Single Difference Code-Based Technique for Direct Position Estimation

Global Navigation Satellite System (GNSS) has been widely used in navigation and positioning applications, where precise position and time referencing estimations are required. Conventional GNSS positioning methods require a two-step (2SP) process, where intermediate measurements such as Doppler shift and time delay of received signals are computed and then used to solve for the receiver’s position. Alternatively, to acquire superior levels of sensitivity and operation under challenging environments, Direct Position Estimation (DPE) was proposed to estimate the position directly from the received signal without intermediate variables. However, the positioning resilience of DPE method is still under the influence of common error and bias terms, like the satellite clock bias, ionospheric error and tropospheric error. In conventional 2SP method, Differential Global navigation satellite system (DGNSS) technique is commonly used to improve GNSS positioning accuracy, among which the Single Difference (SD) between two receivers can help remove satellite clock bias, ionospheric and troposphere errors. With current DPE research focusing on a single receiver, this paper introduces SD approach to the DPE scheme, using SD code observations to reduce influence from satellite clock bias, ionospheric error and tropospheric error. Simulations and experiment have been run to demonstrate and validate the efficiency of the proposed method comparing with the standard DPE approach, in terms of a smaller RMSE of positioning solutions.