Comparison and Evaluation of Clock-aided and Classical Multi-GNSS Flight Navigation

Maintaining the navigation performance with respect to a certain standard is of prime importance in civil aviation operations. In global navigation satellite system (GNSS) based position estimates, the height component is less accurate specifically due to the receiver clock bias. Further, the height component is of high relevance in all phases of flight navigation. With the concept of receiver clock modeling (RCM), sometimes called as clock coasting, the accuracy of the height component could be improved by a large extent. In this paper, we present experimental results of code-based flight navigation computed using two different methods. GNSS observations are recorded on an aerial flight for about three hours with multiple GNSS receivers and an inertial measurement unit (IMU), some of these receivers are connected with external atomic clocks. Data captured is processed post-flight; position and clock bias are estimated at first using multi-GNSS code observations with a Linearized Kalman filter (LKF) without applying the concept of RCM; later using LKF approach and applying the concept of RCM. Finally, the estimated positions are compared with the reference trajectory and the topocentric coordinate differences are evaluated using both methods. Experimental results demonstrate that the precision in the height component is improved by about 80% using GPS and GLONASS observations with RCM applied compared to a positioning solution without applying RCM. There is no significant difference in the horizontal coordinates for the navigation solutions computed using the two different methods.