A location determination system (100) utilizes a low accuracy timing infrastructure
(106) to synchronize a personal tracking device (120) having high
accuracy timing location determination devices integrated therein. The PTD (120)
includes a radio frequency (RF) location unit (102) and integrated sensors,
such as altimeter (132), GPS receiver (134) and inertial navigation
unit (IMU) (136). The RF location unit (102) receives a synchronization
command from the low accuracy timing infrastructure (106) and provides timing
data representing range information in response thereto. The range information
is used by the high accuracy timing infrastructure (180) to compute updated
X, Y, Z coordinates of the PTD (120).