Abstract: A helmet-mounted tracker and boresighting system incorporated paired receivers on opposing sides of the helmet worn by the user (e.g., left/right, top/bottom) that receive a directional signal from directional transmitters placed at fixed locations throughout the target environment (e.g., a mobile platform, multilevel structure, or simulated environment). Each paired antenna generates an RF signal based on the received directional signal; the paired RF signals are summed to determine the current alignment of the helmet (and head) to the directional transmitter. Alignment information may be used to calibrate or correct inherent drift of the inertial measurement unit (IMU) of the helmet-mounted head tracker.