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Galileo Performances

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GALILEOGALILEO
Title Galileo Performances
Edited by GMV
Level Basic
Year of Publication 2011

Galileo system is a space-based global navigation satellite system (GNSS) that provides reliable positioning, navigation, and timing services to users on a continuous worldwide basis freely available to all.

The Galileo performances are different for each service. For the Galileo Open Service (OS) no specific requirements of integrity are applicable. The performances for horizontal positioning accuracy at 95% for a dual-frequency receiver are 4 m (8 m for vertical accuracy), with an availability of the service of 99%.

In the case of the Galileo Public Regulated Service (PRS), the availability of the service should be 99.5%.

Contents

Galileo Service Level Perfomances

From Galileo Mission High Level Definition, the performances requirements for each service are the following:[1]

Galileo Open Service Performances

Service Performances for Galileo Open Service
Galileo Open Service (positioning & timing)
Single Frequency (SF) Dual Frequency (DF)
Coverage Global
Accuracy (95%) Horizontal: 15 m Horizontal: 4m
Vertical: 35 m Vertical: 8m
Availability 99.8 %
Timing Accuracy wrt UTC/TAI N/A 30 ns
Ionospheric Correction Based on SF Model Based on DF Measurements
Integrity No


In the scope of the IOV tests campaign, early promising performance figures were collected; these figures will further improve as more satellites are launched and more ground stations come on line[2].

Galileo
IOV Galileo positioning performance

Galileo Public Regulated Service Performances

Service Performances for Galileo PRS
Galileo Public Regulated Service (PRS)
Dual Frequency (DF)
Coverage Global
Accuracy (95%) Horizontal: 6.5 m
Vertical: 12 m
Availability 99.5 %
Timing Accuracy wrt UTC/TAI 100 ns
Ionospheric Correction Based on DF Measurements
Integrity Computes Yes
Alarm Limit H:20 m -V:35 m
Time-To-Alarm 10 s
Integrity Risk 3.5x10e-7/150 s
Continuity Risk 10e-5/15 s

Galileo Commercial Service

The Galileo Commercial Service will be a controlled access service operated by Commercial Service Providers, who will make decisions on the offered services: e.g. integrity data, differential corrections for local areas, etc., which will depend on the final characteristics of the other services offered by Galileo.

Segment Performance Drivers

To fulfil the Galileo Services requirements, especially with respect to integrity and continuity, key performance drivers have been defined and flown down to Segment level, i.e. Space Segment (SSEG), Ground Mission Segment (GMS), Test User Segment (TUS), and Ground Control Segment (GCS).

The Orbit Determination & Time Synchronisation (ODTS) performance is also driving the signal performance quality indicator, SISA, which needs to be ensured in all available GMS states. Such ensuring of signal quality directly drives Galileo's integrity services. Furthermore the ground monitoring performance indicator, SISMA, is required for the integrity services, and two GMS states exist that are defined via the related SISMA upper bound performance. The final SSEG and GMS key performance requirements are summarized below and are driving OS as well as SOL service performance. The nominal state is if all Galileo Sensor Stations (GSS) and 27 Signal in Space (SIS) from the operational satellites are available.[3]

Segment Performances for Galileo
Nominal Degraded Service
ODTS /Ranging Accuracy (1 sigma) 65 cm OS
GMS Availability of Navigation 99.95 % OS
SISA 85 cm SoL
SISMA 70 cm 130 cm SoL
GMS Availability of Integrity 94.73 % 5.23 % SoL
SSEG State Probability 94.09 % 5.66 % OS,SoL

Such segment key performances drivers have been independently consolidated through the early GIOVE experimentation activities, which show great consistency with the "designed" performance status.

Combined services performances

Galileo is being designed to be interoperable with other systems and, therefore, it will, in a great many instances, be used as part of a combined service. The identification of combined services is necessary to:[1]

The most obvious systems to be combined with Galileo are the other existing GNSS systems, GPS,GLONASS, SBAS and GBAS as they share with Galileo many characteristics that facilitate a combination at user level. By combining Galileo with other GNSS systems, improved performance in the following domains can be expected:

References

  1. ^ a b Galileo Mission High Level Definition, v3, September 2002.
  2. ^ Galileo Works, And Works Well, ESA, February 2014
  3. ^ Veit Oehler, Jan M. Krueger, Tanja Beck, Michael Kirchner, Hans L. Trautenberg, Jörg Hahn, Daniel Blonski, “Galileo System Performance Status Report,” Proceedings of the ION GNSS 2009, Savannah, GA, USA, Sept. 22-25, 2009.
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