LOSNUS: Ultrasonic indoor locating for numerous static and mobile devices

In the past years a lot of research has been conducted in the field of ultrasonic location systems. Usually systems use time of flight measurement of the ultrasonic signal to determine the distance between transmitters and receivers. Mostly indoor location systems are used for tracking of mobile units. However, device location is getting growing importance in integration of numerous static sensor/actuator devices in WSN and in the evaluation of sensor array data. The high accuracy (≤10 mm) and a locating rate up to about 10 cycles/s of the ultrasonic indoor location system LOSNUS presented in this paper supports both locating of static devices and tracking of mobile devices. The principle of operation and the design of the transmitting system, realization elements of receiver nodes, and a location server calculating node locations by TDoA algorithms are presented in this paper. Clock error, quantization noise, and the influence of transmitter delay on echo suppression are crucial points discussed in detail.