Doppler Measurement Accuracy in Standard and High-Sensitivity GNSS Receivers

Abstract

Doppler frequency estimates generated by a GNSS receiver are essential for the evaluation of the user velocity. In this paper, a theoretical framework allowing the evaluation of Doppler measurement accuracy is introduced. The variance of Doppler estimates is related to the Carrier-to-Noise density power ratio (C/N0) and the type of processing adopted by the receiver. Both standard sequential and highsensitivity receivers adopting block processing techniques are considered. A general formula quantifying the Doppler variance is derived and applied to these two receiver architectures. Moreover, the concept of Doppler bandwidth is introduced for quantifying the amount of input noise transferred to the final Doppler estimates. The generality of the theory is validated using live GPS data and a good agreement between theoretical and empirical results is found.