Géoazur - FIRST-TF

Géoazur

Modification request

https://geoazur.oca.eu/en/home-geoazur Category: Research or metrology institute

Activities Time-Frequency:

Workforce: 7with: 5 permanents, 2 non-permanent

VALBONNE, France

Data analysis:
Time transfer by free space laser: from ground-to-space
Time transfer between remote ground clocks in Geodetic observatories
Monitoring of space oscillators/clocks for the navigation : OUS DORIS on Jason satellites & Oscillator of LRO (Lunar Orbiter, NASA)
Webservice T2L2 at OCA: http://www.geoazur.fr/t2l2/en/data/v4/
Monitoring of the local time scale at Grasse-geodetic-Observatory (Calern) with GNSS

Research & Development (technological):
Event timer
Time and frequency signal generator
Laser ranging
Time Transfer by laser link
Free space optical telecom

Campaign(s):
Time Transfer in Europe and Asia
Ground calibration: GNSS, laser ranging, Time Transfer
Optical telecom

Contribution to:
Instrument spatial : Time Transfer by Laser Link, T2L2
Réseau géodésique laser : International Laser Ranging Service, ILRS
Programme INSU/CSAA : GRAM
Projet Télécom optique : DOMINO

International collaborations:
NASA-Goddard Space Flight Center, Greenbelt, Maryland, US

Crédit photo : Cyril FRESILLON / GEOAZUR / FIRST-TF / CNRS Photothèque.

Expertise :

Oscillators
- RF and microwave oscillators and synthesis
  - Piezoelectric technologies
  - Disciplined oscillators• Electronic design of VCXO frequency synthesis
    User of rubidium Rb oscillator slaved on GPS
- Optical oscillators, lasers
  - Laser sources• User of laser diode @ 1550 nm (telecom)
    Design of Nd:Yag Neodymium Yag flash pumped. picosecond. Energy 500 mJ. Mode locked : Acousto, Dye, Semi conductorUser of diode pumped picosecond laser : laser cavity slaved on 100 MHz frequency reference
Atomic references
- Micro-wave clocks and subsystems
  - Thermal beam clocks• User of frequency standard HP5071A (2 clocks on the OCA-Calern site)
  - Masers• User of a commercial H-Maser (T4 Science). time and frequency reference of the TF OCA laboratory
Synchronisation, frequency transfer and time scales
- Micro-wave links
  - GNSS• Comparing analysis of ground-to-ground time transfers by T2L2-laser and GNSS-PGS (iPPP solutions)
    User of GPS TF system (GTR50)
  - Two way systems• User of a TWSTFT based on a Satre Modem. Remote control of the OCA H-Maser trough the TWSTFT
  - Wired links• Design of time and frequency controlled ditributor (sub-picosecond)
- Optical links in free space
  - Pulsed optical links in free space• Time transfer by Laser T2L2. 9 years of space mission since 2008. experiments at ground level, data analysis, and applications in space geodesy/navigation and fundamental physics)
    Cooperation with the Technical Univ. Munich on time transfer by laser ranging, with the ELT package onboard the ISS (ACES)
  - Continuous optical links in free space• Free Space Optical telecom (ground and satellite)
    Atmospheric turbulence effects on free space Optics
- Time scales• Monitoring by the T-Way technique of the local time scale at the geodetic observatory Grasse (Calern), using calibrated GNSS link.
  Instrumentale locale scale
  Current (2017-2018) experiment at European level of the construction of a time scale based on h-masers in geodetic observatories and time transfer by laser links T2L2
Specific methods of time-frequency metrology
- Noise
  - Phase noise, PLL• Design of event timers to measure noises
  - Short term stability, long term stability• Charaterization of space oscillators, monitored by time transfer by laser link (laser ranging on T2L2/Jason2 and LRO-moon), on the short term (1-1000 seconds) as well as on the long term (over months and years).
- Systematics, Accuracy, Calibration
  - Systematics in time transfer methods• Determination of systematic errors and bias with the time transfer by laser ranging technique used in geodetic observatories (Grasse, England, China).
- Chronometry
Techniques for time-frequency metrology and applications
- Electronics
  - Analog electronics• Low noise linear amplification
    PLL
  - Digital electronics• High speed digital electronic (DC-25 GHz)
    FPGA
- Optics
  - Guided optics, specific optical fibres• User of gradient fiber with large étendu de faisceau (coupling through the atmosphere)
  - High sensitivity, low noise photodetectors• Electronic design of Geiger photodiode (Si Silicon or InGaAs Indium gallium arsenide)
    Electronic design of low noise avalanche photodiode
  - Control of the optical beam characteristics• User of high speed optical modulator (DC-25 GHz)
- Sensors
  - Pressure sensors

Connected Sectors:

Fundamental science
- Fundamental metrology• Comparison of accuracy and stabilities, of ground-to-ground time transfer links between the microwave GPS (different solutions) and the laser-T2L2 techniques.
- Tests of fundamental physics• Test(s) of the gravitational frequency shift at space and ground level, and 1-way test of the isotropy of the speed of light using the laser rangin technique and time transfer.
Positioning and navigation
- Satellite positioning, GNSS• Applications of the time transfer by laser link technique for the satellite navigation with the onboard software DIODE on Jason-2 (T2L2)
- Tracking probes in the Solar system• Applications of the time transfer by laser ranging technique for the satellite navigation of LRO spacecraft around the Moon (1-way laser ranging).
  Proposal of time transfer projects in the solar system
Network synchronisation
- Telecommunications• Free space optical telecom. demonstration of data transfer from space to ground : NICT (japan). NASA (USA). DLR (Germany)
Environment and health
- Geoscience (geodesy, geophysics)• Applications of the time transfer by laser link technique, T2L2 and 1-way ranging, to the synchronization of the international laser ranging network (of 35 laser stations) and to the monitoring of the DORIS space oscillator on Jason-2. studies of the improvement of the geocentric positioning from these technqiues and consequences for the ITRF solution.

FIRST-TF Network

FIRST-TF Contact(s):