OGS-OFL

Competitiveness & Growth

Status

Ongoing
Status date

2022-11-16
Activity Code

6A.060

Objectives

The main objectives of the OGS-OFL activity are

• to define a preferred concept of the optical feeder link system that matches the features and needs of optical payloads in GEO HTS
• to identify critical optical technologies that require de-risking
• to perform selected risk mitigation activities on the constituents of such system with emphasis on the optical ground station and its S/W

The simulation tool provides the following features:

Use of published models of atmospheric turbulence strength
Supports Downlink calculation: temporal behavior & statistics of irradiance
- at the OGS entrance pupil
- and in the OGS focal plane / single-mode receiver
Supports Uplink calculation: temporal behavior & statistics of irradiance
- at the target satellite
- taking into account adaptive pre-compensation & anisoplanatism (point-ahead)
Allows for sizing of the downlink / uplink aperture
- Dimensioning of the bi-directional AO system
Includes effects of wind speed

OGS-OFL objectives

The Lab Demonstrator provides the following key features:

Simulates atmospheric turbulence, using rotating phase screens
Validates simulation tool w.r.t. beam propagation effects
- at the target satellite, taking into account adaptive pre-compensation & anisoplanatism (point-ahead)
- at the ground receiver
Can be used as a "plug-in" atmospheric channel simulator
- investigate & demonstrate end-to-end performance of an optical communications system including atmospheric channel impact

transparent to communications system (Tx/Rx fiber interfaces)

Challenges

This project complements findings of various optical feederlink investigations, such as ESA projects ORELIA and ONUBLA, as well as the BATS project under EU FP7. The challenge is to establish a preferred concept for an optical feeder link system of 1Tbis/s and more:

Constitute customer requirements and carry out system analysis
Trade-off optical modulation / demodulation schemes, incl. multiplexing / de-multiplexing, optical amplification, and atmospheric turbulence mitigation
The high-power handling capability of a large actuator deformable mirror is investigated
The activity scope considers an optical bi-directional point-to-point Space-Ground-Links to GEO, while staying compatible to Tbit/s OFL performance requirements

In addition, high-power handling capability of a large actuator deformable mirror is investigated.

Benefits

The purpose of the proposed activity is to support the development of the Adaptive Optical Ground Station (AOGS) product series of Synopta, both, stationary or transportable, towards application in Optical Feeder Links (OFL). This type of optical ground station is capable of handling multi-100Gbit/s data rates.

Features

The Synopta AOGS product series support high-data-rate laser communication links for

Data relay uplink/downlink with GEO satellites
High data rate feeder links for GEO satellites
Direct-to-Earth links, LEO and GEO

In general, the AOGS is fully transparent to the type of modulation applied. In particular, so-called transparent optical modulation schemes and their corresponding appropriate RF-optical (de-) modulation technologies for Tbit/s feeder links and corresponding high transmit power levels are supported by the Synopta AOGS.

The main features of the Synopta AOGS product series are

Dual wavelength capability (1'064 nm, 1'550 nm)
Support of bi-directional communication and high-data rate up- and down-links
Enables Terabit/s optical feeder links (high-power AO system)
Full interoperability with various types of user specific communication systems (coherent or direct detection)
Standardized control and communication interfaces
High operational autonomy with minimum infrastructure requirements
Networking capability to support route diversity concepts

The OGS S/W provides the following features:

Semi-automatic system definition
Flexibility w.r.t hardware and platforms
Acquisition / tracking sensor support Automatic link execution (PAT state machine)

System Architecture

The functional test system to be developed in this project is an End-to-End OFL Lab Demonstrator, comprising

Optical transmitter and receiver
RF modems for validation of user signals
Adaptive Optics
Atmospheric Channel Simulator
OGS S/W

Plan

The work plan is extended to seven milestones (PDR, TRR, ATR, TRR2, CCN01-FR, CCN02-MTR, CCN02-FR) which separate an analytical baseline work from a functional test campaign.

The baseline work (first three parts) concludes with the Acceptance Test Review.

The risk mitigation activities consist of the following four reviews.

Requirements and System Analysis (KO to PDR)
B/B Manufacturing & Test Preparations (PDR to TRR)
Lab Demonstrators, Test Campaign, Appraisal (TRR to ATR)
Risk mitigation before feasibility demonstration (ATR to FR)
Risk mitigation activity covers OGS S/W (CCN2-KO to CCN02-FR)

Current status

The project “Optical Ground Station for Tbit Feeder Links – OGS-OFL” is completed in November 2022.

The main achievements are:

Elaboration of an OFL system concept based on the coherent transmission of analogue waveforms, using optical image rejection transmitters, and optical image rejection receivers.
Mitigation of technical risks concerning the performance of the novel transmission scheme on the optical channel, the performance of adaptive uplink beam shaping in view of optical turbulence, and the power handling capabilities of key optical components in the ground segment.
Development of dedicated S/W improving configurability and maintainability of the final OGS-OFL product. Within this scope, the wavefront sensor processing, system calibration, real-time performance, and closed-loop tip/tilt rejection have been tested.

The OGS-OFL project is followed-up by further development in the context of ARTES Partner programme AIDAN and ARTES ScyLight activity CREOLA.