Time Facility for German Galileo Test Environment GATE · Sulzberg. Folie 8 > Vortrag > Autor Dokumentname > 23.11.2004 J. Furthner, Institute of Communications and Navigation,

Folie 1, GTFS 2005 > JF

Time Facility for German Galileo Test Environment GATEJ. Furthner, German Aerospace Center (DLR)

Folie 2 > Vortrag > AutorDokumentname > 23.11.2004

J. Furthner, Institute of Communications and Navigation, DLRGTFS 2005, 05.12.2005, Herrsching, Germany <2>

Content

Overview of GATEMajor Objectives of GATEGATE Field and Service AreaFunctions and Elements of GATE Control SegmentFunctional Architecture of GATE Time FacilityRequirements for GATE Time FacilityPhysical Architecture of GATE Time FacilityControlling of GATE Time FacilityMan Machine Interface and Location of GATE Time Facility



Overview of German Galileo Test Environment GATE

What is GATE?Ranging system using Galileo signalsBased an stationary terrestrial signal transmittersOpen to any user

Where is the GATE service area?Near to Munich (Berchtesgaden)

Who is the customer?German Aerospace Center DLR

Status of GATE?Starting for operation in 3rd quarter 2006

Who develops GATE?A consortium of 9 companies/universities IfEN GmbH (Poing) being the prime contractor



GATE – Consortium



Major Objectives of GATE

Signal ExperimentGain experience in building a Galileo ranging systemGain experience with new Galileo signal structure: flexible (BOC(1,1); extendible (GPS-L2C, L5); adaptable (Interference, Jamming)

Receiver TestingTest facility for Galileo receiversTesting of new BOC receiver algorithms

with realistic signal behaviour and strength, atmospheric effectsUser Application

Provide an environment for test of user applicationsEspecially for hybrid GPS/Galileo applicationsExtendible for local applications (CAT I-III) beyond FOC



GATE – Limitations & Capabilities

GATE vs. „the Real Thing“Constraints in geometry (DOP / Visibility)

Careful choice of service areaConstraints in local signal propagation effects

Multipath: GTS-GMS geometry corresponds to SV-GMS worst case, but multipath due to user motion dominating effect!

Geometry induced effects can be emulatedIonosphereTroposhere

GATE vs. Laboratory / SimulatorEnd to end test of receiver, including antennaReal time dynamics, instead of predefined trajectoriesUser selectable hosting vehicle applicable for application



GATE Field Segment in Berchtesgaden

Location of Transmitter Stations:GrünsteinToter MannStörhausKneifelspitzeKehlsteinhausJenner

Location of Monitor Stations:Sulzberg



GATE Service Area in Berchtesgaden

Size: > 25 km²Performance Criteria:

Min. 4 visible GTSHDOP < 2VDOP 6-20

Infrastructure Criteria:Availability of GMS platformsMountain area for GMS elevation

Typical User Environment Available:

StreetsRailways

Visibility



Functions of the GATE Control Segment

Hosting and providing the GATE system timeMonitoring and controlling of the entire GATE systemArchiving off all necessary data (housekeeping as well as user relevant data)Hosting and operating a control centre which serves as operational node of GATE including e.g. mission planningProvide an appropriate interface to the GATE user community

The main elements of the GCS are the GATE Time Facility (GTF)GATE Monitoring & Control Facility (GMCF)GATE Archiving and Data Server (GADS)GATE Data Transfer Network (GDTN)GATE Mission Support Facility for Standard user (GMSF-S)



The Elements of the GATE Control Segment GCS

ControlSegment

Mission Segment

GPF

GTS

GPSsatellites

Galileo IOV satellitesGPS /

Galileo

GUT

GMS TransmitSegment

GNSSsensor

GTF GCC

GMCF

GADS

Operators

UTC(DLR) Lab

Monitoring system

Expertteam

Master clockwith hot-spare

NTPserver

GMSF-S



The Elements of the GATE Control Segment GCS

ControlSegment

Mission Segment

TransmitSegment

UserSegment

GTF GCC

GMCF

GADS

Operators

UTC Lab

Monitoring system

Expertteam

GPF

GTS

GPSsatellites

Galileo IOV satellites

Master clockwith hot-spare

GUT

NTPserver

GMS

GMSF-S

GNSSsensor

GURx

GPS / Galileo



The Elements of the GATE Control Segment GCSGATE Control Segment

GMCF

GATE Monitoring & Control Facility

GADS

GATE Archiving & Data Server

GTF

GATE Time

Facility

GMSF-S

GATE Mission Support Facility

Standard

Located at DLR GSOC Control Centre

Located at DLR TL



Functional Architecture of GATE Time Facility GTF

The functions of GTF aregeneration of reference time scale of GATE: GATE System Time GASTprovision of access to GAST for other GATE elementsprovision of access to UTCprovision of access to GPS Time

GTF takes the time keeping function similar to the Precise Time Facility in Galileo.Decreasing the project costs, the GTF is hosted by the DLR Time Laboratory (DLR-TL) The GTF has access to clocks and products (time scales) which are provided by the DLR-TL



GTF – Functional Architecture

The receivers are configured to send the following messages to the GPF:GPS observationsGPS navigation messages

referenced to GASTAdditional Parameters through an internal OS service to GPF

GAST-UTC offset and rate UTC-TAI offsetGATE MC-UTC(DLR) offset and rate

Copies of all to GPF transmitted data to GMCFReceiving and transmitting configuration data for the GTF from and to GMCFSynchronisation of all GATE elements via NTP protocol



GTF – Functional Architecture

DLR Time Lab

Steeringto UTC

Responsibility of DLR Time Lab

Generation ofUTC(DLR)

Interfaceto BIPM

Responsibility of GTF

Elementcontrol &

interfacing

Networksynchronzation

Interface toGPS Time andGAST provision

GPF/GMCF

NTP synch

M&C data/GPS obs

M&Cdata

GAST

BIPM

UTC(DLR) correction

GAST correction

UTC(DLR)

GAST

UTC-UTC(DLR)

GPS SIS

Generation ofGAST

GAST-UTCcomparison

GATE-specificoperations

UTC correction



GTF – Requirements

GAST shall be produced at the GTF from a high-performance clock being the GATE master clock.The GTF shall have access to UTC.The offset between GAST and UTC < 100 ns modulo 1s over any 1-year time interval within a 95% confidence level.The offset between TAI and GAST < 50 ns (96%), assuming the estimation of TAI six weeks in advance.The frequency instability of GAST expressed in terms of Allan-Deviation relative to TAI shall be better than 1e-13 over 10 000 s.The frequency instability of GAST expressed in terms of Allan Deviation relative to TAI shall be better than 2e-14 over 1 month.The life time of the GATE master clock shall be at least 3 years. The MTBF of the GATE master clock shall be no more than 1 failure per 12 500 hours.The availability of the GTF has to be at least 98.1 percent in order to meet the overall GCS availability requirement.



GTF – Physical Architecture

Detailed Availability of GTF and its elements without redundancy

Availability of GTF reaches not the requirement (98.1% ) without redundancy




Total GAST availability without redundancy

Total GAST availabilitywith redundancy




High availability of GTF needs a redundancy of single GTF elements The physical architecture of the GTF is based on COTS hardware. It consists of

2 Dell Windows Server 2003 (XEON 3 GHz, 1 GB RAM, RAID1 36 GB SCSI, 10/100/1000 Mbit Ethernet)2 GPS time receiver Septentrio PolaRx2.Meinberg NTP/LAN Server with GPS and 1PPS signal input

GTF will have access to DLR campus LAN to enable data exchange with other GATE elements.The CPU clocks of the servers will be synchronized to GAST through the NTP protocol using the campus LAN.




DLR Time Lab

GPS receptionsub-system

Equipment of DLR Time Lab

GPS RX 1 PC1

GTF

NTP server

UTC(DLR)/GASTgenerationsub-system

UPS

WANI/F 1

Power supply 1 PPS 10 MHz Data GPS signals

Networkinterface

GPS RX 2BIPM/IERS Interfacesub-system

WANI/F 2

GPF/GMCF

GPF/GMCF

PC2




Clock subsystem

Phase microstepper

Switch

Measuring subsystem

Phase microstepper

GAST realisation subsystem

GPS Rx GPS Rx

To GATE Control Center

Control PC Control PC

GAST processing

GPS Rx

Control PC

UTC(DLR)

To GATE Control Center

Control CenterInterface



PTF – Physical Architecture

Clock subsystem Measurement subsystem

GST processing

Precise Timing Facility

Time Service Provider

GST-to-TAI correction

GST realization subsystem

GPSconstellation

Galileoconstellation

GSTGPSSIS IF

Galileosensor station

GPS/Galileotime offsetprocessing



Controlling of GTF via GMCF









GTF – Man Machine Interface at the GMCF



The GTF at DLR Time Laboratory

UTC(DLR) Time Laboratory

GTF



Thank you for your attention

Documents

Time Facility for German Galileo Test Environment GATE · Sulzberg. Folie 8 > Vortrag > Autor Dokumentname > 23.11.2004 J. Furthner, Institute of Communications and Navigation,