudorange and carrier phase measurements from similar satellites. Common errors between the units are estimated and correction data from the base station is transmitted to the rover for use in real-time or is utilized in post processing. multiple individuals may carry devices (e.g., wildland fire crew, recreation crews, wildlife technicians), emergency location and messaging devices can form a simple multi-unit network. However, location information is primarily intended for outside supervisors or support resources in an urban environment elsewhere [80; 81]. As of 2018, the frequency with which locations can be transmitted using paid-monthly services using Garmin inReach is one location every two minutes [82]. The fastest tracking interval for SPOT receivers at the time of preparing this manuscript is every 2.5 min [83]. Many consumer-grade GNSS transponder devices are available for less than US $100 to facilitate position observation independently from voice or text communication.