In this paper, we present the design and implementation of a high precision Indoor Positioning System (IPS), with average accuracy within 0.5 meter and 90% of positioning errors smaller than 0.9m in three trial environments. The transmitter continuously transmitted periodic PN code and the multiple receivers at fixed locations performed signal acquisition, tracking, and position calculation. Several techniques were also integrated to combat the severe multipath effect. Finally, a Software Defined Radio (SDR) platform with baseband processing implemented in FPGA was constructed for real-time demonstration and validation of the effectiveness of this proposed IPS solution.