When satellites are not visible, an LPS (Local Position System) is the right choice. Inside tunnels, in densely built-up areas or forests, satellites are not always reachable.
Total station with Topcon PowerTrac
Standard robotic total station, also usable for surveying
Total station accuracy
100% slope control sensor
Simple, fact conversion between GNSS and LPS
Re-acquire prism lock directly from control box screen
