1,720,973 research outputs found
European Augmentation Service - a GNSS Monitoring in South Europe Region
No full textSince 1993, the civil aviation community through RTCA (Radio Technical Commission for Aeronautics) and the ICAO (International Civil Air Navigation Organization) have been working on the definition of GNSS augmentation systems that will provide improved levels of accuracy and integrity. These augmentation systems have been classified into three distinct groups: Aircraft Based Augmentation Systems (ABAS), Space Based Augmentation Systems (SBAS) and Ground Based Augmentation Systems (GBAS). The last one is an implemented system to support Air Navigation in CAT-I approaching operation. It consists of three primary subsystems: the GNSS Satellite subsystem that produces the ranging signals and navigation messages; the GBAS ground subsystem, which uses two or more GNSS receivers. It collects pseudo ranges for all GNSS satellites in view and computes and broadcasts differential corrections and integrity-related information; the Aircraft subsystem. Within the area of coverage of the ground station, aircraft subsystems may use the broadcast corrections to compute their own measurements in line with the differential principle. After selection of the desired FAS for the landing runway, the differentially corrected position is used to generate navigation guidance signals. Those are lateral and vertical deviations as well as distance to the threshold crossing point of the selected FAS and integrity flags. The Department of Applied Science in Naples has create for its study a virtual GBAS Ground station. Starting from three GPS double frequency receivers, we collect data of 24h measures session and in post processing we generate the GC (GBAS Correction). For this goal we use the software Pegasus V4.1 developed from EUROCONTROL. Generating the GC we have the possibility to study and monitor GBAS performance and integrity starting from a virtual functional architecture. The latter allows us to collect data without the necessity to found us authorization for the access to restricted area in airport where there is one GBAS installation
Primi risultati del sistema sperimentale GBAS
No full textThe GNSS (Global Navigation Satellite Systems-GPS+GLONASS) are not sufficient to
support Air and Maritime Navigation in specific applications; so it is necessary to introduce Augmentation
Systems. In last years the European Scientific Community are focusing its attention on
Augumentation Systems based on Satellite infrastructure (SBAS - Satellite Based Augmentation
System) and on Ground based one (GBAS - Ground Based Augmentation System).
This one is a implemented system to support Air Navigation in CAT-I approaching operation.
The purpose of this work is to verify GBAS performance. So we started from a data set of measures
collected at the GBAS installation of Milano Linate and we process this with the software
PEGASUS v 4.0.Some results on availability, integrity and accuracy are reported and discussed
GBAS - Ground Based Augmentation System, an Italian Experience
No full textThe GNSS (Global Navigation Satellite Systems) are not sufficient to support Air Navigation
in specific applications; so it is necessary to introduce Augmentation Systems. In the last years
the European Scientific Community are focusing on Augmentation Systems based on Satellite
infrastructure (SBAS - Satellite Based Augmentation System) and on Ground based ones
(GBAS - Ground Based Augmentation System).
The purpose of this work is to verify GBAS performance. We started from a data set of measurements
carried out at the GBAS of Milan-Linate where we work on a ground installation
(GMS – Ground Monitoring Station) that supervise the GBAS signal and that represent, for
our purposes, the Aircraft subsystem. So the set of data collected is to be considered in RTK
mode and after the measures session we processed them with the software PEGASUS v 4.0.
Some results on availability, integrity and accuracy are reported and discussed
A New Integrated Methodology in Course Keeping and Manoeuvring Sea-Trails of High Speed Craft
No full textPositioning, Course Keeping And The Measurement Of Motion Of High Speed Craft By Means Of New Navigational Methodologies During Manoeuvring Sea Trials
No full textVirtual Ground Based Augmentation System
No full textSince 1993, the civil aviation community through RTCA (Radio Technical Commission for Aeronautics)
and the ICAO (International Civil Air Navigation Organization) have been working on the definition of GNSS
augmentation systems that will provide improved levels of accuracy and integrity. These augmentation systems have
been classified into three distinct groups: Aircraft Based Augmentation Systems (ABAS), Space Based Augmentation
Systems (SBAS) and Ground Based Augmentation Systems (GBAS).
The last one is an implemented system to support Air Navigation in CAT-I approaching operation. It
consists of three primary subsystems: the GNSS Satellite subsystem that produces the ranging signals and navigation
messages; the GBAS ground subsystem, which uses two or more GNSS receivers. It collects pseudo ranges for all
GNSS satellites in view and computes and broadcasts differential corrections and integrity-related information; the
Aircraft subsystem. Within the area of coverage of the ground station, aircraft subsystems may use the broadcast
corrections to compute their own measurements in line with the differential principle. After selection of the desired
FAS for the landing runway, the differentially corrected position is used to generate navigation guidance signals.
Those are lateral and vertical deviations as well as distance to the threshold crossing point of the selected FAS and
integrity flags.
The Department of Applied Science in Naples has create for its study a virtual GBAS Ground station.
Starting from three GPS double frequency receivers, we collect data of 24h measures session and in post processing
we generate the GC (GBAS Correction). For this goal we use the software Pegasus V4.1 developed from
EUROCONTROL. Generating the GC we have the possibility to study and monitor GBAS performance and integrity
starting from a virtual functional architecture. The latter allows us to collect data without the necessity to found us
authorization for the access to restricted area in airport where there is one GBAS installation
Galileo Signal Design: State of Art
No full textThe Global Positioning System (G.P.S.) has been a revolutionary system that opened new opportunities and enabled innovative services for both governmental and civilian applications. Rapidly, an efficient and reliable positioning system has become mandatory for public protection and security applications. As consequence Europe has realized the need to develop an independent positioning system (Galileo) with enhanced capabilities, performance and an unconditioned reliability. Galileo has pursued from the very first moment the goal of having wide band signals in all its assigned frequency bands but it was a particularly difficult task because the band E1 and L1 had already congested. It will be at the same time compatible and inter operable with American G.P.S. Compatibility refers to the ability of space based positioning, navigation and timing (P.N.T.) services to be used separately or together without interfering with each individual service or signal, and without adversely affecting navigation warfare. Interoperability refers to the ability of civil space base P.N.T. services to be used together to provide better capabilities at the user level than would be achieved by relying solely on one service or signal. To achieve this it was necessary planning special signal with particular waveform. An important aspect in designing the modulation scheme is obtain good spectral properties and suitable spectral shaping, low interference with existing G.P.S. signals, good root mean square (R.M.S.) bandwidth, good time resolution (in order to allow the separation between channel paths and to decrease the synchronization errors). The family of modulations that allowed this was the B.O.C. (Binary Offset Carrier). This paper is concerned with this modulation: it will be described their performance both the transmitter that the receiver point of view. Moreover after a brief description of Galileo signal in which will highlight the differences between the various services to be provided by Galileo itself, will be introduced the AltBOC modulation used on E5. Attention will focused on the signal processing techniques required to process the AltBOC modulation because they are much more challenging than those for traditional BPSK or even for the usual B.O.C. modulation. This stems from the extremely large bandwidth and from the complex interaction of 4 components of spreading code
Aided GPS/GLONASS navigation in urban environment
No full textIn signal-degraded environments such as urban canyons or mountainous areas many GPS signals are blocked by natural or artificial obstacles or severely degraded; hence GPS-only cannot guarantee an accurate and continuous positioning. The multi constellation approach, integrating different GNSS systems, is a possible way to fill this gap. GLONASS, the Russian navigation satellite system, is currently the main candidate as element of a multi constellation; it is nearly fully operational and its inclusion guarantees an improvement of the satellite availability. Another possible future component of integrated GNSS system is the European Galileo currently in a validation phase with only 4 satellites in orbit GIOVE A/B experimental satellites and 2 Galileo for the IOV phase.
In this work GPS/GLONASS systems are combined and relative single point algorithm performance is assessed for different configurations in signal-degraded scenario such as urban canyon. GPS/GLONASS multi-constellation use involves the addition of a further unknown to estimate, i.e. the intersystem time scale offset, which requires the “sacrifice” of one measurement.
The intersystem offset is observed to be quasi-constant, so an aiding can be introduced to account for its behavior. A similar approach can be adopted for altitude considering its typical variations in urban scenario.
The considered estimation techniques are least squares and Kalman filter, commonly adopted to calculate the navigation unknowns from pseudorange measurements. The least squares method uses a model relating measurements and state with the drawback of solution unavailability during GNSS outages (very frequent in urban areas); to improve the continuity constrained least squares adjustments are considered. Kalman filter uses, in addition to a measurement model, a process model expressing the unknown dynamics and allowing the state estimation in case of GNSS outage.
The main purpose of this work is the performance assessment of a multi-constellation system relative to GPS-only adopting least squares or Kalman filter estimators
Multi-Constellation System as Augmentation to GPS Performance in Difficult Environment or Critical Applications
No full textThe GPS Standard Positioning Service (SPS) does not provide suitable performance in all environment conditions or in every possible applications. In severely signal degraded environments, e.g. mountainous or urban areas, where a lot of GPS signals are blocked by buildings or natural obstacles, the positioning is inaccurate because of bad satellite configuration or impossible owing to lack of minimum number of visible satellites. Otherwise GPS SPS is inadequate for critical safety applications like aircraft take-off or landing, because does not satisfy the Required Navigation Parameters (RNP) relative to these flight phases.
To solve the GPS gap on regional scale, space-based augmentations could be employed. In this study a simulation is carried out, considering GLONASS and EGNOS GEO constellations and a set of 3 geosynchronous satellites (similar to QZSS space segment). A software for constellation analysis is developed in MATLAB® environment to evaluate the considered augmentations performances in critical conditions (urban canyon or critical phase of flight). The used indicators to evaluate coverage performance are the VSN (Visible Satellites Number), DOP (Dilution of Precision) and the probability that integrity is available to be computed in autonomous
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