Comparison of Ultrasonic Positioning Systems Under Various Environmental Challenges

Innovation in ultrasonic telemetry technologies is allowing researchers to gather detailed information on the localized movement of focal species. It is important for researchers to understand the relative strengths and weaknesses of available technologies to select the system most appropriate for a study. To compare the performance of two positioning systems produced by VEMCO, the VR2W Positioning System (VPS) and Radio Acoustic Positioning system (VRAP), we deployed both in tandem at three sites which varied in the challenges posed by local environmental conditions. Each array was designed to maximize performance, and thus deployment details varied by site. The sites included a Californian kelp forest, a littoral freshwater habitat in the San Francisco Estuary, and a section of the Sacramento River. We compared the systems’ ability to accurately position tags, and the frequency of tag positioning. We found that unfiltered data from the VPS was more accurate at two sites, but the system demonstrating a superior positioning rate varied by location. While the VRAP provides real-time data, the VPS has greater versatility. This flexibility and improved performance of the VPS suggest that we will see a greater number of published studies using this system over the coming years.