some cnes activities on optical telemetry and proposal for ccsds optical com bof j-l. issler october...
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Some CNES activities on optical telemetry
and
Proposal for CCSDS Optical Com BOF
J-L. Issler
October 2013
San Antonio
CNES Milestones for optical telemetry
■ Operationnal optical telemetry system ( LEO DTE ) Ka band DTE could not meet all data throughput future needs; In flight demonstration with an on-bord terminal in about 2020 All system validation tools will be available Validation of technologies (amplifiers, detectors, …) Validation of ground/board configurations close to an operational standardised case
■ Standardisation of optical communications completed in 2020 As needed by Optical Link Study Group (OLSG), IOAG, IOP 2020
■ Demonstration of some issues related to LEO DTE optical telemetry with a real link in 2015
■ Développement of on bord technologies (on-going for a few key technologies)
■ Technical studies of ques de transmission (on going)
■ Study and modeling of propagation channel (on going)
■ System studies (on going)
PILOT scientific software developed previously at ONERA/DOTA (“wave optics”);
From PILOT to TURANDOT (funded by CNES): interface suitable for both PLTM and Telecom simulations (Far Field Pattern on both the uplink and the downlink ) & automatic dimensioning & control engineering tool for turbulence simulation (main output: Far Field Patterns)
2 simulation modes: Snapshots: no time correlation long term statistical assessment Temporal: time correlation between 2 successive FFP
TURANDOT: Basics
Simulation of atmospheric turbulence on Earth-Space links:
The TURANDOT software
No turbulence (downlink)
TURANDOT simulations
input parameters: Simulation mode & random seed Uplink / downlink Number of output FFP (D < 1 s in temporal mode) DTx, DRx, waist & divergence + pixel size in the Rx plane
0.8µm < < 1.55 µm Vsat, Dsat, > 5° (validated for > 20°)
Hobs, Altobs
Wind speed, Cn2 profile or Cn
2 at reference altitude + Hufnagel Valley profile
Optional: Phase aberration (static), Pointing errors (temporal sequence)
Outputs: FFP
Auto-control
Air interface, PAT
Turbulence profile
Ref
ract
ion
ind
ex s
trcu
ture
par
amet
er C
n2 (
m-2
/3)
Distance in atmosphere (km)
TURANDOT: Validation
Validation with respect to reference cases: Analytical models when available: Rytov for downlink & weak turbulence in particular
Cross validation with experimental results: OICETS results published by NICT well reproduced by Turandot simulation for the 23.5° & 35.1° cases ONERA/NICT/CNES paper at ICSOS
conference TURANDOT validated for elevation angles > 20°
Further works
Atmospheric absorption & clouds/aerosol attenuation:
MATISSE software
Ground network optimization(w.r.t. to macroscopic availability):
optimization tool using cloudiness maps provided by Satmos
Ground based radiometric measurements for cloudiness & LWP mapping
Turbulence effects:On-going R&T activity to extend
TURANDOT down to 10° elevation angles + Cn
2 profiles measurements
CNES Optical telemetry demonstrator
MéO (OCA)
SOTA (NICT) on board SOCRATES (JAXA)
1.55 μmNRZ1Mbps or 10Mbps
1.06 μm
Goals for 2015 :Establish an LEO to ground optical link ( pointing, acquisition, tracking ) Measurements of the propagation environment effects of turbulances, Evaluation of telecom performances at low data rate to start with
NICT/CNES MOU
The mentioned advantages of 1550 nm are widely admited for LEO-ground direct links, since all the described on board equipments presently specifically designed for LEO to ground direct links only (DLR/BIROS/OSIRIS; NICT/SOCRATES/SOTA, ESA/Optel-mu, NASA/JPL on bord terminal, NASA/ on bord ISS …) should use 1550 nm downlink in the years to come (: for the LEO to ground specific high data rate telemetry link) for in orbit demonstrations.
For its experiment thanks to JAXA and NICT, CNES will use a 1550 nm LEO DTE downlink. The 1064 nm uplink is used do to the SOTA terminal design, but CNES will use 1550 nm uplinks for its future demonstration representative of an operational system.
A clear worldwide trend for specifically designed LEO DTE optical link experiments :
1550 nm downlinks
CNES proposals for optical TM links standards
Jean-Luc Issler, Géraldine Artaud
CNES proposals for CCSDS Optical Com BOF
- Standardization is required for global OGS-networks compatible with LEO-DTE, due to the need of interoperability specified by OLSG/IOAG/IOP
- We propose 3 blue book sets, in agreement with OLSG/IOAG/IOP needs• 1) One set for the High Photon flux
• 2) One set for the Low photon flux
• 3) A book for atmospheric data exchanges (including CON-OPS optimisations)
-Bleue book sets 1 and 2 are recommanded to be : One bleue book for frequency, modulation, beacons, PAT, … One bleue book for coding and interleaving
-LEO DTE scenario shall be considered at the same level and with the same global time line than other scenarii in all books
- This stay true in the case of a generic standard for links through atmosphere : such a generic standard would have to take into account the dynamics of LEO DTE links
10
11
-CCSDS should concentrate on physical layer (:layer 1), since existing protocol (layer 4, 3 & 2 ) are suitable, according to OLSG/IOAG/IOP. CNES fully support that
-OLSG identified a preliminary CON-OPS for optical links throught atmosphere : the site selection is made thanks to centralised meteorological data set. CNES think that the CON-OPS could be optimised in combining use of centralised meteo data and local “sky event” data ( aircraft and cloud data ).
-CNES support the idea of having reference atmospheric propagation model(s) for turbulances, scintillations, ... To allow true comparisons of different codings, interleavings, … standard proposals. Therefore, mutualisations of models and measurements seems to be needed for CCSDS
-CCSDS should consider with OLSG eye safety issues for its works on frequencies
Other CNES recommandations for Optical TM link standardisation
BACK UP SLIDES
For IOAG (OLSG,…)15 august 2012
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TélescopePointing
AcquisitionTracking
Injection In fiber
Amplificationfiltrage
Amplificationfiltering
ModulationCodingFraming
TelescopePointing
AcquisitionTracking
DemodulationDécodingDeframing
Amplificationfiltering
Pro
paga
tion
LEO terminalGround station
Beacon
collimation
REFERENCE ARCHITECTURE OF A LEO DTE OPTICAL TM LINK
NICT optical ground station (1.5-m optical telescope)
OICETS
*Morio Toyoshima, Hideki Takenaka et al. Frequency characteristics of atmospheric turbulence in space-to-ground laser links, Proc. SPIE 7685 (2010).
2 elevations Urban area line of sight:
unstable Cn² profile + HV (Cn²(ground) = 3,5 10-13 m-2/3
5 cm pupil area, APD detector
OICETS measurements
Coherence time : Measured ~ 500 µs vs TURANDOT ~ 600 µs
θ = 23,5°
Excellent agreement
Power Spectral Densities Normalized temporal covariance
Validation w.r.t. OICETS
θ = 35,1°
Coherence time: Measured ~ 400 µs vs TURANDOT ~ 380 µs
Excellent agreement
Power Spectral Densities Normalized temporal covariance
Validation w.r.t. OICETS
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IOAG Catalog-1 Return Data Delivery Service
18
Optical telemetry links beeing high data rate links, the level 2 CCSDS protocol (data link layer) to use is AOS (732.0). That is transfert frames of fixed length (for a given mission, the maximum length selectable is about 2000 bytes).
This protocol is adapted to high data rate links. That is not the case for TM space data link protocoal, which is adapted for medium and low data rate TM.
Therefore, the OAS protocol is recommanded by CNES for optical telemetry links, including Direct To Earth (DTE).
IOAG/OLSG/IOP doesn’t recommand redevelopment of a level 2 protocol for optical space telemetry. CNES fully support that
Identifications of IOAG catalog service wich can be reused for optical high data rate telemetry : Return Channel Frames Services : AOS for optical High Data Rate Telemetry
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IOAG Catalog-2 Data Delivery Service
20
Regarding level 3 protocols (network) and level 4 (transport), the DTN protocol suite in developpement at CCSDS is attractive for optical links since DTN, for instance, manage hand-over from one station to the other and automatic retransmissions of data not correctly received on the ground.
These two functionnalities will be very interestings for optical links, like the ones through the earth atmosphere and its clouds.
Therefore, the DTN protocol is recommanded by OLSG/IOAG/IOP to be considered and studied for optical links, including Direct To Earth (DTE), before any recommandation for a new development of a level 3 and 4 protocols. CNES fully support that
Identifications of IOAG catalog service wich can be reused for optical high data rate telemetry : Internetworking for DTN
850 nm 1064 nm 1550 nm
Antenna size
Data rate (including WDM consideration)
Availability of COTS
Atmospheric attenuation
Turbulence
Background light
Optics quality requirement
EYE SAFETY
TRL (*) (**) Year dependent
Year
dependent
Year
dependent
Good
Fair
Poor* TRL estimations agreed in the Optical Space Communication workshop are for Rb>1 Gbits/s in 2011 :For 850 nm : 5 ; for 1066 nm : 9; for 1550 nm : 6
** Which TRL in 2015 ? 2020 ? 2025 ? 2030 ? 2035 ? 2040 ? 2045 ? 2050 ? etc …
Conclusions of the Space Optical CommunicationWorkshop in Berlin the 17th of may 2011
This table was elaborated byall the participants*** to the 17
may 2011 workshop. Discussion occured for the criteria and the colors, and
the quasi-consensual obtained result as presented at the end of the workshop is
shown here.
*** DLR, JAXA, ESA, NASA, CNES, MIT-Lincoln Lab, DIN, HHI-Fraunhofer, RUAG-Space, TU Gratz, Tesat, Carl Zeiss Optronics, …
22
- Some military plane & helicopter pilots, parachutists, pedestrians, … have nigh vision magnifying helmets (see slide 4). This as to be considered (for instance) for operations close to the uplink of OGSs
- Some aerial crafts are not moving quickly : helicopters, ballons, … : important for spacecrafts not « moving quickly » like GEOs
- the future GEO-telecom powerfull optical links shall be considered by civil aviation (+helicopters+ballons+ … ) authorities for eventual update of eye safety computation methods ( same remarq for space agencies managing astronauts ). We have to ensure that the EYE SAFETY methodology updates proposed to the concerned authorities are compatible with commercial and non commercial space laser transmissions.
- some animals have night vision ( NB : CNES already received an « ecological » question related to space laser transmissions )
- atmospheric scintillations should be considered in EYE SAFETY worst case computations related to space earth optical transmissions
- For the long-term, a wide diversity of astronaut altitudes have to be considered (LEO, moon-transfert*, moon orbit*, moon surface*, asteroid transfert, GEO ?(an Apollo mission option was in GEO), HEO ? ** ). Proximity operations or rendez vous with a laser transmiting spacecraft has to be considered
- Astronauts have a helmet provided with a sliding sun mask : EYE sefety shall be considered with and without using the sun mask.
* : 2025 ? ** Nota Bene : some space agencies road maps forsee quasi generalised usage of optical links for HDRTM in 2040. The 2040 situation has therefore to be choosen to consider worsk cases for EYE SAFETY studies.
SOME EYE SAFETY CONSIDERATIONS
« The Zoom Binocular with Recommended by Captains and Astronauts 20-144x70mm ».
Leica Trinovid 8x42 and Trinovid 10x42 Binoculars Unigadget sellings
« NASA sent a Trinovid binocular with astronauts on a lunar exploration mission on Apollo 11 in 1969 »
« Meopta’s binoculars and spotting scopes are used by astronauts »
Meopta Meostar 12x50 WP
x12.>x20
Exemples of binoculars used by astronauts,minoring assumptions to be considered
for EYE SAFETY studies
Exemples of IR magnifing night vision devices( some are helmet mountable )
Manufacturer : Excelis