Bava_ Inrim
1 like683 views
The document outlines the importance of time metrology for satellite navigation systems, emphasizing the need for accurate and synchronized clocks in both ground and space environments. It describes various research activities at the Istituto Nazionale di Ricerca Metrologica (INRIM) related to atomic clocks, synchronization algorithms, and the development of time standards for applications in Galileo and GNSS. Additionally, it highlights collaborative efforts and specific projects aimed at enhancing the precision of timekeeping systems for satellite navigation.
Bava_ Inrim
- 1. October 15th, 2009 GALILEO / EGNOS & GNSS Galileo & GNSS: Research, developments and applications Time and Frequency Research at INRIM for Applications to Satellite Systems AUTHORS: Elio Bava, Istituto Nazionale di Ricerca Metrologica (INRIM) – Politecnico di Torino and Time & Frequency INRIM Group ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 2. 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. ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 3. THE METRE SI 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 light in vacuum during the time interval of 1 / 299 792 458 of a second ∆l = c ∆t By 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 ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 4. 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 ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 5. Main research activities in time metrology at INRIM clock mathematical atomic comparison and modelling clocks synchronization and algorithms techniques to realize and to contribute disseminate to the the Italian Standard Time International Atomic UTC(IT) Time (TAI) ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 6. Atomic clocks at INRIM Primary 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 ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 7. PRIMARY STANDARD: CRYOGENIC CS FOUNTAIN Ramsey signal 1 2 0.9 0.9 Transition Probability Transition Probability 0.6 0.6 0.3 0.3 0.0 -90 0 90 -4 -3 -2 -1 0 1 2 3 4 Center frequency /Hz Center frequency /Hz Accuracy No evidence of characterization unexpected biases at 10-16 level. at 1x10-15 level. ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 8. Rb STANDARD FOR SATELLITE APPLICATIONS Allan deviation measurement 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) ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 9. 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 ESA 2000 Nuovo sistema di sincronizzazione da e per Gavazzi Space Milano frequency distribution via satellite satelliti GalileoSat Time Interface Working Group ESA 2000-2001 From 1998 till the end 2009 Gruppo di lavoro Istituti Me trologia per Galileo ESA GALILEO Phase B2 ESA 2002 18 European collaborations Alenia Definizione architettura del sistema Galileo Industries 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 di Galileo Industries, Alenia Galileo Galileo Phase C0 ESA 2003-04 Progettazione sistema Galileo Industries, Alenia Galileo Time Service Provider (TSP) GJU 2004-2005 Definizione ruolo e requisiti Time Service FDC F NPL UK Provider 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 Galileo Phase CDE Ground Segment ESA 2005-2007 Sviluppo del Segmento di Terra Offerto da Alcatel F Giove Mission ESA 2008-2010 Caratterizzazione orologio a bordo di Giove Thales - I - Fr Advent ESA 2008-2009 Algoritmi per rilevazione anomalia orologio CMV Madrid ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 10. Galileo System Test Bed V1: 2002-2004 GPS Constellation GEO Two-way .. time transfer .. . . UTC(k) Experim. Sensor GPS OSS12 OSS12 Orbitography GSTB Experim. receiver Stations Processing Experim. receiver receiver receiver Processing Rubidium Centre UTC(k) Internet ftp transfer Rubidium Rubidium clocks clock clock Integrity clock Processing PTB and NPL Experimental Complementary Data Collection Precise Timing Station Sensor Stations IEN, Turin,Italy Formatting Networks Archive ... Monitoring & Cntrl Core Products Delivery Station1 Stationn ISTITUTO NAZIONALE DI RICERCA METROLOGICA
- 11. Galileo Precise Time Facility Development of the ground segment 2 Galileo Control Centers 2 Precise Time Facilities (PTF) Kayser Threde consortium Torino 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 Fidelity (2005-2009) UTC(k) labs • provide clock measurements • realise a composite time scale ISTITUTO NAZIONALE • ensure synchronisation to UTC DI RICERCA METROLOGICA
- 12. Current timing activity of INRIM H maser Rb clock GIOVE A GIOVE B INRIM is responsible of the characterisation of the on board clocks and provides the on ground reference clock (Active H Maser) connected to a GPS Galileo Sensor Station. In collaboration with ESA, Thales Alenia Space, ISTITUTO NAZIONALE GMV, Indra… DI RICERCA METROLOGICA
- 13. Timekeeping in 21st century : what to do • 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 ISTITUTO NAZIONALE DI RICERCA METROLOGICA