Position estimation using hyperbolic model for time difference of flight of ultrasonic

Three ultrasonic transmitters are in line at one side and transmit ultrasonic signals that contain different 9bit pseudo-random codes at the same time. The receiver measures time difference of flights (TDOFs) of transmitted signals by optimum correlation detection. According to TDOF, the possible position of the receiver is represented by hyperbolic curves. An intersection of the hyperbolic curves is the position of the receiver. The intersection is calculated by bisection method. The proposed system can be installed easily and the cost of installation is low. In the experimental results, the position errors become large when the receiver is at the position far from central transmitter and are correlated about (u, v) position.