There is an international standard regarding survey datums, cave length, cave depth, and pit depth, which this talk will describe.
The DistoX2 survey instrument has been key to accurate and efficient cave surveys. It was discontinued at the end of 2019; an electronics project was started to design a replacement. This ongoing project has investigated 19 digital compass MEMS sensors (Micro-Electro Mechanical System) and selected three devices to compare against the sensor used in the DistoX2. A turntable was designed to look into any non-linear behavior. This led to selecting a sensor for future development.