galileo - institute of photogrammetry and remote sensing

GalileoIllustration: ESAIllustration: ESA

Professor Terry Moore

Professor of Satellite Navigation

Nottingham Geospatial Institute

The University of Nottingham

© 2011 NGI

Lecture Contents

• Overview

• Services

• Satellites & Orbits

• Ground Segments (Mission, Control)

• Signals

• Status & Plans

• Institutional & financial aspects

© 2011 NGI

Global, European-led under civil control

Independent but compatible & interoperable with GPS

A variety of services are planned

GalileoEuropean Satellite Navigation System

No. of satellites 30 MEO

Constellation 3 planes, 120°

Altitude 23222 km

Inclination 56°

Ground repeat 10 days

© 2011 NGI

-Critical Infrastructure (dependence on GPS)-European independence and sovereignty-Civil controlled-A key enabling technology for EU competitiveness

Political

Social Technological

GalileoWhy do we need Galileo ?

-Transport infrastructure overload-Better & new services for citizens- Improved safety of transport- Environmental benefits

- Global market shares- Global competitiveness of all segments of the Value Chain- Employment- Efficiency of transport & other industries

-Technological lead to European industry-Not a high technological risk

Social

Economic

Technological© 2011 NGI

Galileo System Architecture

Users

Satellites

Navigation &Integrity UplinksSatellite

controlTT&C

Sensor stations

Comms Networks

Control &Processing

Centres

© 2011 NGI

User Segment

• Galileo developments includeddevelopment of a Test User Segment– to prove system function and performance

– to facilitate testing and “tweaking” of thesystem prior to declaration of operational status

• Second strand of User Segment

Users

• Second strand of User Segmentdevelopment is to support & encourage:– Receiver manufacturers

– Application developers

– And ..... End Users

• to include Galileo and its benefits in their:– Designs

– Standards

– Future operations plans

© 2011 NGI

Sensor Station (GSS)

• Globally distributed network of sensor stations

• GSS includes reference-grade Galileo receiver

• Each GSS simultaneously monitors 8-10 satellites

• Each satellite is simultaneously monitored by 8-10 GSSstationsstations

• All measurements relayed to GCC over Comms links

Sensor stations

© 2011 NGI

Control and ProcessingCentre

• Receives Satellite measurements from GSS Network

• Orbitography processing derive Orbits & Clocks

• Integrity Processing derives Integrity confirmation (& alerts)

• Relays uplink data to satellites via networks of TT&C andUplink stationsUplink stations

• Two parallel facilities at different locations in Europe forrobustness

Control &Processing

Centres

© 2011 NGI

TT&C Stations

• TT&C (Telemetry Tele-command and Control Stations trackand control satellites via uplinks

• Encryption for asset protection

• Five globally distributed stations facilitate almostcontinuous connectivitycontinuous connectivity

• TT&C interconnected to GCC by Comms network

Satellitecontrol

TT&C

© 2011 NGI

Navigation & IntegrityUplink Stations

• Smaller stations that TT&C, but more of them

• Uplink data to satellites for inclusion in Navigationdownlink– Navigation data

– Integrity

• Encryption for asset protection• Encryption for asset protection

• 12 globally distributed stations facilitate continuoussatellite connectivity

• ULS interconnected to GCC by Comms networkNavigation &

Integrity Uplinks

© 2011 NGI

CommercialService (CS)

Galileo Services

Open Service (OS)

Search and RescueService (S&R)

Public Regulated Service (PRS)

Safety-of-LifeService (SoL)

© 2011 NGI

Services DetailsOpen Service(s)

• Market: Mass-market users, and indeed anyapplications not needing other services

• Worldwide coverage

• Free of Charge

• Performance similar to (future) GPS• Performance similar to (future) GPS

• Operable single or dual frequency

• Dual-freq accuracy: ~7m Horizontal 2D, 95%

• No integrity

• No guarantees

• Substantial effort exerted to optimise interoperabilitywith GPS

© 2011 NGI

Services DetailsCommercial Service(s)

• Market: Professional applications


• Performance based on OS, but ...– Enhanced accuracy, integrity, availability

• Third frequency to facilitate TCAR• Third frequency to facilitate TCAR– Triple Carrier Ambiguity Resolution

– Rapid-resolution of ambiguities for cm-level accuracy

• Encrypted data

• Potential for differentiated performance indifferent geographic areas

• (Optional) inclusion of integrity data

© 2011 NGI

Services DetailsSafety of Life Service

• Market: Safety of Life / IntegrityApplications


• High Accuracy, High Integrity– (see table)– (see table)

• Protected ARNS Bands

• Degraded (fallback) modeon single frequency

• Encrypted authentication TBC

• No direct charges

Horizontal accuracy 6 m (95%)

Vertical accuracy 8 m

Velocity accuracy < 0.20 m

Timing accuracy <100 ns

Continuity risk <10-5 per 150 s

Integrity Risk <3.5 10-7 per 150 s

Integrity TTA 6 s

Horizontal alarm limit 11 m

Vertical alarm limit 15 m

Availability 99.9 %

© 2011 NGI

Services DetailsPublic Regulated Service

• Market: Security services– Police, customs, critical infrastructure, military(?)


• Independent frequencies

• Performance similar to OS/ SoL• Performance similar to OS/ SoL

• Restricted user groups

• Controlled access

• Service robust to denial of other services

© 2011 NGI

No. of satellites 30 (inc.3 spares)

Constellation 3 planes, 120°

Altitude 23222 km

Inclination 56°


Galileo ConstellationPlanned FOC configuration


Orbital period 14:15 Hrs(5 orbits / 3 Sidereal days)

Satellites transmit continuous ranging codes & navigation data

Ground contact once per orbit for upload of S/C commanding &monitoring (S-Band)

Timing parameters, Navigation data and Integrity data up-linked continuously by dedicated ground stations (C-Band)

© 2011 NGI

Galileo and GPS

Galileo GPS

Satellites 27+3 24 (32!)

Planes 3 6

Sats per plane 10 4-7

Plane Spacing 120o 60o

Higher Galileo orbit coupled with inclination increase give bettercoverage at high latitudes

Inclination 56o 55o

Orbit type MEO Circular MEO circular

Orbit Radius 29,500km 26,500km

Period 14¼ hour 12 hour

Sat ground track repeat 10 days 1 day

© 2011 NGI

Galileo ConstellationIllustration: ESA

© 2011 NGI

Galileo SpacecraftFunctional Architecture

P a y lo a d

P o w e rS /S

S tru c tu reS /S

P o w e r I/F

S ig n a l I/F (c m d , d a ta , a n a log , ...)

Inte

gri

ty

In te g D e c

H a rn e s s n o t s h o w n

A v io n ic sS /S

(IC D S )

T T & CS /S

P ro p u ls io nS /S

D is p e n s e r,P y ro s

S /S

R a n g in gS /S

T h e rm a lS /S

U m b . P o w e r

D e c /E n c

TC

/Nav

TM

Inte

gri

ty

S ta tu s

L a u n c h e r I/F

P y ro C m d

U m b ilic a lP o w e r

S ta tus &© 2011 NGI

Galileo PayloadFunctional Breakdown

• Reference Clock generation

• Generative payload providing L-Band navigationservices– Reception & storage of up-linked Navigation and Integrity data

– Security on Mission data uplink and PRS signal– Security on Mission data uplink and PRS signal

– Generation of ranging codes

– Assembly of navigation message in the defined format

– Broadcast of navigation signals at the defined frequencies andpowers

• Search and Rescue Transparent Transponder

• Control and Monitoring of Payload, and interface to thePlatform

© 2011 NGI

Galileo PayloadFunctional Breakdown

© 2011 NGI

Galileo Ground Segments:

- Mission (GMS)- Control (GCS)- Control (GCS)© 2011 NGI

Ground Mission SegmentOrbit Determination and TimeSynchronisation System (ODTS)

• Globally distributed network of monitoring stations

• Measure pseudo-ranges using code & phase tracking

• Each station can monitor up to 12 satellites in parallel

• A minimum of 3 monitoring stations, with accurately knownlocations, are needed to fix the satellite position, 4 forposition and clock (satellite) corrections.position and clock (satellite) corrections.

• Measurements are pre-processed and sent to a processingcentre where the ephemeris (orbital position) and clockcorrections are computed

• Ephemeris and clock corrections are uplinked to thesatellites via a network of uplink stations

© 2011 NGI

Ground Mission SegmentODTS Architecture

Rubidium andPassive H-maser

clocks

ULS

GSSAtomic clockdata

PTS (x2)4 Caesium clocks

2 H-maser

UTC(k) laboratory

Timesteeringto UTC

ODTS

Ephemeris& ClockPrediction

GSTdefinition

OSPF

ULS© 2011 NGI

Main Steps in ODTS

1. Orbit prediction by numerical integration of the equations ofmotion over a given time

2. Computed tracking observations constructed numerically fromknown station position and the satellite positions fromintegrated orbit

3. Differences are computed between the tracking observationsand the calculated values from the orbital model. –and the calculated values from the orbital model. –measurement residuals

4. Least squares estimation of corrections to various modelparameters

5. Entire process iterated until the desired level of precision isreached

ODTS processing

One-waymeasurements

Met data

Dynamicalmodels Ephemeris

prediction andclock correction

© 2011 NGI

Ground Mission SegmentGalileo Integrity

• The Galileo Ground System monitors Galileo Satellitetransmissions for Integrity

• If any out of tolerance conditions are detected, theGalileo System alerts users of the Integrity problem

• The alerting mechanism uses the normal (SoL)• The alerting mechanism uses the normal (SoL)navigation transmissions to communicate to users– Galileo SIS include Integrity confirmation & Integrity Alerts

• Alerting has to be done within a defined time to alert(TTA) limit

© 2011 NGI

All Satellites

• Set satellite Health Flags• Incorporate SISA and satellite

Health Flags into navigationsignals

Selected DisseminatingSatellites

• Collect Integrity Messages• Incorporate Integrity Messages

into Navigation signals


ODTS

• Compute SISA• Upload SISA

IDS

• Validate Satellite Health Flags• Perform SISA Independent Check• Compose Integrity Message• Upload Integrity Message

C-band Nav.U/L Nav. D/L signals C-band Integrity U/L© 2011 NGI


GCC

GSSIntegrity Data

IPF

ULS

© 2011 NGI

Integrity Principles

• Observe every satellite with a sufficient number ofmonitoring stations

• Pre-process the measurements for– troposphere propagation

– ionosphere propagation

– multi-path detection– multi-path detection

• Exclude monitoring stations with high multi-path,troposphere or ionosphere activity on a per satellite basis

• Flag satellites as bad, for which the difference between thecomputed and corrected measured pseudo-range is ofstatistical relevance for at least one monitoring station.

• Uplink the integrity message to the satellites forincorporation into navigation message

© 2011 NGI

Partitioning of IntegrityBetween System and User

• System provides timely warning if the errors caused by

– Satellite

– Clock

– Signal

– Navigation message

… are larger than threshold value… are larger than threshold value

• User has to assess all the hazards on the

– signal propagation path and

– all local effects

… by using redundant signals & signal quality measures(e.g. using Receiver Autonomous Integrity Monitoring)

© 2011 NGI

Galileo Ground ControlSegment (GCS)

• The GCS provides for all classical satellite controlTelemetry, Tracking and Commanding (TT&C)functions of the 30 MEO satellite constellation

• Functions are implemented via a Satellite ControlFacility (SCF) located at a Galileo Control CentreFacility (SCF) located at a Galileo Control Centre(GCC) distributing and receiving data to theconstellation of satellites via 5 globally distributedTT&C stations

• Data communication with these remote TT&C stationsfrom the SCF is via a dedicated Data DistributionNetwork

© 2011 NGI

GCS Architecture

GCC

SCCF

TT&C TT&C

Etc.

comms comms

© 2011 NGI

Galileo Ground SegmentRationale for Site Locations

• Geographical locations based upon European or friendly nationterritories utilising existing facilities with communications networks

• Galileo Sensor Stations (29+)– These are receiving stations for reception of the 4 L-Band signals

– The number of these stations has been defined according to the needs ofIntegrity and ODTS

• TT&C stations (5)• TT&C stations (5)– Five global locations required to provide routine TM&TC operation and to enable

near constant contact with the constellation in case of emergencies

• Mission uplink stations (Navigation & integrity) (10)– Locations defined to ensure up-link of integrity to a subset of S/Cs visible by

users with a masking angle >25°

– Navigation uplink required every 100 minutes to all satellites for clockcorrections

– Continuous uplink of Integrity data

© 2011 NGI

GalileoOverall Ground Architecture

MCF

(IMC)

GCC-1 (GCC-2)

5 S-band TT&C sites(13m dish, 1 dish per site)

co-located with 5 GSS and5 C-band U/L stations

Geo

gra

ph

icallin

k

19 Galileo Sensor Station (29 total)3 RX chains per GSS (NAV + INT + Backup)

DOC5 + redundancy

SCF

(IMC)

PTF

IPF

OSPFSPFGACF

5 C-band U/L stations (10 total)(3.0m dishes, 4 dishes per site)

co-located with 5 GSS

EXTERNAL INTERFACES

Geo

gra

ph

icallin

kLAN

LAN

© 2011 NGI

GalileoGround Segment Sites

Kiruna

Svalbard

Redu

Fucino

StPierre&M.

Az/CanUSNO

Hawaii Riyadh

S.Korea

Wainwright

GSS

GSS + ULS

GSS + ULS + TTC

KourouUnder FOC procurement

FOC contract awarded

Papeete

Réunion

IOV contracts/ATP

Troll

Noumea

Ascencion

Kerguelen

Cordoba South Africa

Hawaii Riyadh

Easter IslandPerthHartebeesthoek

Note: other potential sites are under consideration for FOC, incl. Falklands,Terre Adélie, Jan Mayen, Reykjavik, Diego Garcia, Guam

© 2011 NGI

GalileoIOV Ground Segment Sites

Kiruna Galileo TTC Site Completed (Nov 2007)Kiruna Galileo TTC Site Completed (Nov 2007)

Svalbard Galileo ULS/GSS Site Completed (May 2008)

© 2011 NGI

GalileoGround Control Centres

OberpfaffenhofenCredits:

Fucino(Italy)

Oberpfaffenhofen(Germany)

Credits:ESA

Credits:ESA

Credits:ESA

© 2011 NGI

GNSS-Frequency Bands

GPS GLONASS

1240 12561260 1300 MHz

E6

12171164 1188

E5BL5 L2 G2

GALILEOGALILEOGPS/ GALILEO

E5A

E1E2 G1L1 C1

GPS/ GALILEO GLONASS

1563 15871593

1610 MHz1559

G1L1

5030 MHz5000 5010

Uplink

406.0-406.1MHz

DistressUplink

1544.05-1544.15MHz

SAR-Fwd-downlink

GALILEO - SAR

E6-(A): -155dBW

E6-(B): -158dBW

E6-(C): -158dBW

L1(A): -155dBW

L1(B): -158dBW

L1(C): -158dBW

E5a-I: -158dBW E5b-I: -158 dBW

E5a-Q: -158dBW E5b-Q:-158 dBW

On-Ground Galileo Power

© 2011 NGI

Galileo Signals

© 2011 NGI

Impacts of GalileoSignal Design

• Improved acquisition & tracking

• Improved multipath performance

• Improved building penetration

• Through implementation of various signal features:– Wider bandwidths

– More frequencies

– Improved BOC modulation schemes

– High chip rate

– Improved codes

– Pilot tone

• And dual (multiple) civil frequencies permitting mitigationof ionospheric uncertainty & supporting CP Ambiguityresolution

© 2011 NGI

GalileoImplementation Steps

In-Orbit Validation4 IOV satellites plus ground segment

Initial Operational CapabilityEarly Services for OS, SAR, PRS

18 satellites

2014

Full Operational CapabilityAll services, 30 satellites

2019/2020

Galileo System Testbed v1Validation of critical algorithms

2003

Galileo System Testbed v22 initial test satellites

2005

2012© 2011 NGI

Galileo Development & Test

• Concept, Mission Definition, System, Subsystem andElement Studies, Specifications, Design,Developments, Test, Validation, Verification– ~1999 -> ~2011

– Completed– Completed

• GSTBV1 – Galileo System Testbed v1– Validation of critical algorithms

(included use of GPS measurements!)

– Completed 2004

• GSTBV2 – Galileo System Testbed v2– Initial Galileo satellites (also called GIOVE)

• A - launched Dec.2005 (still operating)

• B - launched April 2008 (still operating)

© 2011 NGI

GSTB-V2 / A Giove-A GSTB-V2 / B Giove-B

Galileo System Test BedSatellites

• Lift-off mass 450 kg

• Power demand 600 W

• Stowed Dimensions1.3 m x 1.74 m x 1.4 m

• Lift-off mass 523 kg

• Power demand 943 W

• Stowed Dimensions:0.955 m x 0.955 m x 2.4 m

© 2011 NGI

Galileo IOV

• Full-scale hardware & software development and deploymentleading to qualification of Space, Ground & User segments

• Limited constellation (4 satellites)

– First 2 satellites scheduled to be launched from Kourou (FrenchGuiana) 20 October 2011

– Next 2 IOV satellites for launch 2012

• Limited capability Ground Segment largely deployed and• Limited capability Ground Segment largely deployed andcommissioned

– Two Ground Control Centres (GCC) working in ‘Split GCC’ mode

• Fucino (Italy) GCC – host and operate the GMS (Mission Segment)

• Oberpfaffenhofen (Germany) GCC – host and operate the GCS (ControlSegment)

– A network of sensor stations providing coverage for orbitography andsynchronisation measurements

– A network of uplink stations providing uplink of the navigation data

– Two TT&C stations providing control of the constellation

– A global data dissemination network to interconnect the groundfacilities

© 2011 NGI

Galileo IOV Satellites

• Galileo IOV Satellites– Galileo final design Satellites

• Payload includes– complete & final navigation chain

• generation and broadcast of various• generation and broadcast of variousGalileo in L-band navigation signals

– Clocks

• 2 rubidium atomicclocks

• 2 passive hydrogenmasers

• Mass Approx. 700 kg

• Size (1) 3.02 x 1.58 x 1.59 m

• Size (2) 2.74 x 14.5 x 1.59 m

• Design lifetime 12 years +

• Available power 1.420 W (sunlight)

/1.355 W (eclipse)

• Nav P/L power 780 W

• SAR P/L power 100 W

(1) solar array stowed; (2) solar array deployed

IOV Satellite (Image: ESA)© 2011 NGI

GalileoInitial Operational Capability (IOC)

• Satellites (final design)

– Contract awarded for 14 satellites to new supplier – OHB

• IOV phase satellite from EADS Astrium

– Leads to constellation of 18 satellites in 2013/14

• 14 IOCs + 4 IOVs

• Enhanced ground segment (c.f. IOV)• Enhanced ground segment (c.f. IOV)

– More stations, more robust, more capabilities

– Ground Segment GMS contract awarded to Thales Alenia Space

– Ground Segment GCS contracts awared to EADS Astrium

• Increased, but incomplete services

– OS: Yes

– PRS: Partial

– SoL: TBA

– Commercial: Beta test

© 2011 NGI

GalileoFull Operational Capability

• Completion of Satellite constellation– Another 12 Satellites (incl. 3 spares; replacements TBA)

• Full ground infrastructure– Full functionality

– Full robustness and redundancy

• Full Services (probably)• Full Services (probably)

– Political debate continues• Could affect PRS and/or SoL Services

• Requires a further €1.9B– Proposed to come from established EC budgets

– ... but another Galileo political fight still likely!

• Schedule

– Start: soon!

– Completion: 2019/20

© 2011 NGI

Galileo ProgrammeDecision Making & Control

Political Decision Making

and Oversight

Management andExecution

European GNSSProgr Committee

MemberStates

EC

Fully Responsible forOverall ProgrammeManagement asEuropean GNSS

PoliticalProgramOversight

EUParliament

Budgetary Authority &Ultimate Decision-Making Bodies

for the GNSS Programmes (Galileo and EGNOS)

EUCouncil

ESA GSA

European GNSSProgramme Manager

ProcurementAgency

Technical Certification,Security Accreditation,

Market Preparation& Commercialisation

Independent ProjectMgt Expert Team

© 2011 NGI

Galileo FOC Procurement

ESASystem Prime & Procurement Agent

System Support

WP1

ECProgramme Management

DelegationAgreement

System Support

SpaceSegment

GroundControl

Segment

GroundMission

Segment

Launcher Operations

WP6WP5WP4WP3WP2

Time Services

GeodeticServices

SAR InitialServices

Site Hosting© 2011 NGI

Galileo FOC Procurement

Work Package Winner / Shortlisted

1. System Support ThalesAleniaSpace (Italy)

2. Ground Mission Segment ThalesAleniaSpace (France)

3. Ground Control Segment EADS Astrium (UK)

4. Space Segment

Work Order 1: OHB System (Germany)

Candidates for subsequent work orders:

• OHB System (Germany)

• EADS-Astrium Germany)

5. Launch Services Arianespace (France)

6. Operations OPAL (Germany+Italy)

© 2011 NGI

Estimated CostsBuild & Launch of Galileo

Item Cost in Euro

Phase 1 Definition (complete) €0.133 billion

Phase 2 Development and validation (under way) €1.502 billion

Phase 3 Deployment to IOC €3.405 billion

EGNOS costs to date included in Galileo Budged €0.520 billion

Funding for Galileo-related research Frameworkprogrammes FP5 – FP7

€0.48 billion

Estimated total build and launch costs €6.04 billion

Deployment of full FOC €1.9 billion

Operations Phase ( cost over 20 years – not commenced) €7.96 billion

TOTAL

Estimated build, launch, & running costs 25 years

€15.9 billion

© 2011 NGI

Galileo IOCCost Breakdown (M€)

Galileo IOCSatellites + launchers 1,600Ground System infrastructure 400Operations 275Systems Engineering 150Systems Engineering 150Procurement Agent management costs 195

EGNOS Exploitation & Ops (2008–13) 330

Support to the CommissionProject management & advisory services 27

Contingencies 428

Grand Total 3,405

Source: European Commission

© 2011 NGI

GPS / GalileoInteroperability

• Extensive EU/US negotiations at political and technicallevel over many years

• Signal interoperability:– (a) Interoperable Signals

• Future receivers using MBOC can track GPS & Galileo signals• Future receivers using MBOC can track GPS & Galileo signals

• Benefits of multiple GNSS constellations – greater signalavailability and coverage worldwide

• Higher accuracy in challenging environments

– (b) Non-Overlapping Compatible Signals

• (Military) desire to be able to remove one signal (X) withoutdisrupting another (Y)

• A point of contention since desire of the one military of one statemay not overlap with desire in another state!

© 2011 NGI

• Timescales– GPS & Galileo systems broadcast the difference between their

respective system times (GPST / GST) and Universal Time(UTC)

– Performance specified (maximum deviation, etc.)

– Can be solved in receiver by instigating “extra” unknown

GPS / GalileoInteroperability

– Can be solved in receiver by instigating “extra” unknown

– i.e. x, y, z, dT(GPS), dT(Galileo)

• Datums– GPS: WGS84, Galileo: GTRF, GLONASS: PZ90; etc.)

– Implement algorithmic correction in receiver to changecoordinates

© 2011 NGI

Summary

• Galileo Overview

• Services from Galileo

• Satellites & Orbits

• Ground Segments (Mission, Control)• Ground Segments (Mission, Control)

• Galileo Signals

• Status & Plans

• Institutional & financial aspects

© 2011 NGI

Contact Details

Professor Terry Moore

Director of the NGI

Nottingham Geospatial Building

The University of Nottingham

Triumph RoadTriumph Road

Nottingham

NG7 2TU

Telephone: +44 (0) 115 951 3886

Fax: +44 (0) 115 951 3881

Email: [email protected]

WWW: www.nottingham.ac.uk

© 2011 NGI

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