1,720,997 research outputs found
Performance Analysis of MBOC, Alt BOC and BOC Modulation in Terms of Multipath Effects on the Carrier Tracking Loop within GNSS Receivers
No full textPhase lock loop false lock avoidance in presence of global navigation satellite system signal
No full textIn 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
Signal Quality Monitoring: Correlation mask based on Ratio Test metrics for multipath detection
No full textIn 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 following ratios: Ratio Test, Delta Test and Lambda Test. Once the test metrics built, their values are compared to predetermined thresholds during the Signal Quality Monitoring (SQM) activity.
Although a huge amount of work on those metrics is present in literature, this paper will present a new way of operation for the threshold settings. A threshold mask is built around the shape of the correlation function in order to detect in real time the presence or absence of a distortion guaranteeing a desired confidence level.
The reliability of this design criterion will be proved in the paper. A simulations campaign is performed to determine and analyse the SQM techniques and their optimum parameters in order to obtain the so–called Receiver Operative Characteristic (ROC)
A software receiver phase lock loop analysis and design to implement adaptive phase tracking using a finite impulse response loop filter
No full textIn 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 simple method to make its bandwidth adaptive with respect to the noise that affects the signal
REFLECTED GNSS SIGNALS RECEIVED ON UNMANNED AERIAL VEHICLE PLATFORM: A FEASIBILITY STUDY
No full textFor remote sensing purposes, the Earth’s surface can be
characterized analysing the reflection of a signal generated
from a dedicated sensor which, in turn, must receive the
scattered waves. Among the possible choices, GNSS (Global
Navigation Satellite System) signals represent an innovative
active source for the Earth remote sensing in L band. In this
framework, we started the design of a GNSS-R (GNSSReflectometry)
receiving system based on the N-Gene
Navigation SW receiver, developed by the NavSas group of
ISMB. Experimental characterization activities will be
performed both on ground and on-board a small U.A.V
(Unmanned Aerial Vehicle) platform.
Together with the system design, a feasibility study
based on simulations was carried out to get ready the
acquisition and processing stages for the future experimental
campaign. Simulation results related to the retrieval of the
geometrical delay and Doppler shifts expected on the
reflected signal (under the hypothesis of specular scattering)
are presented
- …
