Iterative altitude-aiding algorithm for improved GNSS positioning

The system proposed in this study relies on a WAVE P2P network, which is a proper standard to fit the vehicular environment wireless communications requests. Starting from the chance to exchange information given by this infrastructure, the possibility to improve the performance of a global navigation satellite system (GNSS) receiver based on a Kalman filter is considered. This improvement is obtained exploiting the external altitude measurements provided by other peers in the network, equipped with GNSS receivers. The topic of an altitude-aided system has been described in a previous work, that highlighted the need for a parameter that points out the effectiveness and the consistency of th…

The Kalman Filter and Its Applications in GNSS and INS

This chapter contains sections titled: Introduction Review of Kalman Filtering and Extended Kalman Filtering for Navigation EKF-Based PVT Computation in a Stand-Alone GNSS Receiver Inertial Navigation Fundamentals IMU Alignment General Architecture for the Loose Integration General Architecture for the Tight Integration General Architecture for the Ultra-Tight Integration Conclusions References Appendix A

A software receiver phase lock loop analysis and design to implement adaptive phase tracking using a finite impulse response loop filter

In this paper we analyze the design of a digital Phase Lock Loop (PLL) for a Global Navigation Satellite System (GNSS) software receiver. Even if the topic of phase tracking has been widely studied, we found it useful to provide a short walkthrough for the design of a PLL in a real software receiver, avoiding to introduce the common theoretical phase-based model and aiming to the practical implementation of a system that deals with frequencies. Nonetheless, our analysis and design will grow away from the canonical approach, in the way that we will not resort to analog filter theory. The result is a PLL which is more reactive than the ones usually found in literature and that implements a si…

KALMAN FILTERS FOR GNSS APPLICATIONS

Phase lock loop false lock avoidance in presence of global navigation satellite system signal

In this paper we analyse the operation of a fully digital Phase Lock Loop (PLL) in a false lock regime, using real data. The issue has been noticed while we were testing performance of our software receiver in a moving user scenario. While the phenomenon of false lock has been described in other papers about PLLs, our intent is to describe a practical, and in our opinion interesting, issue we encountered and how we got over it.

Sistema di posizionamento geo-spaziale cooperativo operante con sistemi di navigazione globale satellitare e reti di telecomunicazione wireless, relativo procedimento e apparato di posizionamento geo-spaziale

Is it possible to define a fully digital state model for Kalman filtering?

A software receiver adaptive phase lock loop method

The aim of this paper is to introduce a new and relatively simple algorithm which is capable to tune the parameters of the loop filter in a phase lock loop, like the one that can be found in a global navigation satellite system receiver. The parameters are chosen while the system is running, in order to make the bandwidth of the filter adaptive with respect to the signal dynamic and strength. A wider bandwidth is obtained to make the filter more reactive when searching the carrier, while the bandwidth gets narrower when the system is in the tracking state, in order to cut off as much noise as possible. The algorithm is based on the observation of the estimated variance of the phase lock loo…

Improved GNSS positioning exploiting a vehicular P2P infrastructure

This paper considers the possibility to exploit external altitude measurements to improve the performance of a Kalman based GNSS receiver. The altitude measurements are provided by means of a peer to peer network, that is supposed to be based on the evolution of the 802.11 standard for the vehicular environment, namely the WAVE (802.11p). The performance of such a system are investigated for different characteristics of the aiding measurement and for a different number and disposals of the aiding peers. The aiding measurement is obtained starting from the altitude measurements that the other peers in the network send to the aided user. The experiments highlight the need for a parameter that…

Peer to Peer Equation Augmentation for an Altitude Aided GNSS Receiver

This paper considers the possibility to integrate external altitude measurements with a Kalman based Global Navigation Satellite System (GNSS) receiver in a peer to peer scenario. The performance of such a system is investigated for different characteristics of the aiding measurement and for different degree of trust of the receiver upon the aiding measurement. The aiding measurement is obtained starting from the altitude measurements that the other peers in the network send to the aided user. The experiments highlight the need for a parameter that points out the effectiveness and the consistency of the computed aiding measurement. To this purpose, a reliability index is proposed, on the ba…

Signal Quality Monitoring: Correlation mask based on Ratio Test metrics for multipath detection

In any measurement process, the observation is error affected: calibration and careful measuring procedures can reduce the error components but are unable to completely eliminate them. The capability to monitor and to detect any disturbances on the spreading sequences transmitted by the satellites is then of primary importance. Quality Control techniques based on a modified tracking architecture, which provides a certain number of correlator outputs, are analysed in this paper. Such outputs are used to build a metric used to monitor in real-time the reliability of the signal being tracked. In literature, several definitions of metrics can be found. The mainly used metrics are based on the f…