GPS simulators are able to test the integration of a GPS/GNSS receiver into a nav system by generating signals corresponding to virtually any condition including vehicle dynamics. They can also generate signals for other sensors for a comprehensive system test. As the simulator generates satellite data for a given trajectory, it simultaneously calculates position and attitude data in six degrees of freedom in real-time; forward/backward, left/right and up/down as well as the rotations about three perpendicular axes, pitch, yaw, and roll; which can be queried and used in integrated test systems.