EGNOS positioning in rail domain (ERSAT EAV)

Rodrigo González

ESSP SaS Torrejón de Ardoz, Spain

rodrigo.gonzalez@essp-sas.eu

Gorka de Miguel

CEIT San Sebastián, Spain gdemiguel@ceit.es

Peter Lubrani

ESSP SaS Torrejón de Ardoz, Spain

peter.lubrani@essp-sas.eu

Iñigo Adín

CEIT San Sebastián, Spain

iadin@ceit.es

Jaizki Mendizabal

CEIT San Sebastián, Spain jmendizabal@ceit.es

Abstract—A railway line is characterised through the identification of EMI and GNSS blockers.

Besides, some parameters are defined as key to monitor them in real time. The target of this GNSS

monitoring is to mitigate in advance unavailable GNSS+EGNOS positioning by switching to PVT

solutions which could use different sensors. The original approach in this paper is on one hand, the

use of EGNOS with operational signal for positioning in a true railway and dynamic environment

and on the other hand, the track characterisation when GNSS+EGNOS positioning is unavailable.

Keywords— GNSS, EGNOS, Train Control, Satellite Location, Testing, Railway domain.

1. INTRODUCTION

GNSS-based train localisation has been taking relevancy in the past decade or so

thanks to technological enhancements, GNSS coverage (e.g. EGNOS, GALILEO) and

solution improvement, reflected into various industrial and European/National

important investments into products and concept proofing projects as GRAIL,

GRAIL2, GALEROI, SATLOC, ERSAT, 3inSAT, ERSAT-EAV, etc.

This is in line with the vision of the European GNSS Agency (GSA) and the

European Space Agency (ESA) to “working together with rail and space industry

stakeholders to enable the use of satellite-based positioning for railway signalling, in

order to achieve cost and efficiency benefits, such as the reduction of infrastructure

elements needed for train control systems.” [RD-1]

In particular, the use of EGNOS in the rail domain lies only on the pre-operational

stages of development through different R&D projects.

In such a framework lies the ERSAT-EAV (ERtms on SATellite - Enabling

Application and Validation) project, whose objective is to verify the suitability of

EGNSS (including EGNOS and Galileo early services) as the enabler of a cost-

efficient and economically sustainable ERTMS signalling solution for safety railway

applications. Among the first activities of the above project we find the GNSS

measuring campaign (belonging to WP3). Inside this activity, the ESSP and CEIT

were in charge of identifying GNSS signal blocking signals and their effect onto train’s

PVT solution.

The paper is structured as follows.

Section 2 introduces the main goals of the GNSS data campaign executed on

the Sardinia pilot line.

Section 3 describes an overview of the highest characteristics of the data

campaign.

Section 4 introduces the equipment used during this activity.

Section 5 explains the experimental architecture used for testing as well as the

corresponding test procedures.

Section 6 describes the principal results of EGNOS performance as well as

registry of unknown and known blocking scenarios.

Section 7 presents conclusions.

Finally, section 8 includes prospects for future analysis.

2. OBJECTIVES OF THE GNSS MEASURING CAMPAIGN IN SARDINIA

This paper outlines not only the central objectives of the GNSS data campaign but also

the main outputs that can be extracted from it.

The objective of the data campaign performed between CEIT and ESSP was twofold:

To characterise the Sardinia Trial railway line environment in terms of

unknown blocking scenarios such as electromagnetic interference (EMI) and

known blocking scenarios (natural GNSS blockers) being CEIT in charge of

this part.

To acquire GNSS data both in static and dynamic modes in order to analyse

the GPS only and the EGNOS performance over the Sardinia Trial railway site

(true railway environment) being ESSP in charge of this activity.

3. GENERAL CHARACTERISATION OF DATA CAMPAIGN

The CEIT-ESSP data campaign was performed during five days in the Sardinia Trail

railway site, from 25.01.2016 until 29.01.2016. On the other hand, the ESSP

measurement campaign was carried out only during one day.

General details of the ESSP measurement data campaign are:

• Time frame: 27.01.2016.

• Railway line: Cagliari – San Gavino.

• Dynamic vehicle: Diesel locomotive ALN 668-3114 from Trenitalia.

During this data collection, two types of GNSS measurements were done:

• Dynamic ones: Three return ones because it was a round trip – 9:00-11:00

CET, 13:00-15:00 CET and 16:00-18:00 CET approx.

• Static ones: Five statics: three at S. Gavino and two at Cagliari locations with

different durations depending on the train stop.

1) S. Gavino: 12 minutes, 11 minutes and 13 minutes approx.

2) Cagliari: 58 minutes and 55 minutes approx.

Figure 1: Diesel locomotive ALN 668-

3114 from Trenitalia

Figure 2: Sardinia Trial railway site

4. GENERAL DESCRIPTION OF EQUIPMENT

The ASTS infrastructure in the locomotive was used to connect ESSP and CEIT

equipment. In particular, the antenna was used placed on the train roof. In Figure 3 it

can be seen highlighted in orange the ERSAT Local Determination system (LDS)

whereas Figure 4 and Figure 5 show the antennae’s location.

Figure 3: ERSAT LDS OBU

Figure 4: ERSAT antennae in ALN 668-

3114 (Courtesy of ASTS)

Cagliari

S. Gavino

LDS OBU

Figure 5: ERSAT group of GNSS and communication antenna (Courtesy of ASTS)

Figure 6: ESSP equipment

Figure 7: CEIT equipment (general equipment on the left and Acorde GNSS receiver

on the right-up and GSM/UMTS modem setup on the right-down)

ESSP used part of its laboratory kit in order to perform this activity, a GNSS SiS

recorder and a high-end GNSS receiver, Figure 6.

The set of equipment used to carry out the data collection in the ERSAT pilot line is

presented in the following lines. It is composed of several types of GNSS receivers

which were connected to the already installed antennae in the test locomotive, as

shown in the previous section.

GPS Antennae. Two KATHREIN 870 10003 antennae have been used in

this trial. They can be operated in all frequency ranges between 790 and

2700 MHz; in particular it is used for GPS and 2G/ 3G (communication).

They are Antenna 1 and 3 in Figure 4.

GPS Splitter. The ZAPD-2DC-S+ is a two-way power splitter with SMA

connectors. It is used for GPS signal RF distribution with high

performance. This device feeds DC to the GNSS antenna through port 1. It

is ASTS property.

GNSS SiS recorder (Figure 6). LabSat 3 is a Global Navigation satellite

simulator which allows recording and replaying multi-constellation signals

in L1 band. This device then was used to log GNSS signals, in particular,

GPS, Galileo and SBAS at IF.

High Frequency Digitizer (Figure 7). The high frequency digitizer used

to capture the raw high frequency signals found in the environment of the

GPS and Galileo L1 band is a PXI from National Instruments. This is a

rugged PC-based platform for measurement and automation systems. Each

PXI combines PCI electrical-bus features with the modular, Eurocard

packaging of Compact PCI and then adds specialized synchronization

buses and key software features. The one used in the Sardinia Pilot Line

characterisation is a PXIe-1073 chassis and a PXIe-5162 Digitizer with 1.5

GHz bandwidth, 5 GS/s and 10-Bit.

This digitizer is controlled by a LabView script specifically designed for

that measurement campaign, with a synchronization of the UTC time

(from GPS) with the laptop time and the integration of other data on the

recording.

GSM/UMTS UBLOX Modem (Figure 7). The U-blox EVK-U223

evaluation kit provides environments for evaluating u-blox’ LISA-U230

W-CDMA cellular modules as well as for designing and testing cellular

and GNSS applications.

The modem is connected to the PC with two USB wires. This modem is

capable of recording GSM/UMTS and also giving a GPS position.

The picture shows a portable antenna, but during this measurement

campaign, this has not been used, as the modem has been connected to the

GSM/UMTS antenna already installed on-board.

GNSS receiver (Figure 6). Septentrio AsteRx3-HDC is a multi-frequency

GPS/GLONASS/Galileo/SBAS receiver. This GNSS receiver was used for

two goals:

1) Support activities performed in ERSAT EAV framework such as

monitoring EGNOS performance.

2) Support development of ERSAT-CPS in a multi-frequency and

multi-constellation environment.

GNSS receiver (Figure 7). The Acorde ACGNS-L1 E1-FE-v2 delivers

I/Q data at Intermediate Frequency (IF) and the AGC variable used at

every sample. Both information are given with a rate of 1.5 Hz and stored

in txt format.

Such receiver is complementary to the Ublox and Septentrio receiver data

recording.

Figure 8: ESSP equipment diagram

Figure 9: CEIT equipment diagram

Figure 8 and Figure 9 show the equipment connection in order to perform the

expected activities.

5. MEASUREMENT SETUPS AND TEST EXECUTION

5.1. MEASUREMENT SETUP TO MONITOR AND ANALYSE EGNOS

PERFORMANCE

Figure 6 presents a picture of the setup installed inside the diesel engine during the

measurement campaign at the Sardinia trial site.

A diagram describing the full setup used for this ERSAT activity is presented in

Figure 8.

Two operational chains are connected to the GNSS RF splitter:

The first one shows the GNSS SiS recorder, Labsat 3, connected to the

splitter and it is in charge of recording the GNSS signals, GPS, Galileo and

EGNOS to store them with two main purposes:

1) if it had been needed, to reproduce them in other GNSS receivers

in ESSP premises;

2) to store these signals just in case any kind of anomaly had been

detected: interference, EMI or EGNOS underperformance.

The second chain represents the one which was recording the GNSS

information to get the dynamic position using EGNOS only. Besides, the

outputs of the Septentrio AsteRx3 supported the interference analysis.

5.2. TEST PROCEDURE TO MONITOR AND ANALYSE EGNOS PERFORMANCE

Each chain shown in Figure 8 has a different procedure to record the appropriated

data.

For the first chain, the GNSS signal recorder was used to have data of two returns

journeys (13:00-15:00 and 16:00-18:00).

The second chain firstly needed a time for the GNSS receiver to start and get the

position, afterwards, it was configured to have data from Galileo, GPS and EGNOS as

well as to consider EGNOS SoL Precision Approach according to a MOPS compliant

receiver1.

It has to be noticed that for the first return journey, the GNSS splitter was connected to

the Antenna 3 (from Figure 5) and for the rest, the Antenna 1 (from Figure 5). It made

to have a higher antenna gain, 5 dB, due to this change of connection (see Figure 19).

5.3. MEASUREMENT SETUP TO DETECT UNKNOWN BLOCKING SCENARIOS

(EMI)

Figure 7 presents a picture of part of the setup installed inside the locomotive during

the measurement campaign at the Sardinia trial site. This includes the test setup to

determine unknown blocking scenarios as well as the test setup to identify the natural

GNSS blockers. All the communication devices, cables, connectors, etc. are inside the

box, but this picture shows the high speed digitizer and a print screen of the Labview

script dedicated to the recording of the raw data for the matter of that section. The

complete block diagram of the test setup used is presented in Figure 9.

Two chains are here represented. The one connected to the GPS antenna is in charge of

the recording of the interferences around the GNSS frequency band. The one

connected to the GSM/UMTS antenna is recording the observables of the GSM and/or

UMTS bands shared by the Base Stations with the modem.

The first chain has been designed and implemented to record the interfering signals

present in the frequency band around the GPS band in order to evaluate their influence

in the GPS availability. For that, the high speed digitiser and the Acorde AGC monitor

were connected and synchronized. A script designed in Labview was used in order to

establish the same time reference for both subsystems. The raw interfering signals can

be recorded in two different ways; continuously every some specified seconds or when

a trigger happens. In the Sardinia trial site measurement campaign both approaches

were used.

The second chain is helpful for determining the interferences affecting the voice and

data communication systems at the Sardinia trial site during this measurement

campaign. The GMS/UMTS modem already presented is the one in charge of the

UMTS/GSM observable recordings. In that case, the modem establishes the

communication with the surrounding base stations and the data received were

recorded.

5.4. TEST PROCEDURE TO DETECT UNKNOWN BLOCKING SCENARIOS (EMI)

Both chains presented in Figure 9 have their own test procedures in order to start up

and to record the appropriate data for each moment and location.

1 As there is a lack of railway user’s requirements at GNSS performance level, it has been considered one GNSS

receiver assuring the equipment will perform its intended function(s) satisfactorily under all conditions normally

encountered in routine aeronautical operations according to RTCA Minimum Operational Performance Standards, DO-

229.

For the first chain, at the beginning of every journey, the Acorde AGC monitor needs

to be switched on in order to obtain the standstill value for that moment and the

conditions surrounding, when GPS is able to fix the position. With this AGC gain

value, a threshold is defined, 3dB margin for this case2. The recording of the data is

done every time the GPS signal has a significant variation from the standstill

conditions. Once connected to the high speed digitiser, by means of the Labview script

on the laptop, every time the AGC gain reaches the trigger levels, the high speed

digitiser records the raw signals captured at the GPS antenna with the following

characteristics and format:

5 Gsamples /s.

1Msample word (equivalent to 200us).

Percentage of backward recording (customized at the Labview script).

HWS format (NI proprietary) with a0 and a1 coefficients depending on the

amplitude range expected at the input of the high speed digitizer (defined

at the Labview script).

The other implementation for that data recording is applied with no triggers. In that

case, the signals captured by the GPS antenna are recorded continuously for the entire

journey. The number of files that can be saved per second depends on the availability

of the communication link (PCI Slot).

The second chain needs to be synchronised to the same time reference by means of the

GPS signal. At the start up, the GSM/UMTS observables recording application needs a

UTC time provided by the embedded GPS receiver to its module. Once the time is set,

the application switches to the data obtaining using the AT commands CGED. The

Base Station connected to the GSM/UMTS modem sends back the following

information: Date and Time, Cell Type, Mobile Country Code, Mobile Network Code,

Location Area Code, Cell Identification, Received Level and Timing Advance.

6. RESULTS OF MEASUREMENT CAMPAIGN

The pilot line where the GNSS Measuring Campaign was performed is placed in an

open-view-sky area; rural environments with some industrial facilities not so high and

several bridges.

Figure 10: General landscape in Sardinia trial site

2 This value implies that the AGC introduces a gain that is half the needed when GPS is working at open sky and

standfills operation.

Figure 11: General obstacles in Sardinia trial site

Figure 10 and Figure 11 can be representatives for the expected environment in the

test site. These support the hypothesis of a “friendly” environment for EGNOS

positioning tests in rail domain.

6.1. RESULTS OF EGNOS PERFORMANCE

Once the GNSS data were processed, they were compared with the computed ground

truth (obtained with the same antenna) in order to have the horizontal accuracy for

each test. This ground truth was provided by Radiolabs.

The creation of the ground truth was performed by RTK algorithm. As “Base Station”

it was chosen reference stations from ItalPos augmentation network (http://it.smartnet-

eu.com/) located in Sardinia and specifically Cagliari and Senorbi.

It was used both reference stations for runs from Cagliari to San Gavino and vice versa

while for static positioning, the nearest reference station.

A first stage of the EGNOS performance analysis is to compute EGNOS Precision

Approach (PA) availability, [RD-2], which is an indication of the ability of the system

to provide usable service within the specified coverage area under defined user

requirements of integrity. This is a first approximation based in aeronautical domain

because of the lack of GNSS user requirements for railway domain. However, the

European GNSS Secretariat – European GNSS Rail Advisory Forum included an

optimistic viewpoint that a railway system may efficiently benefit from the use of

satellite technology, [RD-3]. Considering that purpose, a list of some GNSS user

requirements was created for safety related applications in railway domain as shown in

Table 1.

It has to be clarified that the stressed operations in Table 1 with an orange rectangle

correspond to the Safety related applications; the green one to the Mass commercial/

Information and management – operational applications and the blue one to

Infrastructure ¬ Civil engineering/ professional applications. Moreover, the results in

this paper are focused on safety-related applications, in particular in Train Control on

medium and low traffic density lines.

In addition, Table 1 reflects requirements related to information at the output of a

location unit, which is defined as “a device that fulfils specific functions for location –

basically the provision at the device's output interface of information on position and –

if necessary - other information, for example: speed, direction of movement and

acceleration”, [RD-3]. Although GNSS positioning cannot be used as stand-alone

technology, this document is focused only in the EGNOS.

Table 1: Contemplated GNSS railway user requirements [RD-3]

Because of this, the aeronautical standards can be considered as a preliminary

approach. Protection Levels are taken as GNSS parameter for this performance

analysis and in particular the Safety-of-Life service Precision Approach is considered

for the analysis.

The first row of Table 2, “number of unavailability periods≤ 10s”, includes all the

periods where there was no EGNOS PA (Precision Approach) signal or with

Horizontal error over 6 m during less than 10 seconds. The second one, “number of

unavailability periods between 10s and 20s”, includes all the periods where there was

no EGNOS PA signal or with Horizontal error over 6 m in that period. The third row,

“number of unavailability periods> 20s”, includes all the periods where there was no

EGNOS PA signal or with Horizontal error over 6 m during more than 20 seconds. The

“total duration of unavailability for each trip” is the sum of the time when EGNOS PA

signal is not available for each dynamic test. The penultimate one, “PA availability for

each trip”, is the percentage of PA availability considering the three return trips and the

last one is the EGNOS PA availability taking into account the three Cagliari-S. Gavino

trips and vice versa.

The figures 01, 02 and 03 present in Table 2 indicate the order of the sequential test in

each direction.

Cagliari – S. Gavino S. Gavino - Cagliari

Number of unavailability

periods ≤ 10s

01 13 20

02 24 22

03 15 11

Number of unavailability

periods between 10s and 20s

01 0 0

02 0 0

03 1 (15:19:15-15:19:25) 0

Number of unavailability

periods > 20s

01 0 0

02 1 (12:17:30-12:17:54) 0

03 0 0

Total duration of

unavailability for each trip

01 19s 36s

02 86s 39s

03 34s 13s

PA Availability for each trip

01 99.435% 98.689%

02 97.360% 98.724%

03 98.990% 99.580

Total PA Availability 98.608% 99.011%

Table 2: EGNOS PA Availability in return trips

Table 2 highlights the fact the trial line was in a rural environment with almost an

absence of GNSS blockers with the only exceptions of bridges. Because of that, the

global PA availability on the Sardinian trial is 99.199% (considering 7 hours 52 min and

27 s).

Figure 14 and Figure 15 show how a good level of accuracy, almost below 4 meters, is

obtained in all return journeys. The only rejected points have been those when the

locomotive was passing through bridges being the only impact a higher horizontal

accuracy error, between 6 and 15 meters, during less than 10 seconds; because of that,

those withdrawn events have a negligible impact on the PVT solution on the test site.

Figure 12: HPL in trip Cagliari - S. Gavino

Figure 13: HPL in trip S. Gavino – Cagliari

It has to be noted that the majority of the HPL values over 20 meters correspond to the

passage below bridges.

Figure 14: Horizontal Accuracy in trip Cagliari - S. Gavino

Figure 15: Horizontal Accuracy in trip S. Gavino – Cagliari

Figure 16: Horizontal Accuracy during the complete measurement campaign

When the train passed below a bridge, the EGNOS Horizontal Accuracy values increase

over 6 meters up to 17 meters as maximum value during one or two seconds.

In three occasions some buildings affected this parameter the same way as

aforementioned:

Train stations: Serramanna (along C-SD-01 during 119s and C-SG-03

during 9s) and Elma (during 23s along SG-C-01).

Industrial facilities: Between Samassi and Serramanna (along SG-C-03

during 37s).

Rural area when Samassi is passed (during 74s along SG-C-03).

Figure 17: Horizontal Accuracy – withdrawn areas

This asymmetric impact in the same area for different runs has a geometrical

explanation: GPS constellation is not the same for each trip.

To have representative EGNOS Horizontal Accuracy values, those figures between 6

and 17 meters have been deleted from Figure 14, Figure 15 and Figure 16. Thanks to

that, it can be assumed a more realistic value for this parameter whose average is 1.5

meters approx. because those withdrawn events had a negligible impact on the PVT

solution during the tests.

6.2. RESULTS OF UNKNOWN BLOCKING SCENARIOS (EMI)

After the test setup, it is verified that AGC values do not reach the defined threshold

(3dB margin) as seen in Figure 18 (AGC from Acorde GNSS receiver) and Figure 19

(AGC from Septentrio GNSS receiver).

Figure 18: Acorde AGC gain plot along a complete day

Figure 19: The Septentrio AstRx3 AGC gain plot along a complete day

Both plots present no major changes in the gain for any of the journeys recorded on the

same day, even if the connection to the GPS antenna was changed at 11:45 to evaluate

the performance of both GPS antennas installed on-board (Figure 19). Neither was it

shown by Septentrio AsteRx3’s GNSS receiver. The AGC gain used to trigger the high

speed digitizer was the one shown in Figure 18 and consequently, no significant

transients were found on the L1 GPS frequency band during this measurement

campaign with that test setup and test procedure. Figure 19 validates that conclusion.

The good conditions for GNSS solutions in the Sardinia trial site made this trigger

almost useless, so a continuous recording of the raw signals was also done during

further journeys in order to have a view of the spectrum all over the track.

Figure 20 and Figure 21 show the time-based representation of some of the most

powerful signals (interferers), in dBm, extracted from the complete set of signals

recorded by the high speed digitiser. Figure 21 is a zoom where some of the most

significant signals are plotted. Some of them start during the recording, which means

that this kind of communication could be not permanent. That point is coherent with

the observation by CEIT inside other research projects on a similar matter [RD-4].

Figure 20: Interface signals maximum power recorde

Figure 21: Interference signals maximum power recorded - some significant transients

depicted

Figure 22 shows a merge representation of the time-frequency analysis done to the raw

transients extracted from the continuous recording into one single plot. It is clear that

the GPS L1 band is not impacted by any kind of interference signal. The GSM, the

UMTS and the Italian 4G bands are the ones showing the higher powered signal at the

antenna connected to the high speed digitizer (around 800MHz-900MHz, 1.8GHz and

1.9GHz). It has to be highlighted that the 1.25GHz frequency is also significant in that

plot due to the down sampling operation of the digitiser.

Figure 22: Time-Frequency plot of the continuous recording of signals

6.3. RESULTS OF KNOWN BLOCKING SCENARIOS (NATURAL GNSS BLOCKERS)

From the Sardinia trial site point of view, the only known blockers found in the

Sardinia pilot line are the motorway bridges and other roads crossing the tracks.

However, they were not wide enough to make the GPS receiver lose the position. The

power received from the GPS satellites decreased during the time that the antenna was

under the bridge, but its duration was not enough to lose the communication with the

satellites. Nonetheless, the average SNR received from the satellites decreased

considerably, converting it into a good indicative (trigger) to start the performance of a

Complementary Positioning System (CPS).

Figure 23: GPS satellites available and their SNR power before and under a bridge

Figure 23 shows two moments of the first journey analysed. The upper one is just

before the train going under the bridge. Eight GPS satellites are available to fix the

position with high SNR values (Green bars in the graph) around 40dB. In the lower

one, the train is just under the first bridge. The same eight satellites are available to fix

the opposition, even if their SNR is 25dB lower, in average, so the position is fixed.

That is a pattern that is repeated in every significant GNSS blocker found on the

Sardinia trial site and used as a trigger for the CPS Known Blocking Scenarios

Algorithm.

7. CONCLUSIONS OF THE GNSS MEASURING CAMPAIGN

The results show that the only effects seen by the GNSS receiver are due to overhead

infrastructures ,obstructing by larger objects, such as bridges (see left picture from

Figure 11), cornices of the train stations (see right picture from Figure 11) and not

very tall buildings. These obstructions may be due to the physical size but the limited

time noted for the high values of EGNOS HPL and Horizontal errors require further

investigation.

This worsening of performances could be reduced when the future satellite-based

system, Galileo is used, as the number of available satellites would be much more.

This would increase availability for more enclosed areas, but tunnels and bridges

would still need to be accounted for.

On the other hand, it has to be highlighted the fact of getting a good EGNOS Accuracy

during the dynamic tests. These results may support future analysis and help in the

development of specific user requirements in the rail domain such as establishing a

Horizontal Alert Limit or a percentage of availability.

Complementary conclusion of this data campaign is that some GNSS performance

parameters can be monitored in order to guarantee that the signal from GNSS satellites

is correctly received. Nonetheless, a unique parameter to monitor GNSS blocking

cannot be established therefore: AGC value from GNSS and EGNOS satellites could

be complemented by others such as SNR for GNSS constellation and EGNOS and

HDOP. The detection or not of one or both of the EGNOS operational GEO satellites

(PRN 120 and PRN 136) is another parameter that could be proposed to identify

natural GNSS blockers. The main purpose of monitoring GNSS performance is to

combine PVT solutions obtained with GNSS with PVT solutions from other alternative

systems in order to guarantee a global solution.

8. OUTLOOK

One of the main issues encountered in this measuring data campaign was the lack of

multipath evaluation of standard scenarios, including the train stations. They could be

carried out in order to collect sufficient exposure to individual satellites for a full

multipath examination to be performed.

Future work for CEIT and ESSP’s is to validate these conclusions obtained in the

Sardinia pilot line in different environments where GNSS blocking elements are

present.

ACKNOWLEDGEMENTS

This research was supported by the ERSAT-EAV project as part of the European

H2020 framework of projects funded by the European Commission (EC) and managed

by the European GNSS Agency (GSA).

We thank our colleagues from ASTS and RFI who allowed both measuring campaigns

in the project’s framework and the use of their infrastructure. They also coordinated

with Trenitalia the use of their locomotive.

We also thank our colleagues from RadioLabs who computed the Ground Truth carried

out during this GNSS data campaign.

We would also like to show our gratitude to the personnel of Trenitalia both on board

and at the station for their support.

REFERENCES

[RD-1] Statement by the GSA https://www.gsa.europa.eu/newsroom/news/e-gnss-

enabled-railway-signalling-%E2%80%93-vision-action.

[RD-2] EGNOS Safety of Life Service Definition Document.

[RD-3] Requirements of rail applications. GNSS Rail User forum. May 2000.

[RD-4] Cross acceptance EMC test sites, test setup and test procedures specifications.

Deliverable TREND project 30.04.2014.

[RD-5] ERSAT EAV Grant Agreement Nº 640747.