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

12

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

17

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

19

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 ».

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« 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 )

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