Исследование свойств систем раздельной и совместной фазовой синхронизации и оценки позиции и скорости движения приемников ГНСС
A subject of the study are systems of synchronization and motion parameters estimation for global positioning satellite systems (GLONASS, GPS, Galileo and others) receivers. Two synchronization systems are considered in the paper: a traditionally used system with separate synchronization in each navigation channel and an alternative one – with joint synchronization of all the signals. The latter system is called CQLL (coordinate-quartz locked loop). There are four common loops in the CQLL (three coordinate loops and one quartz loop) and N individual loops in accordance with the number of synchronized satellite signals. The common loops are designed for tracking general highly dynamic impacts (such as receiver motion and quartz fluctuation, especially due to shaking), while individual loops – for synchronizing less intensive individual effects (ionosphere, troposphere and some other effects). The aim of this study is to develop recommendations on selecting one of the systems and system parameters depending on environment conditions. A modification of the existing joint synchronization system has been proposed in the paper which leads to full unloading of individual loops from the general effects enabling bandwidths of the individual loops to be very narrow (units of Hz). Experiments based on simulation modeling have been performed, which demonstrated the benefit of the proposed modified system (CQLL system with full unloading of individual loops). It has been shown that within pre-threshold regions both separate and modified joint synchronization systems provide the same dynamic and fluctuation errors for position and velocity estimates if the bandwidth of common loops matches that of the separate synchronization system. However, the joint synchronization system typically has smaller fluctuation errors for tracking phases of each navigation signals which eventually should improve threshold properties of such systems (when narrow bandwidths of individual loops are employed).