Abstract: A high performance ultrasonic location system is proposed. Both infrared and radio signals are applied as synchronizing signals，forming a locating structure with separated transmitter and receiver. Pseudo random M sequence is utilized as spread spectrum carrier to form a CDMA-based multi-station mechanism. Wide-angle probes are designed for expanding the detecting area. In addition， a temperature compensation circuit is designed to improve the 　　measurement accuracy. This system can achieve 10 Hz sample rate and centimeter level measurement accuracy，and is verified to be effective for locating moving indoor targets.

Key words: indoor location, ultrasound, CDMA, embedded system