Synthesis of one-stage signal processing algorithm for space radio navigation receiver

Abstract

High requirements are imposed on modern user navigation apparatuses (UNA) of global navigation satellite systems (GNSS) in terms of the navigation support accuracy. As a rule, the UNA is built according to the scheme with two-stage signal processing. At the first stage, navigation signals are received and transferred to the intermediate frequency, signals are searched for and tracking of signal parameters (delay, phase, Doppler frequency shift) is performed. At the second stage, pseudo-ranges, pseudo-phases and pseudo-Doppler frequencies are measured, digital information is selected from the received radio signals and the navigation problem is solved, i.e. the coordinates and components of the user’s velocity vector are determined. The use of one-stage processing of navigation signals is one of the promising areas for further improving the navigational sighting accuracy in a UNA. In this case, all signals are processed in a single integrated filter with simultaneous solution of the navigation task. The article considers the synthesis of an optimal one-stage algorithm for processing GNSS signals using the theory of optimal filtering. This synthesis is aimed at providing the best accuracy in estimating the coordinates and components of the user’s velocity vector. The final algorithm implements vector tracking for the delays in received signals and their phases. Vector tracking loop includes a standard set of correlators, delay and phase discriminators and an integrated filter of the augmented state vector.