# Positioning Methods and the Use of Location and Activity Data in Forests
## 2 Types of Positioning Technologies
### Ultra Wideband and UHF/VHF Radio Telemetry  
UWB is a radio frequency channel operating at bandwidths greater than 500 megahertz (MHz) that is primarily used for communications, wireless sensor networks, positioning, and tracking [89; 90; 91]. Wide bandwidths allow UWB signals to transmit large amounts of data quickly at low power consumption. Due to their low frequency, UWB signals can more easily pass through obstacles, making UWB well-suited for forested environments [90; 91; 92]. Additionally, using a bi-cone antenna system, UWB can provide communications in remote areas with a relatively low loss of data [90]. Similar to GNSS, UWB positioning typically employs trilateration to estimate the location of a mobile tag (transmitter) based on the tag location relative to stationary anchor nodes (receivers) at known coordinates [91; 92; 93]. However, any of five general methods may be used for UWB positioning: angle of arrival (AOA), time of arrival (TOA), time difference of arrival (TDOA), received signal strength indication (RSSI), and hybrid algorithms [91; 93]. In AOA, anchor nodes triangulate a tag's position based on the direction of the received RF signal. For the time-stamp method of TOA, the anchor nodes use the propagation delay (signal travel time) and a known signal velocity to calculate their distances from the tag and then employ trilateration to estimate tag position (Figure 5). In another time-stamp method known as TDOA, anchors report signal receipt time to a location engine that compares the differences in arrival times and then estimates the location of the tag as the intersection of three hyperbolas (for two-dimensional positioning) [91; 93]. To employ the RSSI method, a path loss regression model is first developed to establish distance as a function of signal strength [92]. Then, anchor nodes use received signal strength to predict distance and in turn estimate tag location with trilateration. This method has relatively low accuracy and is used less frequently than time and angle-based methods [91; 92]. Lastly, hybrid algorithms combine methods to mitigate limitations of a single approach [91; 92; 93]. For example, AOA generally requires many more anchor nodes, while TDOA and TOA require precise synchronization among all anchor nodes. AOA and TDOA are frequently combined for improved positioning accuracy. UWB localization can typically achieve sub-meter accuracies (3-50 cm) even with consumer-grade units, though accuracy decreases in non-line-of-sight (NLOS) situations (see Table 1) [94; 77]. Signals are capable of traveling long distances (approximately 100 m) with line-of-sight (LOS) conditions [95]. In wildlife ecology and management, animal tracking via technology attached to animals has improved dramatically in the past several decades and can now give researchers excellent spatiotemporal data on an ever-widening array of terrestrial and aquatic species (for two recent reviews, see [PERSON] et al. [96] and [PERSON] et al. [97]). Traditional tracking approaches included (1) radio telemetry with VHF transmitters affixed to animals, which require manual or automated triangulation to record a location, or (2) pit tags and other passive location devices (e.g., geolocators for migratory birds [98]), in which locations are either recorded when animals approach powered antenna arrays or are stored on tags to be eventually recovered by researchers and downloaded. VHF and ultra high frequency (UHF) telemetry methods function essentially the same as UWB, and these frequencies have been used most commonly for research and management applications. New wildlife monitoring technologies based on GNSS location are rapidly replacing older telemetry techniques for medium-sized animals and larger terrestrial animals (e.g., birds greater than 250 g and ground-dwelling fauna greater than 15 g [97]) due to rapid, ongoing advances in miniaturization. Designs include collars, ear-tags, backpacks, glue-ons that adhere to shells, scales, or fur, and internally-implanted models [97].