EGNOS Performances

EGNOS
Title	EGNOS Performances
Author(s)	GMV.
Level	Basic
Year of Publication	2011

EGNOS perfformances are issually described in terms of accuracy, integrity, availability and continuity.

EGNOS Performances Requirements

The performances required to EGNOS as per the EGNOS Mission Requirement Document are presented in the following table.

Service	Service Coverage	Accuracy (95%)		Integrity				Continuity	Availability
		Lateral	Vertical	HAL	VAL	TTA	Integrity Risk
Open Service	EU25 States (plus Norway and Switzerland) land masses	3m	4m	-	-	-	-	-	99%
SoL En-route and NPA	FIRs of ECAC 96	220m	-	556m	-	10s	1e-7/hour	1e-5/hour	99.9%
SoL APV-I	Land Masses of ECAC 96	16m	20m	40m	50m	6s	2e-7/150s	8e-6/15s	99%

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Monitoring of EGNOS Performances

EGNOS performances are being monitored continuously by several entities, such as ESSP and ESA.

Typical Performances

Early 2011, the performances provided by EGNOS are presented in next figures – for day 7th Feb. 2011, considered to be a representative day. The actual EGNOS messages have been taken from the EGNOS Message Server. Plots are provided by the eclayr tool.

Availability

EGNOS typical availability

EGNOS availability map is provided in next figure together with the iso-lines of availability compliance to APV-I service level availability requirements (i.e., HPL < 40 m and VPL < 50 m). The period of analysis corresponds to one day with the inner iso-line delimiting the user locations where a service level over 99% availability is achieved.

Continuity

EGNOS typical continuity

EGNOS continuity map is provided in next figure together with the iso-lines of continuity risk compliance to APV-I service level. The continuity risk is computed as the probability of having a continuity event (Protection Levels > Alarm Limits) during the period [T0, T0 + 15 sec] provided that the service was available at T0 (Protection Levels < Alarm Limits). The inner iso-line – 1e-4 - delimits the user locations which did not have a single continuity event during the analyzed day.

Accuracy

EGNOS typical accuracy

EGNOS vertical accuracy map is provided in next figure together with the iso-lines of 95% Vertical Position Error – meters -. Users inside the inner iso-line had a vertical accuracy below 2 m (95%) for the analyzed day.

Integrity

EGNOS typical integrity

EGNOS vertical integrity margins are provided in next figure as maximum Vertical Safety index map (maximum ratio between the vertical user error and the vertical user protection level). All values are under one meaning that no integrity failures at user level were been observed.