RTK navigation technology allows the robotic mowers to move around the garden with high precision without the need for perimeter wire. The acronym RTK stands for "Real-Time Kinematic", which translates to real-time position correction. The system works on the principle of two satellite signal receivers. One is placed on a fixed reference station, which is usually installed on a house or other location with a good view of the sky. The second receiver is located directly in the mower. Conventional GPS navigation has a deviation of a few metres. The reference station, however, knows its exact and unchanging position and so can calculate the actual error in the satellite signal. It sends this correction information in real time to the mower, which is then able to refine its own position with a deviation of only a few centimetres. This accuracy allows the mower to move in perfectly straight and systematic strips. The user can easily create virtual property boundaries and so-called "no-go zones" such as flower beds or playgrounds in the mobile app without having to physically install anything in the ground.