bava_ inrim

ISTITUTONAZIONALEDI RICERCAMETROLOGICA

AUTHORS:AUTHORS:Elio Bava,Elio Bava,

Istituto Nazionale di Ricerca Metrologica (INRIM) Istituto Nazionale di Ricerca Metrologica (INRIM) –– Politecnico di TorinoPolitecnico di Torino

and Time & Frequency INRIM Groupand Time & Frequency INRIM Group

October 15th, 2009October 15th, 2009

GALILEO / EGNOS & GNSSGALILEO / EGNOS & GNSS

Galileo & GNSS: Research, developments and applicationsGalileo & GNSS: Research, developments and applications

Time and Frequency Research at INRIMfor Applications to Satellite Systems


TIME METROLOGY AND NAVIGATION SYSTEMS

Time Metrology is fundamental for NAVIGATION and POSITIONING

GNSS use clocks (frequency standards + counters) and carry out measurements of propagation time of EM signals from a source to a receiver for a distance estimate.

E.g.: in spherical navigation position is estimated by measuring distances from 3 points having a known position.


THE METRETHE METRESI unit of time (13th CGPM 1967):

the second is the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground

state of the caesium 133 atom.

SI unit of length (17th CGPM 1983) took into account also the needs linked to the navigation systems:

the metre is the length of the path travelled by lightin vacuum during the time interval of 1 / 299 792 458 of a second

∆l = c ∆tBy definition c = 299 792 458 m/s

Biases due to electromagnetic properties of the medium and to gravitation are to be known and taken into account


Length measurement depends on time measurement

therefore we need clocks (on Ground and in Space)

stable, accurate, space qualified, reliable,small, light, low consuming

Clocks in Space, Control and User segments,altough with different stability characteristics,

must be syncronized to the highest level of accuracy.

Link to the Universal Time Coordinated (BIPM, Paris) mandatory


Main research activitiesin time metrology at INRIM

atomicclocks

clockcomparison andsynchronization

techniques

mathematicalmodelling

and algorithms

to realize anddisseminate

the Italian Standard TimeUTC(IT)

to contributeto the

International Atomic Time (TAI)


Atomic clocks at INRIMAtomic clocks at INRIMPrimary Cs standard (fountain, room temperature, working)

Primary Cs standard (fountain, liquid nitrogen, preliminar operation)

Cs beam, Rb cell and H maser standards to maintain UTC(IT)

Rb cell frequency standards for space applications

- Maser (Coherent Population Trapping), 2000 – 2003, ESA- Pulsed Optically Pumped (μwave detection), 2003-2006, ASI- Pulsed Optically Pumped (optical detection), 2008-2009, ESA


-90 0 900.0

0.3

0.6

0.9

Tran

sitio

n Pr

obab

ility

Center frequency /Hz

PRIMARY STANDARD: CRYOGENIC CS FOUNTAINPRIMARY STANDARD: CRYOGENIC CS FOUNTAIN

-4 -3 -2 -1 0 1 2 3 4

0.3

0.6

0.9

Tran

sitio

n Pr

obab

ility

Center frequency /Hz

No evidence of unexpected biases

at 1x10-15 level.

Ramsey signal1 2

Accuracy characterization

at 10-16 level.


POP maser (ASI contract) : σy(τ) ≈ 1.2 × 10−12 τ - 1 / 2, 1 ≤ τ ≤ 50000 s.POP with optical detection in progress (ESA contract) :

fundamental limit ⇒ σy(τ) ≈1×10−13 τ - 1 / 2

CAUTION:laser and microwave noises may overcome this limit (3-6×10−13 τ - 1 / 2)

Allan deviation measurementAllan deviation measurement

Rb STANDARD FOR SATELLITE APPLICATIONSRb STANDARD FOR SATELLITE APPLICATIONS


Progetto Ente Anni Scopo CapoCommessa

Autonomous Ephemerids Determination ESA 1998 Possibi le architettura GNSS 2 DLR D

Comparative System Study ESA 1999 Confronto diversi sistemi GNSS ALENIA Spazio

GEMINUS CE 2000 Definizione dei servizi RACAL UK

GALA CE 2000 Valutazione Sistema Galileo ALCATEL F

GALILEOSAT ESA 2000 Architettura del sistema ALENIA Spazio

New methods and systems for time and frequency distribution via satellite

ESA 2000 Nuovo sistema di sincronizzazione da e per satelliti

Gavazzi Space Milano

GalileoSat Time Interface Working Group ESA 2000-2001 Gruppo di lavoro Istituti Me trologia per Galileo ESA

GALILEO Phase B2 ESA 2002 Definizione architettura del sistema Galileo Industries Alenia

GALILEO Phase B2 Consolidation 2002 ESA 2002 Definizione architettura del sistema Galileo Industries, Alenia

Galileo System Test Bed V1 ESA 2002-2005 Prove sperimentali a Terra degli algoritmi diGalileo

Galileo Industries, Alenia

Galileo Phase C0 ESA 2003-04 Progettazione sistema Galileo Industries, Alenia

Galileo Time Service Provider (TSP) GJU 2004-2005 Definizione ruolo e requisiti Time ServiceProvider

FDC F NPL UK

Galileo System Test Bed V2 ESA 2005-2007 Prove tecniche con 2 satelliti ed orologi Galileo Galileo Industries

Galileo Time Service Provider (TSP) GJU 2005-2008 Progettare e realizzare prototipo TSP Helios UK

Precise Timing Facility (PTF) ESA 2005-2008 Sviluppo, installazione e prova PTF Consorzio Torino Time

PROGENY GJU 2005-2007 Esperti a sostegno della GJU FDC F

Galileo Phase CDE1 System Verification ESA 2005-2007 Sviluppo del sistema fino alla IOV Offerto da GAIN, Alenia

ESA 2005-2007 Sviluppo del Segmento di Terra Offerto da Alcatel F

From 1998 till the end 200918 European collaborations

Advent ESA 2008-2009 Algoritmi per rilevazione anomalia orologio CMV Madrid

Galileo Phase CDE Ground Segment

Giove Mission ESA 2008-2010 Caratterizzazione orologio a bordo di Giove Thales - I - Fr


OSS12

Rubidium clock

Experim.receiver

OSS12

Rubidium clock

Experim.receiver

UTC(k)

UTC(k) clocks

Experim.receiver

GPSConstellation GEO

Orbitography Processing

GSTBProcessingCentre

ExperimentalPrecise Timing Station

IEN, Turin,Italy Data CollectionFormattingArchiveMonitoring & Cntrl

SensorStations

Rubidium clock

GPSreceiver

Internet ftp transfer

Integrity Processing

Two-waytime transfer

ComplementarySensor StationsNetworks

Core Products DeliveryStation1 Stationn...

...

...

Galileo System Test Bed V1: 2002-2004

PTB and NPL


Development of the ground segment 2 Galileo Control Centers2 Precise Time Facilities (PTF)Kayser Threde consortiumTorino Time Consortium (CTT)with INRIM, Torino Wireless, Finpiemonte,Politecnico di Torino,SEPA, SIA, Alenia Spazio,Istituto Superiore Mario Boella (ISMB)INRIM is developing the time scale algorithm supporting calibrations

UTC(k) labs • provide clock measurements

• realise a composite time scale• ensure synchronisation to UTC

Galileo Precise Time FacilityGalileo Precise Time Facility

Fidelity (2005Fidelity (2005--2009)2009)


Current timing activity of INRIM

Rb clockH maser

GIOVE AGIOVE A GIOVE BGIOVE B

INRIM is responsible of the characterisation of the on board clocks and provides the on groundreference clock (Active H Maser) connected to a GPS Galileo Sensor Station.

In collaboration with ESA,Thales Alenia Space,

GMV, Indra…


• Clocks and (optical) frequency standards

• Remote clock comparison systems:GNSS receivers, calibration issues and noise reduction multisystem solution (GPS + GALILEO + GLONASS)

• Algorithms: clock monitoring for integrity

• Time Scale realisation: robustness is the issue

Timekeeping in 21st century : what to doTimekeeping in 21st century : what to do


THANKS!

bava_ inrim

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