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1 EGNOS L1 MARITIME SERVICE

EGNOS is the satellite-based positioning service over

Europe which provides better accuracy with respect

to GPS standalone position. In addition, EGNOS

provides Integrity, which can be suitable for safety

critical applications in the maritime sector.

The EC (European Commission) and EUSPA

(European Union Agency for the Space Programme)

are working on the future EGNOS L1 Maritime

Service with target service declaration by end of 2023

or beginning of 2024. This service will be defined in a

Service Definition Document and notifications of

predicted EGNOS unavailability will be provided to

mariners through Maritime Safety Information (MSI)

service. At the same time, IEC TC80 (International

Electrotechnical Commission Technical Committee) is

developing a new standard for SBAS L1 receiver

equipment (IEC 61108 7, [1]), which will include the

performance requirements and methods of testing

required for maritime navigation. This standard IEC

61108 7 plans to be published by end of 2023. From

that moment, vessels will start using type-approved

SBAS L1 receivers (compliant with IEC 61108 7) in

order to ensure the required operational performance

for the maritime community.

This article presents the EGNOS (European

Geostationary Navigation Overlay Service)

performance observed along several maritime

campaigns carried out in European waters.

These results in real maritime environment aim at

demonstrating that EGNOS L1 service is suitable to

support navigation in ocean waters, coastal waters

and harbour entrances/approaches according to the

operational requirements defined in the IMO Res.

A.1046 (27) [2]. Thus, this assessment is an evidence of

the benefits of using EGNOS, encouraging maritime

community to equip their vessels with type-approved

SBAS L1 receivers and use EGNOS L1 service once it

is operational.

EGNOS Performance in Several Maritime Campaigns

E. Lacarra

, R. Gonzalez

& M. Lopez-Martinez

EGNOS Satellite Services Provider, Madrid, Spain

European Union Agency for the Space Programme, Prague, Czech Republic

ABSTRACT: This article presents the EGNOS (European Geostationary Navigation Overlay Service)

performance observed along several maritime campaigns carried out in European waters with the objective to

demonstrate the availability of corrections and the suitability of the accuracy to support maritime navigation.

The regions selected correspond to those located in the border area of EGNOS coverage and include the

following campaigns: Norwegian coast in 2018, Southwest of Europe in 2018 & 2019, Finnish coast in 2019,

Baltic Sea in 2021 and Irish coast in 2022.

These results in real maritime environment aim at demonstrating that EGNOS L1 service is suitable to support

maritime navigation in ocean waters, coastal waters and harbour entrances/approaches according to the

operational requirements defined in the IMO Res. A.1046 (27), being beneficial for maritime community.

http://www.transnav.eu

the

International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 17

Number 4

December 2023

DOI: 10.12716/1001.17.04.

856

2 METHOD OF TESTING

Different GNSS campaigns have been carried out

along different European waters, trying to cover the

border areas of EGNOS coverage: Northwest area

within the Norwegian coast and Irish coast, Northeast

within the Baltic Sea and South west within a route

from South of Iberian Peninsula to Canary Ireland.

Different types of receivers were installed on board of

a vessel to output the SBAS corrected position and the

GNSS observation measurements. Additionally, a SIS

L1 recorder was also installed to be able to replay in

the laboratory the recorded GNSS signals and feed

them into different receivers to compute again

different positioning solutions, such as GPS

standalone.

There are different types of receivers in these

GNSS data campaigns: high-end receivers, maritime

receiver and software (SW) receiver.

− High-end receiver: It is able to provide high level

of performance and output a wide variety of GNSS

information useful for post-processing analysis.

High-end receivers are normally used in marine

engineering and surveying operations.

− Maritime receiver: A receiver brand that is

commonly used for maritime navigation.

− SW receiver: This type of receiver is used in the

laboratory to initially test the performance of a

software implementation. The SW receiver was fed

with the GNSS observation measurements

provided by the other receivers installed on board

the vessel in order to compute SBAS or GPS

position in the laboratory.

Once the standard for SBAS L1 receiver equipment

(IEC 61108 7, [1]) is published, vessels will start being

equipped with type-approved SBAS L1 receivers

(compliant with IEC 61108 7) in order to ensure the

required operational performance (i.e. harbour

entrances/approaches). These types of receivers shall

have been developed according to the specification

and shall have passed successfully the required

methods of testing described in that IEC standard.

Considering that the standard will be published by

end of 2023, there were no receivers in line with

potential IEC 61108 7, [1] by the time of the data

campaigns. However, the software receiver used

follows the guidelines developed for SBAS maritime

receivers, implementing the requirements defined as

the baseline for the standard under development.

Details about the methodology of computing can

be found in [3]. Receiver was configured to compute

navigation data and store the associated outputs

every 1 second (1 Hz frequency). Once the vessel had

concluded his route and the equipment was collected,

receiver outputs were analysed to obtain the

following:

− Real position. The real position considered as

reference for the position error estimation was

computed in post-processing using Precise Point

Positioning (PPP) with the GNSS observations data

obtained by a high-end receiver.

− SBAS Navigation solution. The SBAS Navigation

solution using EGNOS was computed by the

receiver and reported in the output files.

− GPS-only solution. GNSS radio frequency L1

signal recorded during the maritime dynamic data

campaign was replayed in the receiver to obtain

GPS standalone solution. GPS-only solution is

compared with SBAS solution to show the

improvements of using SBAS.

Based on this, the following performances were

obtained:

− Accuracy: Horizontal Navigation System Error

(HNSE) or Horizontal Position Error (HPE)

achieved 95% of the time. Horizontal Navigation

System Error is the 2D radial error between the

instantaneous position solution (SBAS or GPS)

with respect to the instantaneous real position

(computed using PPP in post-processing). It is

noted that HNSE / HPE was computed every 1

second.

− Position Availability: Percentage of time that the

receiver is providing the corresponding position

(EGNOS or GPS).

Considering that EGNOS L1 maritime service

plans to support the navigation in ocean/coastal

waters and harbour entrances/approaches according

to the operational requirements defined in the IMO

Res. A.1046 (27) [2], these performances will be

compared with the accuracy requirement of 10 meters.

3 EGNOS SIS AVAILABILITY

EGNOS Signal in Space was 100% during all the

maritime campaigns, which meets the 99.8% EGNOS

signal in space availability requirement of IMO Res.

A.1046 (27) [2]. The fact that EGNOS system has two

operational geostationary satellites ensured that at

least one satellite was transmitting EGNOS

corrections during the whole time. As an example,

from January 2017 to January 2023, EGNOS SIS

availability was 100%. Figure 1 shows the EGNOS SIS

availability over the last 6 months, and the SIS

availability per SBAS satellite (PRN136 and PRN 123

are the EGNOS GEO satellites in operation since

March 2020).

Figure 1. EGNOS SIS availability trending (last 6 months)

4 MARITIME CAMPAIGNS

4.1 Norwegian coast in 2018

In order to assess the EGNOS performance at user

level in the maritime domain at high latitudes in

857

Europe, a data campaign was carried out along the

Norwegian Coast. In the northbound, the vessel

departed from Trondheim to Kirkenes. The

southbound was from Kirkenes to Bergen.

Figure 2. Vessel trajectory through Norwegian Coast

The Horizontal Navigation System Error (HNSE)

histogram was computed for the EGNOS High-end

receiver (coral), the EGNOS software receiver (blue)

and the GPS standalone receiver (purple) and

presented in Figure 3.

Figure 3. HNSE histogram (left). Daily HNSE 95-th

percentile values (right)

These figures confirm that EGNOS SW receiver

provides the best (the lowest HNSE values) accuracy

performances with values about 1m. This EGNOS SW

was developed implementing the receiver

requirements that were considered important for the

future IEC61108-7 standard [1] for SBAS L1 maritime

receivers. Both, EGNOS SW and EGNOS high-end

receiver (HNSE of 0.95m and 1.26m respectively),

provide enhanced position solution with respect to

GPS (HNSE of 2.03m).

EGNOS position availability was impacted due to

the following reasons:

− The coverage area of GEO satellite PRN 120 was

very limited in the Northeast European Area,

which impacted the reception of EGNOS messages

from PRN120 when the vessel was located in the

Northeast area, positions in which the elevation

angle was very low. On 23rd August 2018, PRN

136 was introduced in EGNOS operational

platform replacing PRN 120, which improved the

visibility over the Northeast of Europe.

− In northern altitudes, where the elevation of the

SBAS GEO was very low, EGNOS signal were

blocked in areas close to mountains or fiords.

The impact of the orography in the availability of

the EGNOS signal received by the receiver is greater

according to the elevation angle of the SBAS GEO

satellite as shown in Figure 4. It is noted that the

EGNOS position lower than 100% in locations lower

than 62° latitude degrees was because the vessel was

sailing in narrow fiords with poor SBAS satellite

visibility from the vessel.

Figure 4. EGNOS position availability in function of latitude

obtained from EGNOS Rx.

4.2 Southwest of Europe in 2018 and 2019

The oceanographic Hespérides vessel sailed from

Cartagena (Spain) to Antarctica on 19th December

2018 and returned back on 25th June 2019, covering 48

days inside the EGNOS MT27 service area (longitude

from -40° to 40°, latitude from 20° to 72°). In the return

trip, the ship performed some inspections close to

Canary Islands, being possible to test EGNOS

performance in the border coverage area.

Figure 5 shows the route followed by the vessel

along the mission and the number of days analysed.

Additionally, this figure shows in yellow the vessel

trajectory in which the EGNOS navigation solution

was available with no alarms, after passing the

recommended plausibility checks defined hereafter

and which are included in draft IEC 61108-7 [1]. Then,

a navigation position is considered as valid with no

alarms when the following three conditions

(plausibility checks) are met:

4. SBAS position: The navigation solution using

EGNOS messages have been computed.

5. HDOP check: The Horizontal Dilution of Precision

(HDOP) is equal or lower than 4 (HDOP ≤ 4).

6. Integrity using RAIM: The receiver autonomous

integrity monitoring (RAIM) status is ok, with a

selected accuracy of 10m at the 95% confidence

level, which corresponds to harbour

entrances/approaches and coastal waters [2].

Figure 5.Vessel trajectory through Southwest Europe and

EGNOS navigation solution

As it is observed in yellow, EGNOS navigation

solution was available with no alarms (SBAS position

computed, HDOP check passed successfully and

RAIM integrity algorithm provides a safe status) in

the coastal waters in Europe, covering Canary Islands,

Madeira and South of Spain. As expected, EGNOS

navigation solution (with no alarms) was not available

when getting close to the MT27 area as expected,

especially when located down to 25 degrees North.

Then, the potential SBAS L1 maritime service area for

harbour entrances/approaches and coastal waters

858

could cover in the Southwest of Europe the Canary

and Madeira Coasts.

When computing the percentage of time that the

EGNOS position was OK at receiver level with no

alarms (the three conditions met) for those days in

which the latitudes were greater than 25°, it resulted

in 99.5% for the Maritime SW receiver and 99.7% for

the SBAS receiver. It is noted that these figures are

very good, considering that they were affected by

receiver local effects, such as problems in signal

tracking, gaps in processing or other issues in pseudo-

range measurements.

Figure 6 shows the Horizontal Navigation System

Errors (HNSE) for EGNOS and GPS computed for the

receivers: SBAS High-end Rx and Maritime SW.

EGNOS HNSEs are lower with respect to GPS in all

the cases, meeting with quite margin the 10 meters

requirement for ocean/coastal waters and harbour

entrances/approaches [2].

Figure 6. EGNOS accuracy: CDF figures (left: SBAS High-

end Rx, right: SW Maritime)

Checking the performance per specific days, there

are situations in which position errors are especially

better in EGNOS with respect to GPS. Especially for

areas close to equator in which the ionospheric

activity is high, where EGNOS can monitor the

ionosphere in real time and broadcast up-to-date

corrections, providing more stable accuracy results.

Below an example is presented, in which GPS solution

reached instantaneously the 10-meter error, whereas

with SBAS, the position errors are more stable and

always lower than 4 meters (0.925 meters percentile at

95%).

Figure 7. EGNOS vs GPS: 22/12/2018

4.3 Finnish coast in 2019

The vessel Mastera departed from Porvoo (Finland) to

Primorsk (Russia) then until Naantali (Finland).

Afterwards, the vessel went from Naantali (Finland)

to Primorsk (Russia) being two days stopped close to

Uusimaa waiting for orders (adrift) and finally

arrived at Porvoo (Finland). The total trajectory was

from 1st November 2019 to 14th November 2019.

Figure 8. Vessel trajectory through Finnish coast

Within this GNSS campaign, EGNOS position

availability was 100% for both SBAS maritime receiver

and high-end receiver.

For the EGNOS position accuracy, Table 1 presents

daily HPE (95%) for EGNOS and GPS standalone,

both for High-end and Maritime receivers. It is

noted that for that the GPS position for the high-end

receiver was only available for 5 days, the duration of

the recorded SIS during the campaign. It is observed

that the EGNOS position was always better than the

GPS position. For example: 4.07 m GPS position for

High-end receiver with respect to the 1.18 m for

EGNOS position on DOY (GPS Day Of the Year) 305.

Table 1. HPE (95%) obtained using EGNOS and using GPS

standalone

________________________________________________

EGNOS HPE GPS standalone HPE

95% percentile [m] 95% percentile [m]

________________________________________________

DOY High-end Maritime High-end Maritime

receiver receiver receiver receiver

________________________________________________

305 1.179 0.869 4.073 1.444

306 0.935 0.791 3.284 1.809

307 0.970 0.792 1.653 1.222

308 0.970 0.747 2.103 1.638

309 1.023 0.835 1.738 1.307

310 0.967 0.841 2.235 2.000

311 0.950 0.907 1.832 --

312 0.956 0.718 3.818 --

313 0.873 0.762 3.312 --

314 1.000 0.786 3.527 --

315 1.057 0.808 3.860 --

316 0.911 0.784 1.208 --

317 0.870 0.792 1.228 --

318 1.049 0.872 1.688 --

________________________________________________

TOTAL 0.971 0.815 3.149 1.551

________________________________________________

Additionally, Figure 9 shows the HNSE and ECDF

(Empirical Cumulative Distribution Function) for the

first 5 days where there were results for GPS position.

As it can be observed, EGNOS position errors were

considerably reduced with respect to GPS and the

EGNOS accuracy met with quite margin the 10 meters

requirement for ocean/coastal waters and harbour

entrances/approaches [2].

859

Figure 9. HNSE Histogram for Maritime Rx (left) and ECDF

for both receivers (right)

4.4 Baltic Sea in 2021

Kiisla is a Finnish Aframax crude oil tanker operated

by Neste Shipping. This icebreaking tanker

transported crude oil year-round along the coast of

the Baltic Sea. OSM Group, the Norwegian Oil

Transport provider, manages this vessel. Kiisla,

departed from Munkebo (Denmark) on September 1st

2021 and navigated up to December 1st 2021. The oil

tanker visited eleven harbours placed in five different

countries as seen in Figure 10: Denmark, Lithuania,

Latvia, Sweden and Finland.

Figure 10. Baltic Sea maritime campaign in 2021

EGNOS position availability was 99.99% for the

SBAS maritime receiver. All days presented 100%

EGNOS position availability but one day that was

99.93% due to a local failure at receiver level.

Table 2 shows main statistics for the horizontal

position accuracy when the maritime receiver was

using EGNOS position solution.

Table 2. Horizontal position accuracy obtained using

EGNOS

________________________________________________

EGNOS horizontal accuracy [m]

Period of time (DOY) Mean 95%-percent. Max.

________________________________________________

244 - 253 0.310 0.715 1.168

254 - 263 0.337 0.844 2.350

264 - 273 0.327 0.749 1.145

274 - 282 0.419 0.925 1.829

283 - 293 0.351 0.826 1.447

294 - 303 0.359 0.881 1.730

304 - 313 0.360 0.955 2.068

314 - 320 0.387 0.920 1.617

321 - 335 0.399 0.939 1.466

________________________________________________

TOTAL 0.361 0.779 2.350

________________________________________________

Table 2 presents daily HNSE (95%) quite close to

1m when using EGNOS solution whereas the global

value for the whole data campaign is 0.779m with a

maximum value of 2.35m.

Instantaneous EGNOS horizontal position error is

drawn in the following picture, where it is observed

that EGNOS position met with quite margin the 10-

meter requirement for ocean/coastal waters and

harbour entrances/approaches [2].

Figure 10. EGNOS HPE vs time (left) and EGNOS HPE

histogram & CDF (right)

4.5 Irish coast in 2022

The vessel Granuaile navigated from Killybegs (North

–West of Ireland) on 17th August 2022 up to Dún

Laoghaire on 15th November 2022 (North – East of

Ireland), going between both ports up to Oban (North

England) (see Figure 11). It sailed going in anti-

clockwise direction. The ILV Granuaile is a multi-

functional vessel to maintain the automatic navigation

buoys in Irish waters.

Figure 11. Vessel trajectory through Irish coast

EGNOS position was provided along the whole

trajectory by the maritime receiver during 99.39% of

time. Seven days were identified with EGNOS

receiver position availability lower than 100%, which

were all caused by local issues, such as lack of GNSS

signal, power cut-off and other types of problems at

860

receiver or antenna level. EGNOS system was

available.

Analysing the accuracy results (see Figure 12), it

can be concluded that percentile at 95% of

instantaneous Horizontal Position Errors using

EGNOS is 0.788 meters, meeting with quite margin

the 10 meters requirement for ocean/coastal waters

and harbour entrances/approaches [2].

Figure 12. EGNOS HPE vs time for 23/08/2022 (left) and

EGNOS HPE histogram for all trajectory (right)

5 CONCLUSIONS

This article presents the EGNOS (European

Geostationary Navigation Overlay Service)

performance observed along several maritime

campaigns carried out in European waters with the

objective to demonstrate the availability of corrections

and the suitability of the accuracy to support maritime

navigation. The regions selected correspond to those

located in the border area of EGNOS coverage and

include the following campaigns: Norwegian coast in

2018, Southwest of Europe in 2018 & 2019, Finnish

coast in 2019, Baltic Sea in 2021 and Irish coast in 2022.

Analysing the EGNOS and GPS navigation

position, the main conclusions are the following ones:

1. EGNOS signal in space availability was 100%

during all campaigns meeting the 99.8%

requirement of IMO Res. A.1046 (27) [2]. The fact

that EGNOS system has two operational

geostationary satellites ensures that at least one

satellite is transmitting EGNOS corrections,

providing 100% of EGNOS SIS availability.

2. EGNOS position availability was nominally 100%

in open sky visibility in locations between 25° and

70° degrees latitude.

− In narrow fiords in Norway the SBAS visibility

was blocked, especially in latitudes over 68

degrees where EGNOS satellites were observed

with low elevation. As an example, EGNOS

position availability was 98.5% over the North

of Norwegian coast from 68° to 70° latitudes.

− EGNOS position availability presented high

value above 25° degrees latitude (99.7% for

SBAS High-end receiver), covering navigation

of Canary Islands waters.

− In nominal conditions of open sky visibility

with no issues at receiver or antenna level,

EGNOS position availability was 100%. This

was the case of the Finnish coast campaign.

− EGNOS position availability was impacted in

sporadic moments by local issues at receiver or

antenna level, the observed unavailability

events were not caused by EGNOS corrections.

For Baltic Sea campaign, EGNOS position was

99.99% due to a local failure at receiver level.

For Irish coast trajectory, EGNOS position was

99.39% due to several local issues, such as block

of GNSS signal, power cut-off and other types

of problems at receiver or antenna level. It is

noted that the Irish coast campaign lasted 90

days being more prompt to local problems and

not related to EGNOS SiS corrections

availability.

3. EGNOS position accuracy at percentile 95th was

lower than 2 meters in all the campaigns, meeting

with quite margin the 10 meter requirement for

harbour entrances/approaches and coastal waters

established in IMO Res. A.1046 (27) [2].

− EGNOS position accuracy presented slightly

higher accuracy values over the North border

area and over the Southwest border area,

whereas the improvement with respect to GPS

was bigger and the position accuracy values

were much more stable.

− Apart from navigating close to EGNOS

coverage area, GNSS position performance

was more impacted over those areas due to

ionospheric issues. For example, high-end

receiver presented instantaneous EGNOS

HNSE at percentile 95% during the

Norwegian coast of 1.26m and during the

Southwest Europe campaign of 1.506m,

whereas in Finnish coast was 0.971m.

Additionally, maritime receiver presented

instantaneous EGNOS HNSE at percentile

95% during the Southwest Europe campaign

of 1.061m, whereas in Finnish coast was

0.815m and in Baltic Sea was 0.779m.

− In those areas where GNSS performance is

prompted to be impacted by ionospheric

issues, EGNOS enhancement with respect to

GPS is bigger. EGNOS can monitor the

ionosphere in real time and broadcast up-to-

date corrections, providing more stable

accuracy results. An example is presented

for the 22nd Dec 2018, where there were

peaks of GPS position error up to 10 meters,

whereas EGNOS position remained lower

than 4 meters during the whole day. In this

case improvement of EGNOS with respect to

GPS was quite notably considering that the

HNSE (95%) was 0.925 m for EGNOS and

3.153 m for GPS.

− EGNOS position accuracy at 95% was

nominally lower than 1 meter for both receivers

(Maritime and High-end) in trajectories that

were not located in the border EGNOS

coverage area, such as Finnish coast, Baltic Sea

and Irish coast.

− Position errors using EGNOS were between

30% and 70% better than GPS Standalone

considering the percentile at 95% of the

complete campaign. For specific cases of high

solar activity or ionospheric issues, EGNOS

improvement was considerably important (i.e.

70% for example presented on 22nd Dec 2018)

since EGNOS navigation position was stable

during the whole period whereas GPS

presented important high position errors (even

reaching 10 meters).

861

In consequence, the EGNOS performance observed

on these maritime campaigns indicates that EGNOS

can support “Harbour entrances/approaches and

coastal/ocean waters” according to IMO Res A.1046

(27) [2] over Norwegian coastal waters, Irish coastal

waters, Finnish coastal waters, Canary Ireland coastal

waters and Baltic Sea. Once the IEC 61108-7[1] test

standard on SBAS is published, vessels will start

equipping type-approval receivers using EGNOS

Service and RAIM to ensure a safe navigation in

harbour entrances/approaches and coastal waters.

ACKNOWLEDGMENTS

We would like to express their gratitude to the Norwegian

Coastal Administration for their good collaboration in order

to test the EGNOS performances in the Norwegian coasts.

We would like to thank Hurtigruten Cruises and MS

Finnmarken for letting us use its cruise ship for this GNSS

data campaign.

We would like to express our gratitude to the Spanish Navy

(Armada Española), the Marine Technology Unit, the

Instituto Hidrográfico Nacional (Spanish Navy

Hydrographic Institute), the Programmes Management Vice

Directorate & National Armaments Directorate (Ministry of

Defence of Spain), the Division of Transport Studies and

Technologies & General Secretariat for Transports (Ministry

of Transports of Spain) to allow ESSP to install the receiver

on board this vessel.

We would like to express our gratitude to OSM Group AS

(Norwegian Oil Transport provider) and Väylä (Finnish

Transport Infrastructure Agency) to allow ESSP to perform

this GNSS data campaign in the Gulf of Finland and install

GNSS equipment in Mastera.

We would like to kindly express their gratitude to OSM

Group, the Norwegian Oil Transport provider to allow

ESSP to install the receiver on board this oil tanker, Kiisla, as

well as to Väylä, the Finnish Transport Infrastructure

Agency to invite ESSP to perform this GNSS data campaign

in the Baltic sea and coordinate it with OSM Group.

We would like to thank both Commissioners of Irish Lights

to allow ESSP the installation of GNSS equipment in ILV

Granuaile vessel and GLA (General Lighthouse Authorities)

of the UK and Ireland (Research and Radionavigation

Directorate) for its support in the installation and use of

their MF antenna during the GNSS data campaign around

Ireland.

Finally, the authors would like to acknowledge the efforts

done by EC and EUSPA to work at programme level for the

future provision of EGNOS L1 maritime service.

REFERENCES

[1] Standard under development IEC 61108-7: Maritime

navigation and radio-communication equipment and

systems – Global navigation satellite systems (GNSS) -

Part 7: Satellite Based Augmentation System (SBAS) L1 –

Receiver equipment – Performance standards, methods

of testing and required test results

[2] IMO Resolution A.1046 (27) Worldwide Radio-

navigation System, 20 December 2011.

[3] Transnav Journal: EGNOS Performance Along Finnish

Coast. R. González , E. Lacarra , M. López , K. Heikonen.

DOI: 10.12716/1001.15.03.07