Estimation of the GPS to Galileo time offset and its validation on a mass market receiver

Gioia, Ciro; Fortuny-Guasch, J.; Pisoni, Fabio

doi:10.1109/navitec.2014.7045145

Cited by 10 publications

(11 citation statements)

References 9 publications

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“…GPS and Galileo adopt different time scales, hence when GPS and Galileo observables are used together, the clock inter-system bias has to be added in the navigation solution [ 7 ]. Thus,

assumes the following form:

where

are the receiver coordinate differences, expressed in the WGS84 frame.…”

Section: Multi-constellation Solutionmentioning

confidence: 99%

“…Moreover, a composite design matrix is used for the GPS/Galileo case. In this case, the presence of an inter-system bias is accounted for [ 7 ].…”

Section: Integrity Algorithmmentioning

confidence: 99%

“…Among the proposed solutions, the multi-constellation approach, i.e. , the joint use of measurements provided by several GNSSs, has the potential to enable GNSS usage in environments where navigation using a single GNSS is usually precluded [ 3 , 4 , 5 , 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

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Galileo: The Added Value for Integrity in Harsh Environments

Borio

Gioia

2016

Sensors

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A global navigation satellite system (GNSS)-based navigation is a challenging task in a signal-degraded environments where GNSS signals are distorted by multipath and attenuated by fading effects: the navigation solution may be inaccurate or unavailable. A possible approach to improve accuracy and availability is the joint use of measurements from different GNSSs and quality check algorithms; this approach is investigated here using live GPS and Galileo signals. A modified receiver autonomous integrity monitoring (RAIM) algorithm, including geometry and separability checks, is proposed to detect and exclude erroneous measurements: the multi-constellation approach provides redundant measurements, and RAIM exploits them to exclude distorted observations. The synergy between combined GPS/Galileo navigation and RAIM is analyzed using live data; the performance is compared to the accuracy and availability of a GPS-only solution. The tests performed demonstrate that the methods developed are effective techniques for GNSS-based navigation in signal-degraded environments. The joint use of the multi-constellation approach and of modified RAIM algorithms improves the performance of the navigation system in terms of both accuracy and availability.

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“…GPS and Galileo adopt different time scales, hence when GPS and Galileo observables are used together, the clock inter-system bias has to be added in the navigation solution [ 7 ]. Thus,

assumes the following form:

where

are the receiver coordinate differences, expressed in the WGS84 frame.…”

Section: Multi-constellation Solutionmentioning

confidence: 99%

“…Moreover, a composite design matrix is used for the GPS/Galileo case. In this case, the presence of an inter-system bias is accounted for [ 7 ].…”

Section: Integrity Algorithmmentioning

confidence: 99%

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Galileo: The Added Value for Integrity in Harsh Environments

Borio

Gioia

2016

Sensors

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“…Following the rapid evolution of GNSS systems and receivers, the widespread use of combined multi-GNSS receivers in mass-market applications is expected. Gioia et al (2014) demonstrated the benefits of the Galileo plus GPS solution with respect to the GPS-only case in terms of accuracy and availability. This multi-constellation approach increases the available measurements, improving the accuracy and continuity of the position-velocity-time (PVT) solution.…”

Section: Introductionmentioning

confidence: 97%

Impact of Galileo-to-GPS-Time-Offset accuracy on multi-GNSS positioning and timing

2021

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The combined use of multi-GNSS systems in positioning, navigation and timing requires taking into account the variable time offset between the individual system times. This offset can be determined at the user level as an additional unknown in the position-velocity-time (PVT) solution when a sufficient number of satellites is visible. However, a known value of the inter-system bias can also be injected in the PVT algorithm. We investigate in which situation determining the Galileo-to-GPS-Time-Offset (GGTO) or fixing this parameter to a known value provides the best PVT solution and quantify the impact of a biased fixed GGTO value on the PVT solutions. Our results indicate that the recommendation on fixing or determining the GGTO, as well as the impact of a biased fixed GGTO value, heavily depends on the receiver noise level. In high visibility conditions, fixing the GGTO provides a similar or better solution than determining the GGTO if the accuracy of the fixed GGTO is better than 2 ns for a high precision receiver and 7 ns for a smartphone. Furthermore, an extreme bias of 20 ns on the fixed GGTO with respect to the true value induces an increase in the position or timing errors lower than 50% for a smartphone, while up to 150% for a high precision receiver. As a consequence, fixing the GGTO should be preferred in mass-market receivers, while determining the GGTO should be preferred in high precision receivers. The study also shows that there is no significant correlation between the superiority of determining or fixing the GGTO and either the dilution of precision or the number of visible satellites.

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“…In fact, in the multi-constellation case, the offset is partially known, hence different strategies can be adopted to accommodate for such offset, while in the considered case the offset among the nodes is totally unknown. In [8][9][10], the authors proposed a comparison between different strategies to account for the inter-system bias; analogously, in this paper, a comparison between the proposed approach and the classical method (that does not compensate for the INB) is provided. The INB is composed of two terms: the difference between the network time scales and a device-dependent component.…”

Section: Introductionmentioning

confidence: 99%

Multi-Network Asynchronous TDOA Algorithm Test in a Simulated Maritime Scenario

Gioia

Sermi

Tarchi

2020

Sensors

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In the last few years, the number of applications relying on position of vessels at sea has grown significantly. Usually, these applications exploit information provided by the Automatic Identification System (AIS). Unfortunately, the cooperative nature of AIS makes it vulnerable to different types of attack. Therefore, especially for critical applications, the veracity of the position information reported in the AIS message needs to be verified. Several techniques can be adopted to this end. This paper presents a mathematical extension of the traditional Time Difference Of Arrival (TDOA) localisation technique allowing merging TDOA measurement from synchronous and non-synchronous receivers. This technique was tested in a simulated scenario, where the position of a moving target was estimated using different configurations of the receivers network. The robustness of the proposed algorithm with respect to the traditional one is demonstrated. The proposed approach, which is derived form satellite applications, is not limited to the AIS signals or to the maritime domain, and it can be adopted to estimate the position of any radiofrequency transmitter, by employing a suitable number of non-synchronous receivers.

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Estimation of the GPS to Galileo time offset and its validation on a mass market receiver

Cited by 10 publications

References 9 publications

Galileo: The Added Value for Integrity in Harsh Environments

Galileo: The Added Value for Integrity in Harsh Environments

Impact of Galileo-to-GPS-Time-Offset accuracy on multi-GNSS positioning and timing

Multi-Network Asynchronous TDOA Algorithm Test in a Simulated Maritime Scenario

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