Indoor Precise Position System

The present invention relates to an indoor Precise Position System comprising a cell-based structure which cell-based structure provides a wide modular scalability and a subscription principle for high number of moving units. A positioning system according to the invention comprises: - a plurality of systemtransmitters where each systemtransmitter has a unique identification code and comprises a receiver configured to constantly listening to a radio signal and a transmitter configured to transmitting an ultrasound signal, all systemtransmitters are fixed units, i.e. they are stationary; - one or more radiomasters where each radiomaster comprises a radio receiver configured to receive registered information from at least one server and a radio receiver configured to receive a clock signal, also each radiomaster comprises a radio transmitter configured to transmit a radio signal to a group of systemtransmitters related to the radiomaster; - the at least one server comprising -- a register of all systemtransmitters of the system including a 3D position of each systemtransmitter recorded in a fixed geometry system file, -- a register of which radiomaster controls which systemtransmitters, -- a transmission schedule defining a time period or loop for each radiomaster during which time period or loop a sequence of signals are send from a radiomaster to all its related systemtransmitters, and -- comprising a server transmitter configured to transmit registered information and a server transmitter configured to transmit a clock signal; - a plurality of moving units, each moving unit comprising a receiver module configured to constantly listening to radio signals from the one or more radiomasters belonging to the system and configured to receive ultrasound signals from one or more systemtransmitters; and - each moving unit comprises or has access to storage means configured to store data of the fixed geometry system and comprises or has access to a controller or processor configured to calculate the flight time for the ultrasound signals and further comprises or has access to a controller or processor configured to calculate a real-time position based on this information.